From 26139c4ae2aa3d7304c9daf7a002344b28c94427 Mon Sep 17 00:00:00 2001
From: David Capello <david@igarastudio.com>
Date: Fri, 29 Mar 2019 15:57:10 -0300
Subject: [PATCH] Add tilemap layers (#977)

This is the first commit with a simple tilemap editor. Still buggy but
functional in several ways. Several changes were made:

* NewLayer command can receive a tilemap=true to create a new tilemap
  layer
* New ToggleTilesMode command added to switch between the palette and
  the tileset in the ColorBar (the ColorBar was expanded to show
  colors or tilesets with a generic AbstractPaletteViewAdapter)
* All commands to create new layers were moved to Layer >
  New... submenu
* There are a new tileset chunk to save tilesets in .aseprite files,
  and a new kind of cels to save tilemaps
* Added doc::LayerTilemap, doc::Tileset, etc. and several other types
  to handle tilesets/tilemaps in the doc layer.
* Added doc::Grid class with grid specifications that indicates how a
  tilemap <-> tileset must be drawn
* Added and expanded cel operations to work with tilemaps and
  conversions between regular LayerImage cels <-> LayerTilemap cels
  (e.g. copy cels in the timeline between layer types)
---
 data/gui.xml                               |   4 +
 data/pref.xml                              |   1 +
 data/strings/en.ini                        |   3 +
 docs/ase-file-specs.md                     |  67 ++-
 src/app/CMakeLists.txt                     |  11 +-
 src/app/cmd/add_tile.cpp                   |  92 ++++
 src/app/cmd/add_tile.h                     |  56 +++
 src/app/cmd/add_tileset.cpp                |  88 ++++
 src/app/cmd/add_tileset.h                  |  53 ++
 src/app/cmd/copy_cel.cpp                   |  12 +-
 src/app/cmd/copy_cel.h                     |   9 +-
 src/app/cmd/crop_cel.cpp                   |   8 +-
 src/app/cmd/crop_cel.h                     |   1 +
 src/app/cmd/flatten_layers.cpp             |   2 +-
 src/app/cmd/move_cel.cpp                   |   4 +-
 src/app/cmd/remove_tile.cpp                |  42 ++
 src/app/cmd/remove_tile.h                  |  30 ++
 src/app/cmd/remove_tileset.cpp             |  43 ++
 src/app/cmd/remove_tileset.h               |  31 ++
 src/app/cmd/set_cel_data.cpp               |   5 +-
 src/app/cmd/shift_masked_cel.cpp           |   2 +-
 src/app/cmd/trim_cel.cpp                   |   4 +-
 src/app/cmd/unlink_cel.cpp                 |   3 +-
 src/app/cmd/with_tileset.cpp               |  31 ++
 src/app/cmd/with_tileset.h                 |  32 ++
 src/app/cmd_sequence.h                     |   8 +-
 src/app/commands/cmd_clear_cel.cpp         |   7 +-
 src/app/commands/cmd_fill_and_stroke.cpp   |   1 +
 src/app/commands/cmd_mask_content.cpp      |   4 +-
 src/app/commands/cmd_new_layer.cpp         |  24 +-
 src/app/commands/cmd_toggle_tiles_mode.cpp |  42 ++
 src/app/commands/commands_list.h           |   1 +
 src/app/doc.cpp                            |  12 +-
 src/app/doc.h                              |   2 +
 src/app/doc_api.cpp                        |  13 +-
 src/app/doc_api.h                          |   2 +-
 src/app/doc_event.h                        |   5 +
 src/app/doc_exporter.cpp                   |   6 +-
 src/app/doc_observer.h                     |   3 +
 src/app/file/ase_format.cpp                | 164 +++++--
 src/app/file/file.cpp                      |   3 +-
 src/app/file/gif_format.cpp                |   2 +-
 src/app/script/app_object.cpp              |   7 +
 src/app/script/engine.cpp                  |  16 +
 src/app/script/engine.h                    |   5 +
 src/app/script/grid_class.cpp              |  94 ++++
 src/app/script/image_class.cpp             |  12 +-
 src/app/script/layer_class.cpp             |  20 +
 src/app/script/pixel_color_object.cpp      |  24 +
 src/app/script/sprite_class.cpp            |   8 +
 src/app/script/tileset_class.cpp           | 104 ++++
 src/app/script/tilesets_class.cpp          |  62 +++
 src/app/site.cpp                           |  12 +
 src/app/site.h                             |   8 +-
 src/app/tileset_mode.h                     |  24 +
 src/app/transaction.h                      |   4 +-
 src/app/tx.h                               |   4 +
 src/app/ui/color_bar.cpp                   | 230 ++++++++-
 src/app/ui/color_bar.h                     |  25 +-
 src/app/ui/doc_view.cpp                    |   6 +
 src/app/ui/doc_view.h                      |   2 +
 src/app/ui/editor/drawing_state.cpp        |  10 +
 src/app/ui/editor/drawing_state.h          |   2 +
 src/app/ui/editor/editor.cpp               |  15 +-
 src/app/ui/editor/editor_state.h           |   6 +
 src/app/ui/editor/pixels_movement.cpp      |   9 +-
 src/app/ui/palette_view.cpp                | 321 +++++++++---
 src/app/ui/palette_view.h                  |  31 +-
 src/app/util/autocrop.cpp                  |   2 +-
 src/app/util/cel_ops.cpp                   | 540 +++++++++++++++++++++
 src/app/util/cel_ops.h                     |  67 +++
 src/app/util/clipboard.cpp                 |   8 +-
 src/app/util/create_cel_copy.cpp           | 116 -----
 src/app/util/create_cel_copy.h             |  27 --
 src/app/util/expand_cel_canvas.cpp         | 173 +++++--
 src/app/util/expand_cel_canvas.h           |  12 +-
 src/app/util/new_image_from_mask.cpp       |   3 +-
 src/dio/LICENSE.txt                        |   2 +-
 src/dio/aseprite_common.h                  |   2 +
 src/dio/aseprite_decoder.cpp               | 155 ++++--
 src/dio/aseprite_decoder.h                 |   8 +-
 src/dio/pixel_io.h                         |  43 +-
 src/doc/CMakeLists.txt                     |   9 +-
 src/doc/algorithm/fill_selection.cpp       |   1 +
 src/doc/algorithm/shift_image.cpp          |   5 +-
 src/doc/algorithm/shrink_bounds.cpp        | 163 ++++++-
 src/doc/algorithm/shrink_bounds.h          |  22 +-
 src/doc/cel.cpp                            |   5 +-
 src/doc/cel_data.cpp                       |  36 +-
 src/doc/cel_data.h                         |  11 +-
 src/doc/cels_range.cpp                     |   1 +
 src/doc/color_mode.h                       |   4 +-
 src/doc/doc.h                              |   4 +
 src/doc/grid.cpp                           | 163 +++++++
 src/doc/grid.h                             |  76 +++
 src/doc/grid_io.cpp                        |  84 ++++
 src/doc/grid_io.h                          |  22 +
 src/doc/grid_tests.cpp                     |  86 ++++
 src/doc/image.cpp                          |   3 +-
 src/doc/image.h                            |   3 +-
 src/doc/image_io.cpp                       |   7 +-
 src/doc/image_iterator.h                   |   4 +
 src/doc/image_traits.h                     |  32 ++
 src/doc/layer.cpp                          |  17 +-
 src/doc/layer.h                            |   8 +-
 src/doc/layer_io.cpp                       |  17 +-
 src/doc/layer_tilemap.cpp                  |  31 ++
 src/doc/layer_tilemap.h                    |  35 ++
 src/doc/object_type.h                      |   3 +
 src/doc/pixel_format.h                     |  10 +-
 src/doc/primitives.cpp                     |  10 +
 src/doc/primitives.h                       |   1 +
 src/doc/sprite.cpp                         |  19 +-
 src/doc/sprite.h                           |   9 +
 src/doc/tile.h                             |  44 ++
 src/doc/tileset.cpp                        |  45 ++
 src/doc/tileset.h                          |  76 +++
 src/doc/tileset_hash_table.h               |  29 ++
 src/doc/tileset_io.cpp                     |  49 ++
 src/doc/tileset_io.h                       |  29 ++
 src/doc/tilesets.cpp                       |  42 ++
 src/doc/tilesets.h                         |  64 +++
 src/render/render.cpp                      |  81 +++-
 src/render/render.h                        |   1 +
 124 files changed, 4007 insertions(+), 506 deletions(-)
 create mode 100644 src/app/cmd/add_tile.cpp
 create mode 100644 src/app/cmd/add_tile.h
 create mode 100644 src/app/cmd/add_tileset.cpp
 create mode 100644 src/app/cmd/add_tileset.h
 create mode 100644 src/app/cmd/remove_tile.cpp
 create mode 100644 src/app/cmd/remove_tile.h
 create mode 100644 src/app/cmd/remove_tileset.cpp
 create mode 100644 src/app/cmd/remove_tileset.h
 create mode 100644 src/app/cmd/with_tileset.cpp
 create mode 100644 src/app/cmd/with_tileset.h
 create mode 100644 src/app/commands/cmd_toggle_tiles_mode.cpp
 create mode 100644 src/app/script/grid_class.cpp
 create mode 100644 src/app/script/tileset_class.cpp
 create mode 100644 src/app/script/tilesets_class.cpp
 create mode 100644 src/app/tileset_mode.h
 create mode 100644 src/app/util/cel_ops.cpp
 create mode 100644 src/app/util/cel_ops.h
 delete mode 100644 src/app/util/create_cel_copy.cpp
 delete mode 100644 src/app/util/create_cel_copy.h
 create mode 100644 src/doc/grid.cpp
 create mode 100644 src/doc/grid.h
 create mode 100644 src/doc/grid_io.cpp
 create mode 100644 src/doc/grid_io.h
 create mode 100644 src/doc/grid_tests.cpp
 create mode 100644 src/doc/layer_tilemap.cpp
 create mode 100644 src/doc/layer_tilemap.h
 create mode 100644 src/doc/tile.h
 create mode 100644 src/doc/tileset.cpp
 create mode 100644 src/doc/tileset.h
 create mode 100644 src/doc/tileset_hash_table.h
 create mode 100644 src/doc/tileset_io.cpp
 create mode 100644 src/doc/tileset_io.h
 create mode 100644 src/doc/tilesets.cpp
 create mode 100644 src/doc/tilesets.h

diff --git a/data/gui.xml b/data/gui.xml
index c1e9a4287..3934a44a7 100644
--- a/data/gui.xml
+++ b/data/gui.xml
@@ -138,6 +138,7 @@
       <key command="Timeline" shortcut="Tab">
         <param name="switch" value="true" />
       </key>
+      <key command="ToggleTilesMode" shortcut="Shift+Tab" />
       <key command="PaletteEditor" shortcut="A" />
       <key command="PaletteEditor" shortcut="F4">
         <param name="edit" value="switch" />
@@ -807,6 +808,9 @@
             <param name="reference" value="true" />
             <param name="fromFile" value="true" />
           </item>
+          <item command="NewLayer" text="@.layer_new_tilemap_layer">
+            <param name="tilemap" value="true" />
+          </item>
         </menu>
         <item command="RemoveLayer" text="@.layer_delete_layer" />
         <item command="BackgroundFromLayer" text="@.layer_background_from_layer" />
diff --git a/data/pref.xml b/data/pref.xml
index 57a5f2a26..cc83d4dba 100644
--- a/data/pref.xml
+++ b/data/pref.xml
@@ -195,6 +195,7 @@
     </section>
     <section id="color_bar">
       <option id="box_size" type="int" default="11" />
+      <option id="tiles_box_size" type="int" default="16" />
       <option id="fg_color" type="app::Color" default="app::Color::fromRgb(255, 255, 255)" />
       <option id="bg_color" type="app::Color" default="app::Color::fromRgb(0, 0, 0)" />
       <option id="selector" type="app::ColorBar::ColorSelector" default="app::ColorBar::ColorSelector::TINT_SHADE_TONE" />
diff --git a/data/strings/en.ini b/data/strings/en.ini
index e75d44401..d0b266abb 100644
--- a/data/strings/en.ini
+++ b/data/strings/en.ini
@@ -346,6 +346,7 @@ NewLayer_BeforeActiveLayer = New {} Below
 NewLayer_Layer = Layer
 NewLayer_Group = Group
 NewLayer_ReferenceLayer = Reference Layer
+NewLayer_TilemapLayer = Tilemap Layer
 NewLayer_FromClipboard = {} from Clipboard
 NewLayer_ViaCopy = {} via Copy
 NewLayer_ViaCut = {} via Cut
@@ -443,6 +444,7 @@ SymmetryMode = Symmetry Mode
 TiledMode = Tiled Mode
 Timeline = Switch Timeline
 TogglePreview = Toggle Preview
+ToggleTilesMode = Toggle Tiles Mode
 ToggleTimelineThumbnails = Toggle Timeline Thumbnails
 Undo = Undo
 UndoHistory = Undo History
@@ -845,6 +847,7 @@ layer_new_group = New &Group
 layer_new_layer_via_copy = New Layer via &Copy
 layer_new_layer_via_cut = New Layer via Cu&t
 layer_new_reference_layer_from_file = New &Reference Layer from File
+layer_new_tilemap_layer = New Tilemap Layer
 layer_delete_layer = Delete Laye&r
 layer_background_from_layer = &Background from Layer
 layer_layer_from_background = &Layer from Background
diff --git a/docs/ase-file-specs.md b/docs/ase-file-specs.md
index 7199cab89..f8adc9a5e 100644
--- a/docs/ase-file-specs.md
+++ b/docs/ase-file-specs.md
@@ -25,7 +25,9 @@ ASE files use Intel (little-endian) byte order.
 * `PIXEL`: One pixel, depending on the image pixel format:
   - **RGBA**: `BYTE[4]`, each pixel have 4 bytes in this order Red, Green, Blue, Alpha.
   - **Grayscale**: `BYTE[2]`, each pixel have 2 bytes in the order Value, Alpha.
-  - **Indexed**: `BYTE`, Each pixel uses 1 byte (the index).
+  - **Indexed**: `BYTE`, each pixel uses 1 byte (the index).
+* `TILE`: **Tilemaps**: Each tile can be a 8-bit, 16-bit, or 32-bit
+  value and there are masks related to the meaning of each bit.
 
 ## Introduction
 
@@ -146,6 +148,7 @@ Ignore this chunk if you find the new palette chunk (0x2019)
     WORD        Layer type
                   0 = Normal (image) layer
                   1 = Group
+                  2 = Tilemap
     WORD        Layer child level (see NOTE.1)
     WORD        Default layer width in pixels (ignored)
     WORD        Default layer height in pixels (ignored)
@@ -173,19 +176,24 @@ Ignore this chunk if you find the new palette chunk (0x2019)
                   Note: valid only if file header flags field has bit 1 set
     BYTE[3]     For future (set to zero)
     STRING      Layer name
+    + If layer type = 3
+      DWORD     Tileset index
 
 ### Cel Chunk (0x2005)
 
-  This chunk determine where to put a cel in the specified
-  layer/frame.
+This chunk determine where to put a cel in the specified layer/frame.
 
     WORD        Layer index (see NOTE.2)
     SHORT       X position
     SHORT       Y position
     BYTE        Opacity level
-    WORD        Cel type
+    WORD        Cel Type
+                0 - Raw Image Data (unused, compressed image is preferred)
+                1 - Linked Cel
+                2 - Compressed Image
+                3 - Compressed Tilemap
     BYTE[7]     For future (set to zero)
-    + For cel type = 0 (Raw Cel)
+    + For cel type = 0 (Raw Image Data)
       WORD      Width in pixels
       WORD      Height in pixels
       PIXEL[]   Raw pixel data: row by row from top to bottom,
@@ -195,14 +203,18 @@ Ignore this chunk if you find the new palette chunk (0x2019)
     + For cel type = 2 (Compressed Image)
       WORD      Width in pixels
       WORD      Height in pixels
-      BYTE[]    "Raw Cel" data compressed with ZLIB method
-
-Details about the ZLIB and DEFLATE compression methods:
-
-* https://www.ietf.org/rfc/rfc1950
-* https://www.ietf.org/rfc/rfc1951
-* Some extra notes that might help you to decode the data:
-  http://george.chiramattel.com/blog/2007/09/deflatestream-block-length-does-not-match.html
+      BYTE[]    "Raw Cel" data compressed with ZLIB method (see NOTE.3)
+    + For cel type = 3 (Compressed Tilemap)
+      WORD      Width in pixels
+      WORD      Height in pixels
+      WORD      Bits per pixel/tile reference (8, 16, or 32)
+      DWORD     Bitmask for tile ID (e.g. 0x1fffffff for 32-bit tiles)
+      DWORD     Bitmask for X flip
+      DWORD     Bitmask for Y flip
+      DWORD     Bitmask for 90CW rotation
+      BYTE[10]  Reserved
+      TILE[]    Row by row, from top to bottom tile by tile
+                compressed with ZLIB method (see NOTE.3)
 
 ### Cel Extra Chunk (0x2006)
 
@@ -326,6 +338,26 @@ belongs to that cel, etc.
         LONG    Pivot X position (relative to the slice origin)
         LONG    Pivot Y position (relative to the slice origin)
 
+### Tileset Chunk (0x2023)
+
+    DWORD       Tileset ID
+    DWORD       Tileset flags
+                  1 - Include link to external file
+                  2 - Include tiles inside this file
+    WORD        Tiles width
+    WORD        Tiles height
+    BYTE[36]    Reserved
+    STRING      Name of the tileset
+    + If flag 1 is set
+      STRING    Name of the external file (path relative to this file, in the best case)
+      DWORD     Tileset ID in the external file
+    + If flag 2 is set
+      DWORD     Number of tiles to read
+      + For each tile
+        DWORD   Tile flags (0)
+        DWORD   Compressed data length
+        PIXEL[] Read tile image (tile width x height compressed pixels, see NOTE.3)
+
 ### Notes
 
 #### NOTE.1
@@ -356,6 +388,15 @@ example:
       |  `- Layer2                4
       `- Layer3                   5
 
+#### NOTE.3
+
+Details about the ZLIB and DEFLATE compression methods:
+
+* https://www.ietf.org/rfc/rfc1950
+* https://www.ietf.org/rfc/rfc1951
+* Some extra notes that might help you to decode the data:
+  http://george.chiramattel.com/blog/2007/09/deflatestream-block-length-does-not-match.html
+
 ## File Format Changes
 
 1. The first change from the first release of the new .ase format,
diff --git a/src/app/CMakeLists.txt b/src/app/CMakeLists.txt
index a1dc65759..4140d9431 100644
--- a/src/app/CMakeLists.txt
+++ b/src/app/CMakeLists.txt
@@ -160,6 +160,7 @@ if(ENABLE_SCRIPTING)
     script/engine.cpp
     script/frame_class.cpp
     script/frames_class.cpp
+    script/grid_class.cpp
     script/image_class.cpp
     script/image_iterator_class.cpp
     script/image_spec_class.cpp
@@ -184,6 +185,8 @@ if(ENABLE_SCRIPTING)
     script/sprites_class.cpp
     script/tag_class.cpp
     script/tags_class.cpp
+    script/tileset_class.cpp
+    script/tilesets_class.cpp
     script/tool_class.cpp
     script/values.cpp
     script/version_class.cpp
@@ -288,6 +291,7 @@ if(ENABLE_UI)
     commands/cmd_tiled_mode.cpp
     commands/cmd_timeline.cpp
     commands/cmd_toggle_preview.cpp
+    commands/cmd_toggle_tiles_mode.cpp
     commands/cmd_toggle_timeline_thumbnails.cpp
     commands/cmd_undo_history.cpp
     commands/cmd_unlink_cel.cpp
@@ -417,6 +421,8 @@ add_library(app-lib
   cmd/add_palette.cpp
   cmd/add_slice.cpp
   cmd/add_tag.cpp
+  cmd/add_tile.cpp
+  cmd/add_tileset.cpp
   cmd/assign_color_profile.cpp
   cmd/background_from_layer.cpp
   cmd/clear_cel.cpp
@@ -446,6 +452,8 @@ add_library(app-lib
   cmd/remove_palette.cpp
   cmd/remove_slice.cpp
   cmd/remove_tag.cpp
+  cmd/remove_tile.cpp
+  cmd/remove_tileset.cpp
   cmd/replace_image.cpp
   cmd/reselect_mask.cpp
   cmd/set_cel_bounds.cpp
@@ -485,6 +493,7 @@ add_library(app-lib
   cmd/with_slice.cpp
   cmd/with_sprite.cpp
   cmd/with_tag.cpp
+  cmd/with_tileset.cpp
   cmd_sequence.cpp
   cmd_transaction.cpp
   color.cpp
@@ -593,7 +602,7 @@ add_library(app-lib
   ui/layer_frame_comboboxes.cpp
   util/autocrop.cpp
   util/buffer_region.cpp
-  util/create_cel_copy.cpp
+  util/cel_ops.cpp
   util/expand_cel_canvas.cpp
   util/filetoks.cpp
   util/freetype_utils.cpp
diff --git a/src/app/cmd/add_tile.cpp b/src/app/cmd/add_tile.cpp
new file mode 100644
index 000000000..22ba04ad7
--- /dev/null
+++ b/src/app/cmd/add_tile.cpp
@@ -0,0 +1,92 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/cmd/add_tile.h"
+
+#include "doc/image_io.h"
+#include "doc/sprite.h"
+#include "doc/tileset.h"
+#include "doc/tilesets.h"
+
+namespace app {
+namespace cmd {
+
+using namespace doc;
+
+AddTile::AddTile(doc::Tileset* tileset,
+                 const doc::ImageRef& image)
+  : WithTileset(tileset)
+  , WithImage(image.get())
+  , m_size(0)
+  , m_tileIndex(-1)
+  , m_imageRef(image)
+{
+}
+
+AddTile::AddTile(doc::Tileset* tileset,
+                 const doc::tile_index ti)
+  : WithTileset(tileset)
+  , WithImage(tileset->get(ti).get())
+  , m_size(0)
+  , m_tileIndex(ti)
+  , m_imageRef(nullptr)
+{
+}
+
+void AddTile::onExecute()
+{
+  doc::Tileset* tileset = this->tileset();
+  ASSERT(tileset);
+
+  addTile(tileset, m_imageRef);
+
+  m_imageRef.reset();
+}
+
+void AddTile::onUndo()
+{
+  doc::Tileset* tileset = this->tileset();
+  ASSERT(tileset);
+
+  write_image(m_stream, image());
+  m_size = size_t(m_stream.tellp());
+
+  tileset->erase(m_tileIndex);
+
+  tileset->sprite()->incrementVersion();
+  tileset->incrementVersion();
+}
+
+void AddTile::onRedo()
+{
+  doc::Tileset* tileset = this->tileset();
+
+  ASSERT(!m_imageRef);
+  m_imageRef.reset(read_image(m_stream));
+  ASSERT(m_imageRef);
+
+  addTile(tileset, m_imageRef);
+  m_imageRef.reset();
+
+  m_stream.str(std::string());
+  m_stream.clear();
+  m_size = 0;
+}
+
+void AddTile::addTile(doc::Tileset* tileset, const doc::ImageRef& image)
+{
+  m_tileIndex = tileset->add(image);
+
+  tileset->sprite()->incrementVersion();
+  tileset->incrementVersion();
+}
+
+} // namespace cmd
+} // namespace app
diff --git a/src/app/cmd/add_tile.h b/src/app/cmd/add_tile.h
new file mode 100644
index 000000000..8ac5724f5
--- /dev/null
+++ b/src/app/cmd/add_tile.h
@@ -0,0 +1,56 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_CMD_ADD_TILE_H_INCLUDED
+#define APP_CMD_ADD_TILE_H_INCLUDED
+#pragma once
+
+#include "app/cmd.h"
+#include "app/cmd/with_image.h"
+#include "app/cmd/with_tileset.h"
+#include "doc/image_ref.h"
+#include "doc/tile.h"
+
+#include <sstream>
+
+namespace doc {
+  class Tileset;
+}
+
+namespace app {
+namespace cmd {
+
+  class AddTile : public Cmd
+                , public WithTileset
+                , public WithImage {
+  public:
+    AddTile(doc::Tileset* tileset, const doc::ImageRef& image);
+    AddTile(doc::Tileset* tileset, const doc::tile_index ti);
+
+    doc::tile_index tileIndex() const { return m_tileIndex; }
+
+  protected:
+    void onExecute() override;
+    void onUndo() override;
+    void onRedo() override;
+    size_t onMemSize() const override {
+      return sizeof(*this) + m_size;
+    }
+
+  private:
+    void addTile(doc::Tileset* tileset,
+                 const doc::ImageRef& image);
+
+    size_t m_size;
+    std::stringstream m_stream;
+    doc::tile_index m_tileIndex;
+    doc::ImageRef m_imageRef;
+  };
+
+} // namespace cmd
+} // namespace app
+
+#endif
diff --git a/src/app/cmd/add_tileset.cpp b/src/app/cmd/add_tileset.cpp
new file mode 100644
index 000000000..36413b7ee
--- /dev/null
+++ b/src/app/cmd/add_tileset.cpp
@@ -0,0 +1,88 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/cmd/add_tileset.h"
+
+#include "doc/sprite.h"
+#include "doc/subobjects_io.h"
+#include "doc/tileset.h"
+#include "doc/tileset_io.h"
+#include "doc/tilesets.h"
+
+namespace app {
+namespace cmd {
+
+using namespace doc;
+
+AddTileset::AddTileset(doc::Sprite* sprite, doc::Tileset* tileset)
+  : WithSprite(sprite)
+  , WithTileset(tileset)
+  , m_size(0)
+  , m_tilesetIndex(-1)
+{
+}
+
+AddTileset::AddTileset(doc::Sprite* sprite, const doc::tileset_index tsi)
+  : WithSprite(sprite)
+  , WithTileset(sprite->tilesets()->get(tsi))
+  , m_size(0)
+  , m_tilesetIndex(tsi)
+{
+}
+
+void AddTileset::onExecute()
+{
+  Tileset* tileset = this->tileset();
+
+  addTileset(tileset);
+}
+
+void AddTileset::onUndo()
+{
+  doc::Tileset* tileset = this->tileset();
+  write_tileset(m_stream, tileset);
+  m_size = size_t(m_stream.tellp());
+
+  doc::Sprite* sprite = this->sprite();
+  sprite->tilesets()->erase(m_tilesetIndex);
+
+  sprite->incrementVersion();
+  sprite->tilesets()->incrementVersion();
+
+  delete tileset;
+}
+
+void AddTileset::onRedo()
+{
+  SubObjectsFromSprite io(sprite());
+  doc::Tileset* tileset = read_tileset(m_stream, &io);
+
+  addTileset(tileset);
+
+  m_stream.str(std::string());
+  m_stream.clear();
+  m_size = 0;
+}
+
+void AddTileset::addTileset(doc::Tileset* tileset)
+{
+  auto sprite = this->sprite();
+
+  if (m_tilesetIndex == -1)
+    m_tilesetIndex = sprite->tilesets()->add(tileset);
+  else
+    sprite->tilesets()->set(m_tilesetIndex, tileset);
+
+  sprite->incrementVersion();
+  sprite->tilesets()->incrementVersion();
+}
+
+} // namespace cmd
+} // namespace app
diff --git a/src/app/cmd/add_tileset.h b/src/app/cmd/add_tileset.h
new file mode 100644
index 000000000..b3be1c4e5
--- /dev/null
+++ b/src/app/cmd/add_tileset.h
@@ -0,0 +1,53 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_CMD_ADD_TILESET_H_INCLUDED
+#define APP_CMD_ADD_TILESET_H_INCLUDED
+#pragma once
+
+#include "app/cmd.h"
+#include "app/cmd/with_sprite.h"
+#include "app/cmd/with_tileset.h"
+#include "doc/tile.h"
+
+#include <sstream>
+
+namespace doc {
+  class Tileset;
+}
+
+namespace app {
+namespace cmd {
+
+  class AddTileset : public Cmd
+                   , public WithSprite
+                   , public WithTileset {
+  public:
+    AddTileset(doc::Sprite* sprite, doc::Tileset* tileset);
+    AddTileset(doc::Sprite* sprite, const doc::tileset_index tsi);
+
+    doc::tileset_index tilesetIndex() const { return m_tilesetIndex; }
+
+  protected:
+    void onExecute() override;
+    void onUndo() override;
+    void onRedo() override;
+    size_t onMemSize() const override {
+      return sizeof(*this) + m_size;
+    }
+
+  private:
+    void addTileset(doc::Tileset* tileset);
+
+    size_t m_size;
+    std::stringstream m_stream;
+    doc::tileset_index m_tilesetIndex;
+  };
+
+} // namespace cmd
+} // namespace app
+
+#endif
diff --git a/src/app/cmd/copy_cel.cpp b/src/app/cmd/copy_cel.cpp
index 395a1eccb..24cec3661 100644
--- a/src/app/cmd/copy_cel.cpp
+++ b/src/app/cmd/copy_cel.cpp
@@ -19,7 +19,7 @@
 #include "app/cmd/set_cel_data.h"
 #include "app/cmd/unlink_cel.h"
 #include "app/doc.h"
-#include "app/util/create_cel_copy.h"
+#include "app/util/cel_ops.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
 #include "doc/primitives.h"
@@ -32,8 +32,8 @@ namespace cmd {
 using namespace doc;
 
 CopyCel::CopyCel(
-  LayerImage* srcLayer, frame_t srcFrame,
-  LayerImage* dstLayer, frame_t dstFrame, bool continuous)
+  Layer* srcLayer, frame_t srcFrame,
+  Layer* dstLayer, frame_t dstFrame, bool continuous)
   : m_srcLayer(srcLayer)
   , m_dstLayer(dstLayer)
   , m_srcFrame(srcFrame)
@@ -44,8 +44,8 @@ CopyCel::CopyCel(
 
 void CopyCel::onExecute()
 {
-  LayerImage* srcLayer = static_cast<LayerImage*>(m_srcLayer.layer());
-  LayerImage* dstLayer = static_cast<LayerImage*>(m_dstLayer.layer());
+  Layer* srcLayer = m_srcLayer.layer();
+  Layer* dstLayer = m_dstLayer.layer();
 
   ASSERT(srcLayer);
   ASSERT(dstLayer);
@@ -114,7 +114,7 @@ void CopyCel::onExecute()
       if (createLink)
         dstCel = Cel::MakeLink(m_dstFrame, srcCel);
       else
-        dstCel = create_cel_copy(srcCel, dstSprite, dstLayer, m_dstFrame);
+        dstCel = create_cel_copy(this, srcCel, dstSprite, dstLayer, m_dstFrame);
 
       executeAndAdd(new cmd::AddCel(dstLayer, dstCel));
     }
diff --git a/src/app/cmd/copy_cel.h b/src/app/cmd/copy_cel.h
index 689cf3985..a0fd10375 100644
--- a/src/app/cmd/copy_cel.h
+++ b/src/app/cmd/copy_cel.h
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2001-2015  David Capello
 //
 // This program is distributed under the terms of
@@ -13,10 +14,6 @@
 #include "doc/color.h"
 #include "doc/frame.h"
 
-namespace doc {
-  class LayerImage;
-}
-
 namespace app {
 namespace cmd {
   using namespace doc;
@@ -24,8 +21,8 @@ namespace cmd {
   class CopyCel : public CmdSequence {
   public:
     CopyCel(
-      LayerImage* srcLayer, frame_t srcFrame,
-      LayerImage* dstLayer, frame_t dstFrame, bool continuous);
+      Layer* srcLayer, frame_t srcFrame,
+      Layer* dstLayer, frame_t dstFrame, bool continuous);
 
   protected:
     void onExecute() override;
diff --git a/src/app/cmd/crop_cel.cpp b/src/app/cmd/crop_cel.cpp
index 35b361038..d7141c6fe 100644
--- a/src/app/cmd/crop_cel.cpp
+++ b/src/app/cmd/crop_cel.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2016  David Capello
 //
 // This program is distributed under the terms of
@@ -11,6 +12,7 @@
 #include "app/cmd/crop_cel.h"
 
 #include "doc/cel.h"
+#include "doc/layer.h"
 #include "doc/primitives.h"
 
 namespace app {
@@ -22,7 +24,9 @@ CropCel::CropCel(Cel* cel, const gfx::Rect& newBounds)
   : WithCel(cel)
   , m_oldOrigin(cel->position())
   , m_newOrigin(newBounds.origin())
-  , m_oldBounds(cel->bounds())
+  // Instead of using cel->bounds() we use the image size because it
+  // works for tilemaps too.
+  , m_oldBounds(cel->position(), cel->image()->size())
   , m_newBounds(newBounds)
 {
   m_oldBounds.offset(-m_newOrigin);
@@ -59,7 +63,7 @@ void CropCel::cropImage(const gfx::Point& origin,
     image->setId(id);
     image->setVersion(ver);
     image->incrementVersion();
-    cel->data()->setImage(image);
+    cel->data()->setImage(image, cel->layer());
     cel->data()->incrementVersion();
   }
 
diff --git a/src/app/cmd/crop_cel.h b/src/app/cmd/crop_cel.h
index 4dc65c0da..66a98fcc0 100644
--- a/src/app/cmd/crop_cel.h
+++ b/src/app/cmd/crop_cel.h
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2016  David Capello
 //
 // This program is distributed under the terms of
diff --git a/src/app/cmd/flatten_layers.cpp b/src/app/cmd/flatten_layers.cpp
index ff6eab0a7..87a10893f 100644
--- a/src/app/cmd/flatten_layers.cpp
+++ b/src/app/cmd/flatten_layers.cpp
@@ -124,7 +124,7 @@ void FlattenLayers::onExecute()
       else {
         gfx::Rect bounds(image->bounds());
         if (doc::algorithm::shrink_bounds(
-              image.get(), bounds, image->maskColor())) {
+              image.get(), image->maskColor(), nullptr, bounds)) {
           cel_image.reset(
             doc::crop_image(image.get(), bounds, image->maskColor()));
           cel = new Cel(frame, cel_image);
diff --git a/src/app/cmd/move_cel.cpp b/src/app/cmd/move_cel.cpp
index 00fe95970..eb701f0d6 100644
--- a/src/app/cmd/move_cel.cpp
+++ b/src/app/cmd/move_cel.cpp
@@ -20,7 +20,7 @@
 #include "app/cmd/set_cel_frame.h"
 #include "app/cmd/unlink_cel.h"
 #include "app/doc.h"
-#include "app/util/create_cel_copy.h"
+#include "app/util/cel_ops.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
 #include "doc/primitives.h"
@@ -119,7 +119,7 @@ void MoveCel::onExecute()
       executeAndAdd(new cmd::SetCelFrame(srcCel, m_dstFrame));
     }
     else {
-      dstCel = create_cel_copy(srcCel, dstSprite, dstLayer, m_dstFrame);
+      dstCel = create_cel_copy(this, srcCel, dstSprite, dstLayer, m_dstFrame);
 
       executeAndAdd(new cmd::AddCel(dstLayer, dstCel));
       executeAndAdd(new cmd::ClearCel(srcCel));
diff --git a/src/app/cmd/remove_tile.cpp b/src/app/cmd/remove_tile.cpp
new file mode 100644
index 000000000..085657f85
--- /dev/null
+++ b/src/app/cmd/remove_tile.cpp
@@ -0,0 +1,42 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/cmd/remove_tile.h"
+
+#include "doc/cel.h"
+#include "doc/layer.h"
+
+namespace app {
+namespace cmd {
+
+using namespace doc;
+
+RemoveTile::RemoveTile(Tileset* tileset, const tile_index ti)
+  : AddTile(tileset, ti)
+{
+}
+
+void RemoveTile::onExecute()
+{
+  AddTile::onUndo();
+}
+
+void RemoveTile::onUndo()
+{
+  AddTile::onRedo();
+}
+
+void RemoveTile::onRedo()
+{
+  AddTile::onUndo();
+}
+
+} // namespace cmd
+} // namespace app
diff --git a/src/app/cmd/remove_tile.h b/src/app/cmd/remove_tile.h
new file mode 100644
index 000000000..f49fdd71c
--- /dev/null
+++ b/src/app/cmd/remove_tile.h
@@ -0,0 +1,30 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_CMD_REMOVE_TILE_H_INCLUDED
+#define APP_CMD_REMOVE_TILE_H_INCLUDED
+#pragma once
+
+#include "app/cmd/add_tile.h"
+
+namespace app {
+namespace cmd {
+  using namespace doc;
+
+  class RemoveTile : public AddTile {
+  public:
+    RemoveTile(Tileset* tileset, const tile_index ti);
+
+  protected:
+    void onExecute() override;
+    void onUndo() override;
+    void onRedo() override;
+  };
+
+} // namespace cmd
+} // namespace app
+
+#endif
diff --git a/src/app/cmd/remove_tileset.cpp b/src/app/cmd/remove_tileset.cpp
new file mode 100644
index 000000000..1f3b3a3e4
--- /dev/null
+++ b/src/app/cmd/remove_tileset.cpp
@@ -0,0 +1,43 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/cmd/remove_tileset.h"
+
+#include "doc/cel.h"
+#include "doc/layer.h"
+
+namespace app {
+namespace cmd {
+
+using namespace doc;
+
+RemoveTileset::RemoveTileset(Sprite* sprite,
+                             const tileset_index si)
+  : AddTileset(sprite, si)
+{
+}
+
+void RemoveTileset::onExecute()
+{
+  AddTileset::onUndo();
+}
+
+void RemoveTileset::onUndo()
+{
+  AddTileset::onRedo();
+}
+
+void RemoveTileset::onRedo()
+{
+  AddTileset::onUndo();
+}
+
+} // namespace cmd
+} // namespace app
diff --git a/src/app/cmd/remove_tileset.h b/src/app/cmd/remove_tileset.h
new file mode 100644
index 000000000..234e5fec9
--- /dev/null
+++ b/src/app/cmd/remove_tileset.h
@@ -0,0 +1,31 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_CMD_REMOVE_TILESET_H_INCLUDED
+#define APP_CMD_REMOVE_TILESET_H_INCLUDED
+#pragma once
+
+#include "app/cmd/add_tileset.h"
+
+namespace app {
+namespace cmd {
+  using namespace doc;
+
+  class RemoveTileset : public AddTileset {
+  public:
+    RemoveTileset(Sprite* sprite,
+                  const tileset_index si);
+
+  protected:
+    void onExecute() override;
+    void onUndo() override;
+    void onRedo() override;
+  };
+
+} // namespace cmd
+} // namespace app
+
+#endif
diff --git a/src/app/cmd/set_cel_data.cpp b/src/app/cmd/set_cel_data.cpp
index 33bd01cae..031bb1368 100644
--- a/src/app/cmd/set_cel_data.cpp
+++ b/src/app/cmd/set_cel_data.cpp
@@ -14,6 +14,7 @@
 #include "doc/image.h"
 #include "doc/image_io.h"
 #include "doc/image_ref.h"
+#include "doc/layer.h"
 #include "doc/sprite.h"
 #include "doc/subobjects_io.h"
 
@@ -81,7 +82,9 @@ void SetCelData::createCopy()
 
   ASSERT(!m_dataCopy);
   m_dataCopy.reset(new CelData(*cel->data()));
-  m_dataCopy->setImage(ImageRef(Image::createCopy(cel->image())));
+  m_dataCopy->setImage(
+    ImageRef(Image::createCopy(cel->image())),
+    cel->layer());
 }
 
 } // namespace cmd
diff --git a/src/app/cmd/shift_masked_cel.cpp b/src/app/cmd/shift_masked_cel.cpp
index 37686cd12..2f19e17b1 100644
--- a/src/app/cmd/shift_masked_cel.cpp
+++ b/src/app/cmd/shift_masked_cel.cpp
@@ -59,7 +59,7 @@ void ShiftMaskedCel::shift(int dx, int dy)
     newImage->setId(id);
     newImage->setVersion(ver);
     newImage->incrementVersion();
-    cel->data()->setImage(newImage);
+    cel->data()->setImage(newImage, cel->layer());
   }
   cel->data()->setBounds(newBounds);
   cel->data()->incrementVersion();
diff --git a/src/app/cmd/trim_cel.cpp b/src/app/cmd/trim_cel.cpp
index 44f1d7603..81cf979f8 100644
--- a/src/app/cmd/trim_cel.cpp
+++ b/src/app/cmd/trim_cel.cpp
@@ -25,9 +25,7 @@ using namespace doc;
 TrimCel::TrimCel(Cel* cel)
 {
   gfx::Rect newBounds;
-  if (algorithm::shrink_bounds(cel->image(), newBounds,
-                               cel->image()->maskColor())) {
-    newBounds.offset(cel->position());
+  if (algorithm::shrink_cel_bounds(cel, cel->image()->maskColor(), newBounds)) {
     if (cel->bounds() != newBounds) {
       add(new cmd::CropCel(cel, newBounds));
     }
diff --git a/src/app/cmd/unlink_cel.cpp b/src/app/cmd/unlink_cel.cpp
index 95057f859..5437588c6 100644
--- a/src/app/cmd/unlink_cel.cpp
+++ b/src/app/cmd/unlink_cel.cpp
@@ -12,6 +12,7 @@
 
 #include "doc/cel.h"
 #include "doc/image.h"
+#include "doc/layer.h"
 #include "doc/sprite.h"
 
 namespace app {
@@ -36,7 +37,7 @@ void UnlinkCel::onExecute()
 
   ImageRef imgCopy(Image::createCopy(oldCelData->image()));
   CelDataRef celDataCopy(new CelData(*oldCelData));
-  celDataCopy->setImage(imgCopy);
+  celDataCopy->setImage(imgCopy, cel->layer());
   celDataCopy->setUserData(oldCelData->userData());
 
   if (m_newImageId) {
diff --git a/src/app/cmd/with_tileset.cpp b/src/app/cmd/with_tileset.cpp
new file mode 100644
index 000000000..bad3e74ed
--- /dev/null
+++ b/src/app/cmd/with_tileset.cpp
@@ -0,0 +1,31 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/cmd/with_tileset.h"
+
+#include "doc/tileset.h"
+
+namespace app {
+namespace cmd {
+
+using namespace doc;
+
+WithTileset::WithTileset(Tileset* tileset)
+  : m_tilesetId(tileset->id())
+{
+}
+
+Tileset* WithTileset::tileset()
+{
+  return get<Tileset>(m_tilesetId);
+}
+
+} // namespace cmd
+} // namespace app
diff --git a/src/app/cmd/with_tileset.h b/src/app/cmd/with_tileset.h
new file mode 100644
index 000000000..03295fe6b
--- /dev/null
+++ b/src/app/cmd/with_tileset.h
@@ -0,0 +1,32 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_CMD_WITH_TILESET_H_INCLUDED
+#define APP_CMD_WITH_TILESET_H_INCLUDED
+#pragma once
+
+#include "doc/object_id.h"
+
+namespace doc {
+  class Tileset;
+}
+
+namespace app {
+namespace cmd {
+
+  class WithTileset {
+  public:
+    WithTileset(doc::Tileset* tileset);
+    doc::Tileset* tileset();
+
+  private:
+    doc::ObjectId m_tilesetId;
+  };
+
+} // namespace cmd
+} // namespace app
+
+#endif
diff --git a/src/app/cmd_sequence.h b/src/app/cmd_sequence.h
index f3936a400..43f00a62b 100644
--- a/src/app/cmd_sequence.h
+++ b/src/app/cmd_sequence.h
@@ -21,16 +21,16 @@ namespace app {
 
     void add(Cmd* cmd);
 
+    // Helper to create a CmdSequence in the same onExecute() member
+    // function.
+    void executeAndAdd(Cmd* cmd);
+
   protected:
     void onExecute() override;
     void onUndo() override;
     void onRedo() override;
     size_t onMemSize() const override;
 
-    // Helper to create a CmdSequence in the same onExecute() member
-    // function.
-    void executeAndAdd(Cmd* cmd);
-
   private:
     std::vector<Cmd*> m_cmds;
   };
diff --git a/src/app/commands/cmd_clear_cel.cpp b/src/app/commands/cmd_clear_cel.cpp
index 002a746a7..48624649d 100644
--- a/src/app/commands/cmd_clear_cel.cpp
+++ b/src/app/commands/cmd_clear_cel.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -61,11 +62,9 @@ void ClearCelCommand::onExecute(Context* context)
           continue;
         }
 
-        LayerImage* layerImage = static_cast<LayerImage*>(layer);
-
         for (frame_t frame : site->selectedFrames().reversed()) {
-          if (layerImage->cel(frame))
-            document->getApi(tx).clearCel(layerImage, frame);
+          if (Cel* cel = layer->cel(frame))
+            document->getApi(tx).clearCel(cel);
         }
       }
     }
diff --git a/src/app/commands/cmd_fill_and_stroke.cpp b/src/app/commands/cmd_fill_and_stroke.cpp
index a0e8f972d..ed01e9860 100644
--- a/src/app/commands/cmd_fill_and_stroke.cpp
+++ b/src/app/commands/cmd_fill_and_stroke.cpp
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2018  David Capello
 //
 // This program is distributed under the terms of
diff --git a/src/app/commands/cmd_mask_content.cpp b/src/app/commands/cmd_mask_content.cpp
index df624bdc6..84ec57cb1 100644
--- a/src/app/commands/cmd_mask_content.cpp
+++ b/src/app/commands/cmd_mask_content.cpp
@@ -75,8 +75,8 @@ void MaskContentCommand::onExecute(Context* context)
 
     Mask newMask;
     gfx::Rect imgBounds = cel->image()->bounds();
-    if (algorithm::shrink_bounds(cel->image(), imgBounds, color)) {
-      newMask.replace(imgBounds.offset(cel->bounds().origin()));
+    if (algorithm::shrink_cel_bounds(cel, color, imgBounds)) {
+      newMask.replace(imgBounds);
     }
     else {
       newMask.replace(cel->bounds());
diff --git a/src/app/commands/cmd_new_layer.cpp b/src/app/commands/cmd_new_layer.cpp
index 54c56514e..0ef48c35b 100644
--- a/src/app/commands/cmd_new_layer.cpp
+++ b/src/app/commands/cmd_new_layer.cpp
@@ -10,6 +10,7 @@
 #endif
 
 #include "app/app.h"
+#include "app/cmd/add_tileset.h"
 #include "app/cmd/clear_mask.h"
 #include "app/cmd/move_layer.h"
 #include "app/cmd/trim_cel.h"
@@ -30,6 +31,7 @@
 #include "app/util/clipboard.h"
 #include "app/util/new_image_from_mask.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/primitives.h"
 #include "doc/sprite.h"
 #include "fmt/format.h"
@@ -52,6 +54,7 @@ struct NewLayerParams : public NewParams {
   Param<std::string> name { this, std::string(), "name" };
   Param<bool> group { this, false, "group" };
   Param<bool> reference { this, false, "reference" };
+  Param<bool> tilemap { this, false, "tilemap" };
   Param<bool> ask { this, false, "ask" };
   Param<bool> fromFile { this, false, { "fromFile", "from-file" } };
   Param<bool> fromClipboard { this, false, "fromClipboard" };
@@ -63,7 +66,7 @@ struct NewLayerParams : public NewParams {
 
 class NewLayerCommand : public CommandWithNewParams<NewLayerParams> {
 public:
-  enum class Type { Layer, Group, ReferenceLayer };
+  enum class Type { Layer, Group, ReferenceLayer, TilemapLayer };
   enum class Place { AfterActiveLayer, BeforeActiveLayer, Top };
 
   NewLayerCommand();
@@ -98,6 +101,10 @@ void NewLayerCommand::onLoadParams(const Params& commandParams)
     m_type = Type::Group;
   else if (params().reference())
     m_type = Type::ReferenceLayer;
+  else if (params().tilemap())
+    m_type = Type::TilemapLayer;
+  else
+    m_type = Type::Layer;
 
   m_place = Place::AfterActiveLayer;
   if (params().top())
@@ -232,6 +239,20 @@ void NewLayerCommand::onExecute(Context* context)
           layer->setReference(true);
         afterBackground = true;
         break;
+      case Type::TilemapLayer: {
+        // TODO show a dialog to configure the grid
+        auto grid = doc::Grid::MakeRect(gfx::Size(16, 16));
+        auto tileset = new Tileset(sprite, grid, 0);
+        auto addTileset = new cmd::AddTileset(sprite, tileset);
+        tx(addTileset);
+
+        auto tsi = addTileset->tilesetIndex();
+
+        layer = new LayerTilemap(sprite, tsi);
+        layer->setName(name);
+        api.addLayer(parent, layer, parent->lastLayer());
+        break;
+      }
     }
 
     ASSERT(layer);
@@ -460,6 +481,7 @@ std::string NewLayerCommand::layerPrefix() const
     case Type::Layer: return Strings::commands_NewLayer_Layer();
     case Type::Group: return Strings::commands_NewLayer_Group();
     case Type::ReferenceLayer: return Strings::commands_NewLayer_ReferenceLayer();
+    case Type::TilemapLayer: return Strings::commands_NewLayer_TilemapLayer();
   }
   return "Unknown";
 }
diff --git a/src/app/commands/cmd_toggle_tiles_mode.cpp b/src/app/commands/cmd_toggle_tiles_mode.cpp
new file mode 100644
index 000000000..a5721c2d2
--- /dev/null
+++ b/src/app/commands/cmd_toggle_tiles_mode.cpp
@@ -0,0 +1,42 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/app.h"
+#include "app/commands/command.h"
+#include "app/ui/color_bar.h"
+
+namespace app {
+
+using namespace gfx;
+
+class ToggleTilesModeCommand : public Command {
+public:
+  ToggleTilesModeCommand()
+    : Command(CommandId::ToggleTilesMode(), CmdUIOnlyFlag) {
+  }
+
+protected:
+  bool onChecked(Context* context) override {
+    auto colorBar = ColorBar::instance();
+    return colorBar->inTilesMode();
+  }
+
+  void onExecute(Context* context) override {
+    auto colorBar = ColorBar::instance();
+    colorBar->setTilesMode(!colorBar->inTilesMode());
+  }
+};
+
+Command* CommandFactory::createToggleTilesModeCommand()
+{
+  return new ToggleTilesModeCommand;
+}
+
+} // namespace app
diff --git a/src/app/commands/commands_list.h b/src/app/commands/commands_list.h
index 062d0850f..e022faf3d 100644
--- a/src/app/commands/commands_list.h
+++ b/src/app/commands/commands_list.h
@@ -156,6 +156,7 @@ FOR_EACH_COMMAND(SymmetryMode)
 FOR_EACH_COMMAND(TiledMode)
 FOR_EACH_COMMAND(Timeline)
 FOR_EACH_COMMAND(TogglePreview)
+FOR_EACH_COMMAND(ToggleTilesMode)
 FOR_EACH_COMMAND(ToggleTimelineThumbnails)
 FOR_EACH_COMMAND(UndoHistory)
 FOR_EACH_COMMAND(UnlinkCel)
diff --git a/src/app/doc.cpp b/src/app/doc.cpp
index 7df281c50..7a07c78c8 100644
--- a/src/app/doc.cpp
+++ b/src/app/doc.cpp
@@ -23,7 +23,7 @@
 #include "app/file/format_options.h"
 #include "app/flatten.h"
 #include "app/pref/preferences.h"
-#include "app/util/create_cel_copy.h"
+#include "app/util/cel_ops.h"
 #include "base/memory.h"
 #include "doc/cel.h"
 #include "doc/layer.h"
@@ -213,6 +213,13 @@ void Doc::notifySelectionBoundariesChanged()
   notify_observers<DocEvent&>(&DocObserver::onSelectionBoundariesChanged, ev);
 }
 
+void Doc::notifyTilesetChanged(Tileset* tileset)
+{
+  DocEvent ev(this);
+  ev.tileset(tileset);
+  notify_observers<DocEvent&>(&DocObserver::onTilesetChanged, ev);
+}
+
 bool Doc::isModified() const
 {
   return !m_undo->isSavedState();
@@ -395,7 +402,8 @@ void Doc::copyLayerContent(const Layer* sourceLayer0, Doc* destDoc, Layer* destL
                                    it->second));
       }
       else {
-        newCel.reset(create_cel_copy(sourceCel,
+        newCel.reset(create_cel_copy(nullptr, // TODO add undo information?
+                                     sourceCel,
                                      destLayer->sprite(),
                                      destLayer,
                                      sourceCel->frame()));
diff --git a/src/app/doc.h b/src/app/doc.h
index 78995f0c4..dde6f5872 100644
--- a/src/app/doc.h
+++ b/src/app/doc.h
@@ -34,6 +34,7 @@ namespace doc {
   class Mask;
   class MaskBoundaries;
   class Sprite;
+  class Tileset;
 }
 
 namespace gfx {
@@ -103,6 +104,7 @@ namespace app {
     void notifyCelCopied(Layer* fromLayer, frame_t fromFrame, Layer* toLayer, frame_t toFrame);
     void notifySelectionChanged();
     void notifySelectionBoundariesChanged();
+    void notifyTilesetChanged(Tileset* tileset);
 
     //////////////////////////////////////////////////////////////////////
     // File related properties
diff --git a/src/app/doc_api.cpp b/src/app/doc_api.cpp
index 1da070c67..b748e4b34 100644
--- a/src/app/doc_api.cpp
+++ b/src/app/doc_api.cpp
@@ -277,8 +277,8 @@ bool DocApi::cropCel(LayerImage* layer,
       // Try to shrink the image ignoring transparent borders
       gfx::Rect frameBounds;
       if (doc::algorithm::shrink_bounds(newImage.get(),
-                                        frameBounds,
-                                        newImage->maskColor())) {
+                                        newImage->maskColor(), nullptr,
+                                        frameBounds)) {
         // In this case the new cel image can be even smaller
         if (frameBounds != newImage->bounds()) {
           newImage = ImageRef(
@@ -534,8 +534,9 @@ void DocApi::setCelOpacity(Sprite* sprite, Cel* cel, int newOpacity)
   m_transaction.execute(new cmd::SetCelOpacity(cel, newOpacity));
 }
 
-void DocApi::clearCel(LayerImage* layer, frame_t frame)
+void DocApi::clearCel(Layer* layer, frame_t frame)
 {
+  ASSERT(layer->isImage());
   if (Cel* cel = layer->cel(frame))
     clearCel(cel);
 }
@@ -692,7 +693,11 @@ Layer* DocApi::duplicateLayerAfter(Layer* sourceLayer, LayerGroup* parent, Layer
   ASSERT(parent);
   std::unique_ptr<Layer> newLayerPtr;
 
-  if (sourceLayer->isImage())
+  if (sourceLayer->isTilemap()) {
+    newLayerPtr.reset(new LayerTilemap(sourceLayer->sprite(),
+                                       static_cast<LayerTilemap*>(sourceLayer)->tilesetIndex()));
+  }
+  else if (sourceLayer->isImage())
     newLayerPtr.reset(new LayerImage(sourceLayer->sprite()));
   else if (sourceLayer->isGroup())
     newLayerPtr.reset(new LayerGroup(sourceLayer->sprite()));
diff --git a/src/app/doc_api.h b/src/app/doc_api.h
index 7637ddcaa..15f7da751 100644
--- a/src/app/doc_api.h
+++ b/src/app/doc_api.h
@@ -75,7 +75,7 @@ namespace app {
     // Cels API
     void addCel(LayerImage* layer, Cel* cel);
     Cel* addCel(LayerImage* layer, frame_t frameNumber, const ImageRef& image);
-    void clearCel(LayerImage* layer, frame_t frame);
+    void clearCel(Layer* layer, frame_t frame);
     void clearCel(Cel* cel);
     void clearCelAndAllLinks(Cel* cel);
     void setCelPosition(Sprite* sprite, Cel* cel, int x, int y);
diff --git a/src/app/doc_event.h b/src/app/doc_event.h
index ac90e0a89..0859d2ac7 100644
--- a/src/app/doc_event.h
+++ b/src/app/doc_event.h
@@ -20,6 +20,7 @@ namespace doc {
   class Slice;
   class Sprite;
   class Tag;
+  class Tileset;
 }
 
 namespace app {
@@ -37,6 +38,7 @@ namespace app {
       , m_frame(0)
       , m_tag(nullptr)
       , m_slice(nullptr)
+      , m_tileset(nullptr)
       , m_targetLayer(nullptr)
       , m_targetFrame(0) {
     }
@@ -51,6 +53,7 @@ namespace app {
     doc::frame_t frame() const { return m_frame; }
     doc::Tag* tag() const { return m_tag; }
     doc::Slice* slice() const { return m_slice; }
+    doc::Tileset* tileset() const { return m_tileset; }
     const gfx::Region& region() const { return m_region; }
 
     void sprite(doc::Sprite* sprite) { m_sprite = sprite; }
@@ -61,6 +64,7 @@ namespace app {
     void frame(doc::frame_t frame) { m_frame = frame; }
     void tag(doc::Tag* tag) { m_tag = tag; }
     void slice(doc::Slice* slice) { m_slice = slice; }
+    void tileset(doc::Tileset* tileset) { m_tileset = tileset; }
     void region(const gfx::Region& rgn) { m_region = rgn; }
 
     // Destination of the operation.
@@ -80,6 +84,7 @@ namespace app {
     doc::frame_t m_frame;
     doc::Tag* m_tag;
     doc::Slice* m_slice;
+    doc::Tileset* m_tileset;
     gfx::Region m_region;
 
     // For copy/move commands, the m_layer/m_frame are source of the
diff --git a/src/app/doc_exporter.cpp b/src/app/doc_exporter.cpp
index af024326e..9bf7d3913 100644
--- a/src/app/doc_exporter.cpp
+++ b/src/app/doc_exporter.cpp
@@ -955,7 +955,11 @@ void DocExporter::captureSamples(Samples& samples,
         else if (m_ignoreEmptyCels)
           refColor = sprite->transparentColor();
 
-        if (!algorithm::shrink_bounds(sampleRender.get(), spriteBounds, frameBounds, refColor)) {
+          if (!algorithm::shrink_bounds(sampleRender.get(),
+                                        refColor,
+                                        nullptr,        // layer
+                                        spriteBounds,   // startBounds
+                                        frameBounds)) { // output bounds
           // If shrink_bounds() returns false, it's because the whole
           // image is transparent (equal to the mask color).
 
diff --git a/src/app/doc_observer.h b/src/app/doc_observer.h
index 8d2a29477..5ed3de52c 100644
--- a/src/app/doc_observer.h
+++ b/src/app/doc_observer.h
@@ -76,6 +76,9 @@ namespace app {
     // Slices
     virtual void onSliceNameChange(DocEvent& ev) { }
 
+    // The tileset has changed.
+    virtual void onTilesetChanged(DocEvent& ev) { }
+
     // Called to destroy the observable. (Here you could call "delete this".)
     virtual void dispose() { }
   };
diff --git a/src/app/file/ase_format.cpp b/src/app/file/ase_format.cpp
index f674249c9..73491dc43 100644
--- a/src/app/file/ase_format.cpp
+++ b/src/app/file/ase_format.cpp
@@ -127,6 +127,13 @@ static void ase_file_write_slice_chunks(FILE* f, dio::AsepriteFrameHeader* frame
 static void ase_file_write_slice_chunk(FILE* f, dio::AsepriteFrameHeader* frame_header, Slice* slice,
                                        const frame_t fromFrame, const frame_t toFrame);
 static void ase_file_write_user_data_chunk(FILE* f, dio::AsepriteFrameHeader* frame_header, const UserData* userData);
+static void ase_file_write_tileset_chunks(FILE* f,
+                                          dio::AsepriteFrameHeader* frame_header,
+                                          const Tilesets* tilesets);
+static void ase_file_write_tileset_chunk(FILE* f,
+                                         dio::AsepriteFrameHeader* frame_header,
+                                         const Tileset* tileset,
+                                         const tileset_index si);
 static bool ase_has_groups(LayerGroup* group);
 static void ase_ungroup_all(LayerGroup* group);
 
@@ -305,6 +312,9 @@ bool AseFormat::onSave(FileOp* fop)
 
     // Write extra chunks in the first frame
     if (frame == fop->roi().fromFrame()) {
+      // Write tilesets
+      ase_file_write_tileset_chunks(f, &frame_header, sprite->tilesets());
+
       // Write layer chunks
       for (Layer* child : sprite->root()->layers())
         ase_file_write_layers(f, &frame_header, child, 0);
@@ -315,7 +325,7 @@ bool AseFormat::onSave(FileOp* fop)
                                   fop->roi().fromFrame(),
                                   fop->roi().toFrame());
 
-      // Writer slice chunks
+      // Write slice chunks
       ase_file_write_slice_chunks(f, &frame_header,
                                   sprite->slices(),
                                   fop->roi().fromFrame(),
@@ -585,8 +595,15 @@ static void ase_file_write_layer_chunk(FILE* f, dio::AsepriteFrameHeader* frame_
         static_cast<int>(doc::LayerFlags::PersistentFlagsMask), f);
 
   // Layer type
-  fputw((layer->isImage() ? ASE_FILE_LAYER_IMAGE:
-         (layer->isGroup() ? ASE_FILE_LAYER_GROUP: -1)), f);
+  int layerType = ASE_FILE_LAYER_IMAGE;
+  if (layer->isImage()) {
+    if (layer->isTilemap())
+      layerType = ASE_FILE_LAYER_TILEMAP;
+  }
+  else if (layer->isGroup()) {
+    layerType = ASE_FILE_LAYER_GROUP;
+  }
+  fputw(layerType, f);
 
   // Layer child level
   fputw(child_level, f);
@@ -602,6 +619,10 @@ static void ase_file_write_layer_chunk(FILE* f, dio::AsepriteFrameHeader* frame_
 
   // Layer name
   ase_file_write_string(f, layer->name());
+
+  // Tileset index
+  if (layer->isTilemap())
+    fputl(static_cast<const LayerTilemap*>(layer)->tilesetIndex(), f);
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -624,14 +645,12 @@ public:
     fputc(rgba_getb(c), f);
     fputc(rgba_geta(c), f);
   }
-  void write_scanline(RgbTraits::address_t address, int w, uint8_t* buffer)
-  {
-    for (int x=0; x<w; ++x) {
+  void write_scanline(RgbTraits::address_t address, int w, uint8_t* buffer) {
+    for (int x=0; x<w; ++x, ++address) {
       *(buffer++) = rgba_getr(*address);
       *(buffer++) = rgba_getg(*address);
       *(buffer++) = rgba_getb(*address);
       *(buffer++) = rgba_geta(*address);
-      ++address;
     }
   }
 };
@@ -643,12 +662,10 @@ public:
     fputc(graya_getv(c), f);
     fputc(graya_geta(c), f);
   }
-  void write_scanline(GrayscaleTraits::address_t address, int w, uint8_t* buffer)
-  {
-    for (int x=0; x<w; ++x) {
+  void write_scanline(GrayscaleTraits::address_t address, int w, uint8_t* buffer) {
+    for (int x=0; x<w; ++x, ++address) {
       *(buffer++) = graya_getv(*address);
       *(buffer++) = graya_geta(*address);
-      ++address;
     }
   }
 };
@@ -659,12 +676,27 @@ public:
   void write_pixel(FILE* f, IndexedTraits::pixel_t c) {
     fputc(c, f);
   }
-  void write_scanline(IndexedTraits::address_t address, int w, uint8_t* buffer)
-  {
+  void write_scanline(IndexedTraits::address_t address, int w, uint8_t* buffer) {
     memcpy(buffer, address, w);
   }
 };
 
+template<>
+class PixelIO<TilemapTraits> {
+public:
+  void write_pixel(FILE* f, TilemapTraits::pixel_t c) {
+    fputl(c, f);
+  }
+  void write_scanline(TilemapTraits::address_t address, int w, uint8_t* buffer) {
+    for (int x=0; x<w; ++x, ++address) {
+      *(buffer++) = ((*address) & 0x000000ffl);
+      *(buffer++) = ((*address) & 0x0000ff00l) >> 8;
+      *(buffer++) = ((*address) & 0x00ff0000l) >> 16;
+      *(buffer++) = ((*address) & 0xff000000l) >> 24;
+    }
+  }
+};
+
 //////////////////////////////////////////////////////////////////////
 // Raw Image
 //////////////////////////////////////////////////////////////////////
@@ -685,7 +717,7 @@ static void write_raw_image(FILE* f, const Image* image)
 //////////////////////////////////////////////////////////////////////
 
 template<typename ImageTraits>
-static void write_compressed_image(FILE* f, const Image* image)
+static void write_compressed_image_templ(FILE* f, const Image* image)
 {
   PixelIO<ImageTraits> pixel_io;
   z_stream zstream;
@@ -734,6 +766,27 @@ static void write_compressed_image(FILE* f, const Image* image)
     throw base::Exception("ZLib error %d in deflateEnd().", err);
 }
 
+static void write_compressed_image(FILE* f, const Image* image)
+{
+  switch (image->pixelFormat()) {
+    case IMAGE_RGB:
+      write_compressed_image_templ<RgbTraits>(f, image);
+      break;
+
+    case IMAGE_GRAYSCALE:
+      write_compressed_image_templ<GrayscaleTraits>(f, image);
+      break;
+
+    case IMAGE_INDEXED:
+      write_compressed_image_templ<IndexedTraits>(f, image);
+      break;
+
+    case IMAGE_TILEMAP:
+      write_compressed_image_templ<TilemapTraits>(f, image);
+      break;
+  }
+}
+
 //////////////////////////////////////////////////////////////////////
 // Cel Chunk
 //////////////////////////////////////////////////////////////////////
@@ -762,7 +815,9 @@ static void ase_file_write_cel_chunk(FILE* f, dio::AsepriteFrameHeader* frame_he
       link = nullptr;
   }
 
-  int cel_type = (link ? ASE_FILE_LINK_CEL: ASE_FILE_COMPRESSED_CEL);
+  int cel_type = (link ? ASE_FILE_LINK_CEL:
+                  cel->layer()->isTilemap() ? ASE_FILE_COMPRESSED_TILEMAP:
+                                              ASE_FILE_COMPRESSED_CEL);
 
   fputw(layer_index, f);
   fputw(cel->x(), f);
@@ -795,6 +850,7 @@ static void ase_file_write_cel_chunk(FILE* f, dio::AsepriteFrameHeader* frame_he
           case IMAGE_INDEXED:
             write_raw_image<IndexedTraits>(f, image);
             break;
+
         }
       }
       else {
@@ -812,27 +868,12 @@ static void ase_file_write_cel_chunk(FILE* f, dio::AsepriteFrameHeader* frame_he
 
     case ASE_FILE_COMPRESSED_CEL: {
       const Image* image = cel->image();
-
+      ASSERT(image);
       if (image) {
         // Width and height
         fputw(image->width(), f);
         fputw(image->height(), f);
-
-        // Pixel data
-        switch (image->pixelFormat()) {
-
-          case IMAGE_RGB:
-            write_compressed_image<RgbTraits>(f, image);
-            break;
-
-          case IMAGE_GRAYSCALE:
-            write_compressed_image<GrayscaleTraits>(f, image);
-            break;
-
-          case IMAGE_INDEXED:
-            write_compressed_image<IndexedTraits>(f, image);
-            break;
-        }
+        write_compressed_image(f, image);
       }
       else {
         // Width and height
@@ -841,6 +882,23 @@ static void ase_file_write_cel_chunk(FILE* f, dio::AsepriteFrameHeader* frame_he
       }
       break;
     }
+
+    case ASE_FILE_COMPRESSED_TILEMAP: {
+      const Image* image = cel->image();
+      ASSERT(image);
+      ASSERT(image->pixelFormat() == IMAGE_TILEMAP);
+
+      fputw(image->width(), f);
+      fputw(image->height(), f);
+      fputw(32, f);             // TODO use different bpp when possible
+      fputl(tile_i_mask, f);
+      fputl(tile_f_flipx, f);
+      fputl(tile_f_flipy, f);
+      fputl(tile_f_90cw, f);
+      ase_file_write_padding(f, 10);
+
+      write_compressed_image(f, image);
+    }
   }
 }
 
@@ -1085,6 +1143,48 @@ static void ase_file_write_slice_chunk(FILE* f, dio::AsepriteFrameHeader* frame_
   }
 }
 
+static void ase_file_write_tileset_chunks(FILE* f,
+                                          dio::AsepriteFrameHeader* frame_header,
+                                          const Tilesets* tilesets)
+{
+  tileset_index si = 0;
+  for (const Tileset* tileset : *tilesets) {
+    ase_file_write_tileset_chunk(f, frame_header, tileset, si);
+    ++si;
+  }
+}
+
+static void ase_file_write_tileset_chunk(FILE* f,
+                                         dio::AsepriteFrameHeader* frame_header,
+                                         const Tileset* tileset,
+                                         const tileset_index si)
+{
+  ChunkWriter chunk(f, frame_header, ASE_FILE_CHUNK_TILESET);
+
+  fputl(si, f);             // Tileset ID
+  fputl(2, f);              // Tileset Flags (2=include tiles inside file)
+  fputw(tileset->grid().tileSize().w, f);
+  fputw(tileset->grid().tileSize().h, f);
+  ase_file_write_padding(f, 20);
+  ase_file_write_string(f, tileset->name()); // tileset name
+
+  // Flag 2 = tileset
+  fputl(tileset->size(), f);
+  for (tile_index i=0; i<tileset->size(); ++i) {
+    fputl(0, f);                // Flags (zero)
+    size_t beg = ftell(f);
+    fputl(0, f);
+
+    ImageRef tileImg = tileset->get(i);
+    write_compressed_image(f, tileImg.get());
+
+    size_t end = ftell(f);
+    fseek(f, beg, SEEK_SET);
+    fputl(end-beg-4, f);          // Save the compressed data length
+    fseek(f, end, SEEK_SET);
+  }
+}
+
 static bool ase_has_groups(LayerGroup* group)
 {
   for (Layer* child : group->layers()) {
diff --git a/src/app/file/file.cpp b/src/app/file/file.cpp
index 1059adaeb..197e47f9b 100644
--- a/src/app/file/file.cpp
+++ b/src/app/file/file.cpp
@@ -597,7 +597,8 @@ void FileOp::operate(IFileOpProgress* progress)
       auto add_image = [&]() {
         canvasSize |= m_seq.image->size();
 
-        m_seq.last_cel->data()->setImage(m_seq.image);
+        m_seq.last_cel->data()->setImage(m_seq.image,
+                                         m_seq.layer);
         m_seq.layer->addCel(m_seq.last_cel);
 
         if (m_document->sprite()->palette(frame)
diff --git a/src/app/file/gif_format.cpp b/src/app/file/gif_format.cpp
index 2cc9141ed..202a14b38 100644
--- a/src/app/file/gif_format.cpp
+++ b/src/app/file/gif_format.cpp
@@ -693,7 +693,7 @@ private:
     try {
       ImageRef celImage(Image::createCopy(m_currentImage.get()));
       try {
-        cel->data()->setImage(celImage);
+        cel->data()->setImage(celImage, m_layer);
       }
       catch (...) {
         throw;
diff --git a/src/app/script/app_object.cpp b/src/app/script/app_object.cpp
index f44338727..ee181139e 100644
--- a/src/app/script/app_object.cpp
+++ b/src/app/script/app_object.cpp
@@ -311,6 +311,13 @@ int App_useTool(lua_State* L)
   if (!brush)
     brush.reset(new Brush(BrushType::kCircleBrushType, 1, 0));
 
+  // How the tileset must be modified depending on this tool usage
+  type = lua_getfield(L, 1, "tilesetMode");
+  if (type != LUA_TNIL) {
+    site.tilesetMode(TilesetMode(lua_tointeger(L, -1)));
+  }
+  lua_pop(L, 1);
+
   // Do the tool loop
   type = lua_getfield(L, 1, "points");
   if (type == LUA_TTABLE) {
diff --git a/src/app/script/engine.cpp b/src/app/script/engine.cpp
index 5759af94e..c54c47480 100644
--- a/src/app/script/engine.cpp
+++ b/src/app/script/engine.cpp
@@ -18,6 +18,7 @@
 #include "app/script/luacpp.h"
 #include "app/script/security.h"
 #include "app/sprite_sheet_type.h"
+#include "app/tileset_mode.h"
 #include "base/chrono.h"
 #include "base/file_handle.h"
 #include "base/fs.h"
@@ -152,6 +153,7 @@ void register_color_space_class(lua_State* L);
 void register_dialog_class(lua_State* L);
 void register_frame_class(lua_State* L);
 void register_frames_class(lua_State* L);
+void register_grid_class(lua_State* L);
 void register_image_class(lua_State* L);
 void register_image_iterator_class(lua_State* L);
 void register_image_spec_class(lua_State* L);
@@ -172,6 +174,8 @@ void register_sprite_class(lua_State* L);
 void register_sprites_class(lua_State* L);
 void register_tag_class(lua_State* L);
 void register_tags_class(lua_State* L);
+void register_tileset_class(lua_State* L);
+void register_tilesets_class(lua_State* L);
 void register_tool_class(lua_State* L);
 void register_version_class(lua_State* L);
 
@@ -250,6 +254,7 @@ Engine::Engine()
   setfield_integer(L, "GRAY", doc::ColorMode::GRAYSCALE);
   setfield_integer(L, "GRAYSCALE", doc::ColorMode::GRAYSCALE);
   setfield_integer(L, "INDEXED", doc::ColorMode::INDEXED);
+  setfield_integer(L, "TILEMAP", doc::ColorMode::TILEMAP);
   lua_pop(L, 1);
 
   lua_newtable(L);
@@ -341,6 +346,14 @@ Engine::Engine()
   setfield_integer(L, "GRAYA",   TARGET_GRAY_CHANNEL | TARGET_ALPHA_CHANNEL);
   lua_pop(L, 1);
 
+  lua_newtable(L);
+  lua_pushvalue(L, -1);
+  lua_setglobal(L, "TilesetMode");
+  setfield_integer(L, "LOCKED", TilesetMode::Locked);
+  setfield_integer(L, "MODIFY_EXISTENT", TilesetMode::ModifyExistent);
+  setfield_integer(L, "GENERATE_ALL_TILES", TilesetMode::GenerateAllTiles);
+  lua_pop(L, 1);
+
   // Register classes/prototypes
   register_brush_class(L);
   register_cel_class(L);
@@ -350,6 +363,7 @@ Engine::Engine()
   register_dialog_class(L);
   register_frame_class(L);
   register_frames_class(L);
+  register_grid_class(L);
   register_image_class(L);
   register_image_iterator_class(L);
   register_image_spec_class(L);
@@ -370,6 +384,8 @@ Engine::Engine()
   register_sprites_class(L);
   register_tag_class(L);
   register_tags_class(L);
+  register_tileset_class(L);
+  register_tilesets_class(L);
   register_tool_class(L);
   register_version_class(L);
 
diff --git a/src/app/script/engine.h b/src/app/script/engine.h
index 0860e773e..561a0bf86 100644
--- a/src/app/script/engine.h
+++ b/src/app/script/engine.h
@@ -44,6 +44,8 @@ namespace doc {
   class Palette;
   class Sprite;
   class Tag;
+  class Tileset;
+  class Tilesets;
   class WithUserData;
 }
 
@@ -142,6 +144,9 @@ namespace app {
   void push_sprite_slices(lua_State* L, doc::Sprite* sprite);
   void push_sprite_tags(lua_State* L, doc::Sprite* sprite);
   void push_sprites(lua_State* L);
+  void push_tileset(lua_State* L, doc::Tileset* tileset);
+  void push_tileset_image(lua_State* L, doc::Tileset* tileset, doc::Image* image);
+  void push_tilesets(lua_State* L, doc::Tilesets* tilesets);
   void push_tool(lua_State* L, tools::Tool* tool);
   void push_userdata(lua_State* L, doc::WithUserData* userData);
   void push_version(lua_State* L, const base::Version& ver);
diff --git a/src/app/script/grid_class.cpp b/src/app/script/grid_class.cpp
new file mode 100644
index 000000000..a473bcce1
--- /dev/null
+++ b/src/app/script/grid_class.cpp
@@ -0,0 +1,94 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/script/docobj.h"
+#include "app/script/engine.h"
+#include "app/script/luacpp.h"
+#include "doc/grid.h"
+
+namespace app {
+namespace script {
+
+using namespace doc;
+
+namespace {
+
+doc::Grid Grid_new(lua_State* L, int index)
+{
+  doc::Grid grid;
+  // Copy other size
+  if (auto grid2 = may_get_obj<doc::Grid>(L, index)) {
+    grid = *grid2;
+  }
+  // Convert Rectangle into a Grid
+  else if (lua_istable(L, index)) {
+    gfx::Rect rect = convert_args_into_rect(L, index);
+    doc::Grid grid(rect.size());
+    grid.origin(rect.origin());
+  }
+  return grid;
+}
+
+int Grid_new(lua_State* L)
+{
+  push_obj(L, Grid_new(L, 1));
+  return 1;
+}
+
+int Grid_gc(lua_State* L)
+{
+  get_obj<doc::Grid>(L, 1)->~Grid();
+  return 0;
+}
+
+int Grid_get_tileSize(lua_State* L)
+{
+  auto grid = get_obj<doc::Grid>(L, 1);
+  push_obj(L, grid->tileSize());
+  return 1;
+}
+
+int Grid_get_origin(lua_State* L)
+{
+  auto grid = get_obj<doc::Grid>(L, 1);
+  push_obj(L, grid->origin());
+  return 1;
+}
+
+const luaL_Reg Grid_methods[] = {
+  { "__gc", Grid_gc },
+  { nullptr, nullptr }
+};
+
+const Property Grid_properties[] = {
+  { "tileSize", Grid_get_tileSize, nullptr },
+  { "origin", Grid_get_origin, nullptr },
+  { nullptr, nullptr, nullptr }
+};
+
+} // anonymous namespace
+
+DEF_MTNAME(Grid);
+
+void register_grid_class(lua_State* L)
+{
+  using Grid = doc::Grid;
+  REG_CLASS(L, Grid);
+  REG_CLASS_NEW(L, Grid);
+  REG_CLASS_PROPERTIES(L, Grid);
+}
+
+doc::Grid convert_args_into_grid(lua_State* L, int index)
+{
+  return Grid_new(L, index);
+}
+
+} // namespace script
+} // namespace app
diff --git a/src/app/script/image_class.cpp b/src/app/script/image_class.cpp
index 19ab5fe9d..5eec1bb71 100644
--- a/src/app/script/image_class.cpp
+++ b/src/app/script/image_class.cpp
@@ -43,6 +43,7 @@ namespace {
 struct ImageObj {
   doc::ObjectId imageId = 0;
   doc::ObjectId celId = 0;
+  doc::ObjectId tilesetId = 0;
   ImageObj(doc::Image* image)
     : imageId(image->id()) {
   }
@@ -50,6 +51,10 @@ struct ImageObj {
     : imageId(cel->image()->id())
     , celId(cel->id()) {
   }
+  ImageObj(doc::Tileset* tileset, doc::Image* image)
+    : imageId(image->id())
+    , tilesetId(tileset->id()) {
+  }
   ImageObj(const ImageObj&) = delete;
   ImageObj& operator=(const ImageObj&) = delete;
 
@@ -58,7 +63,7 @@ struct ImageObj {
   }
 
   void gc(lua_State* L) {
-    if (!celId)
+    if (!celId && !tilesetId)
       delete this->image(L);
     imageId = 0;
   }
@@ -551,6 +556,11 @@ void push_image(lua_State* L, doc::Image* image)
   push_new<ImageObj>(L, image);
 }
 
+void push_tileset_image(lua_State* L, doc::Tileset* tileset, doc::Image* image)
+{
+  push_new<ImageObj>(L, tileset, image);
+}
+
 doc::Image* may_get_image_from_arg(lua_State* L, int index)
 {
   auto obj = may_get_obj<ImageObj>(L, index);
diff --git a/src/app/script/layer_class.cpp b/src/app/script/layer_class.cpp
index 518e790df..9d51a597b 100644
--- a/src/app/script/layer_class.cpp
+++ b/src/app/script/layer_class.cpp
@@ -21,6 +21,7 @@
 #include "app/tx.h"
 #include "base/clamp.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/sprite.h"
 
 namespace app {
@@ -152,6 +153,13 @@ int Layer_get_isGroup(lua_State* L)
   return 1;
 }
 
+int Layer_get_isTilemap(lua_State* L)
+{
+  auto layer = get_docobj<Layer>(L, 1);
+  lua_pushboolean(L, layer->isTilemap());
+  return 1;
+}
+
 int Layer_get_isTransparent(lua_State* L)
 {
   auto layer = get_docobj<Layer>(L, 1);
@@ -208,6 +216,16 @@ int Layer_get_cels(lua_State* L)
   return 1;
 }
 
+int Layer_get_tileset(lua_State* L)
+{
+  auto layer = get_docobj<Layer>(L, 1);
+  if (layer->isTilemap())
+    push_tileset(L, static_cast<doc::LayerTilemap*>(layer)->tileset());
+  else
+    lua_pushnil(L);
+  return 1;
+}
+
 int Layer_set_name(lua_State* L)
 {
   auto layer = get_docobj<Layer>(L, 1);
@@ -366,6 +384,7 @@ const Property Layer_properties[] = {
   { "blendMode", Layer_get_blendMode, Layer_set_blendMode },
   { "isImage", Layer_get_isImage, nullptr },
   { "isGroup", Layer_get_isGroup, nullptr },
+  { "isTilemap", Layer_get_isTilemap, nullptr },
   { "isTransparent", Layer_get_isTransparent, nullptr },
   { "isBackground", Layer_get_isBackground, nullptr },
   { "isEditable", Layer_get_isEditable, Layer_set_isEditable },
@@ -376,6 +395,7 @@ const Property Layer_properties[] = {
   { "cels", Layer_get_cels, nullptr },
   { "color", UserData_get_color<Layer>, UserData_set_color<Layer> },
   { "data", UserData_get_text<Layer>, UserData_set_text<Layer> },
+  { "tileset", Layer_get_tileset, nullptr },
   { nullptr, nullptr, nullptr }
 };
 
diff --git a/src/app/script/pixel_color_object.cpp b/src/app/script/pixel_color_object.cpp
index 2d4fbb55e..63d01c192 100644
--- a/src/app/script/pixel_color_object.cpp
+++ b/src/app/script/pixel_color_object.cpp
@@ -10,6 +10,7 @@
 
 #include "app/script/luacpp.h"
 #include "doc/color.h"
+#include "doc/tile.h"
 
 namespace app {
 namespace script {
@@ -70,6 +71,26 @@ int PixelColor_grayaA(lua_State* L)
   return 1;
 }
 
+int PixelColor_tile(lua_State* L)
+{
+  const int i = lua_tointeger(L, 1);
+  const int f = lua_tointeger(L, 2);
+  lua_pushinteger(L, doc::tile(i, f));
+  return 1;
+}
+
+int PixelColor_tileI(lua_State* L)
+{
+  lua_pushinteger(L, doc::tile_geti(lua_tointeger(L, 1)));
+  return 1;
+}
+
+int PixelColor_tileF(lua_State* L)
+{
+  lua_pushinteger(L, doc::tile_getf(lua_tointeger(L, 1)));
+  return 1;
+}
+
 const luaL_Reg PixelColor_methods[] = {
   { "rgba", PixelColor_rgba },
   { "rgbaR", PixelColor_rgbaR },
@@ -79,6 +100,9 @@ const luaL_Reg PixelColor_methods[] = {
   { "graya", PixelColor_graya },
   { "grayaV", PixelColor_grayaV },
   { "grayaA", PixelColor_grayaA },
+  { "tile", PixelColor_tile },
+  { "tileI", PixelColor_tileI },
+  { "tileF", PixelColor_tileF },
   { nullptr, nullptr }
 };
 
diff --git a/src/app/script/sprite_class.cpp b/src/app/script/sprite_class.cpp
index f8e241815..dfa3c9539 100644
--- a/src/app/script/sprite_class.cpp
+++ b/src/app/script/sprite_class.cpp
@@ -662,6 +662,13 @@ int Sprite_get_slices(lua_State* L)
   return 1;
 }
 
+int Sprite_get_tilesets(lua_State* L)
+{
+  auto sprite = get_docobj<Sprite>(L, 1);
+  push_tilesets(L, sprite->tilesets());
+  return 1;
+}
+
 int Sprite_get_backgroundLayer(lua_State* L)
 {
   auto sprite = get_docobj<Sprite>(L, 1);
@@ -799,6 +806,7 @@ const Property Sprite_properties[] = {
   { "cels", Sprite_get_cels, nullptr },
   { "tags", Sprite_get_tags, nullptr },
   { "slices", Sprite_get_slices, nullptr },
+  { "tilesets", Sprite_get_tilesets, nullptr },
   { "backgroundLayer", Sprite_get_backgroundLayer, nullptr },
   { "transparentColor", Sprite_get_transparentColor, Sprite_set_transparentColor },
   { "bounds", Sprite_get_bounds, nullptr },
diff --git a/src/app/script/tileset_class.cpp b/src/app/script/tileset_class.cpp
new file mode 100644
index 000000000..2015ee465
--- /dev/null
+++ b/src/app/script/tileset_class.cpp
@@ -0,0 +1,104 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/script/docobj.h"
+#include "app/script/engine.h"
+#include "app/script/luacpp.h"
+#include "doc/tileset.h"
+
+namespace app {
+namespace script {
+
+using namespace doc;
+
+namespace {
+
+int Tileset_eq(lua_State* L)
+{
+  const auto a = get_docobj<Tileset>(L, 1);
+  const auto b = get_docobj<Tileset>(L, 2);
+  lua_pushboolean(L, a->id() == b->id());
+  return 1;
+}
+
+int Tileset_len(lua_State* L)
+{
+  auto tileset = get_docobj<Tileset>(L, 1);
+  lua_pushinteger(L, tileset->size());
+  return 1;
+}
+
+int Tileset_getTile(lua_State* L)
+{
+  auto tileset = get_docobj<Tileset>(L, 1);
+  tile_index i = lua_tointeger(L, 2);
+  ImageRef image = tileset->get(i);
+  if (image)
+    push_tileset_image(L, tileset, image.get());
+  else
+    lua_pushnil(L);
+  return 1;
+}
+
+int Tileset_get_name(lua_State* L)
+{
+  auto tileset = get_docobj<Tileset>(L, 1);
+  lua_pushstring(L, tileset->name().c_str());
+  return 1;
+}
+
+int Tileset_set_name(lua_State* L)
+{
+  auto tileset = get_docobj<Tileset>(L, 1);
+  if (const char* newName = lua_tostring(L, 2))
+    tileset->setName(newName);
+  return 0;
+}
+
+int Tileset_get_grid(lua_State* L)
+{
+  auto tileset = get_docobj<Tileset>(L, 1);
+  push_obj(L, tileset->grid());
+  return 1;
+}
+
+const luaL_Reg Tileset_methods[] = {
+  { "__eq", Tileset_eq },
+  { "__len", Tileset_len },
+  { "getTile", Tileset_getTile },
+  // TODO
+  // { "setTile", Tileset_setTile },
+  { nullptr, nullptr }
+};
+
+const Property Tileset_properties[] = {
+  { "name", Tileset_get_name, Tileset_set_name },
+  { "grid", Tileset_get_grid, nullptr },
+  { nullptr, nullptr, nullptr }
+};
+
+} // anonymous namespace
+
+DEF_MTNAME(Tileset);
+
+void register_tileset_class(lua_State* L)
+{
+  using Tileset = doc::Tileset;
+  REG_CLASS(L, Tileset);
+  REG_CLASS_PROPERTIES(L, Tileset);
+}
+
+void push_tileset(lua_State* L, Tileset* tileset)
+{
+  push_docobj(L, tileset);
+}
+
+} // namespace script
+} // namespace app
diff --git a/src/app/script/tilesets_class.cpp b/src/app/script/tilesets_class.cpp
new file mode 100644
index 000000000..437be52ec
--- /dev/null
+++ b/src/app/script/tilesets_class.cpp
@@ -0,0 +1,62 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/script/docobj.h"
+#include "app/script/engine.h"
+#include "app/script/luacpp.h"
+#include "doc/tilesets.h"
+
+namespace app {
+namespace script {
+
+using namespace doc;
+
+namespace {
+
+int Tilesets_len(lua_State* L)
+{
+  auto obj = get_docobj<Tilesets>(L, 1);
+  lua_pushinteger(L, obj->size());
+  return 1;
+}
+
+int Tilesets_index(lua_State* L)
+{
+  auto obj = get_docobj<Tilesets>(L, 1);
+  const int i = lua_tonumber(L, 2);
+  if (i >= 1 && i <= int(obj->size()))
+    push_docobj(L, *(obj->begin()+i-1));
+  else
+    lua_pushnil(L);
+  return 1;
+}
+
+const luaL_Reg Tilesets_methods[] = {
+  { "__len", Tilesets_len },
+  { "__index", Tilesets_index },
+  { nullptr, nullptr }
+};
+
+} // anonymous namespace
+
+DEF_MTNAME(Tilesets);
+
+void register_tilesets_class(lua_State* L)
+{
+  REG_CLASS(L, Tilesets);
+}
+
+void push_tilesets(lua_State* L, Tilesets* tilesets)
+{
+  push_docobj(L, tilesets);
+}
+
+} // namespace script
+} // namespace app
diff --git a/src/app/site.cpp b/src/app/site.cpp
index 214f00653..130f430eb 100644
--- a/src/app/site.cpp
+++ b/src/app/site.cpp
@@ -14,8 +14,11 @@
 #include "app/pref/preferences.h"
 #include "base/base.h"
 #include "doc/cel.h"
+#include "doc/grid.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/sprite.h"
+#include "doc/tileset.h"
 #include "ui/system.h"
 
 namespace app {
@@ -81,6 +84,15 @@ void Site::range(const DocRange& range)
 
 gfx::Rect Site::gridBounds() const
 {
+  if (m_layer && m_layer->isTilemap()) {
+    const Cel* cel = (m_layer ? m_layer->cel(m_frame): nullptr);
+    if (cel) {
+      const Grid& grid = static_cast<LayerTilemap*>(m_layer)->tileset()->grid();
+      return gfx::Rect(grid.tileOffset() + cel->bounds().origin(),
+                       grid.tileSize());
+    }
+  }
+
   gfx::Rect bounds;
   if (m_sprite) {
     bounds = m_sprite->gridBounds();
diff --git a/src/app/site.h b/src/app/site.h
index 013341c69..ad10a780d 100644
--- a/src/app/site.h
+++ b/src/app/site.h
@@ -10,6 +10,7 @@
 #pragma once
 
 #include "app/doc_range.h"
+#include "app/tileset_mode.h"
 #include "doc/frame.h"
 #include "doc/palette_picks.h"
 #include "doc/selected_objects.h"
@@ -49,7 +50,8 @@ namespace app {
       , m_document(nullptr)
       , m_sprite(nullptr)
       , m_layer(nullptr)
-      , m_frame(0) { }
+      , m_frame(0)
+      , m_tilesetMode(TilesetMode::Locked) { }
 
     const Focus focus() const { return m_focus; }
     bool inEditor() const { return m_focus == InEditor; }
@@ -101,6 +103,9 @@ namespace app {
 
     gfx::Rect gridBounds() const;
 
+    void tilesetMode(const TilesetMode& mode) { m_tilesetMode = mode; }
+    const TilesetMode& tilesetMode() const { return m_tilesetMode; }
+
   private:
     Focus m_focus;
     Doc* m_document;
@@ -110,6 +115,7 @@ namespace app {
     DocRange m_range;
     doc::PalettePicks m_selectedColors;
     doc::SelectedObjects m_selectedSlices;
+    TilesetMode m_tilesetMode;
   };
 
 } // namespace app
diff --git a/src/app/tileset_mode.h b/src/app/tileset_mode.h
new file mode 100644
index 000000000..54c73882d
--- /dev/null
+++ b/src/app/tileset_mode.h
@@ -0,0 +1,24 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_TILES_MODE_H_INCLUDED
+#define APP_TILES_MODE_H_INCLUDED
+#pragma once
+
+namespace app {
+
+  // These modes are available edition modes for the tileset when an
+  // tilemap is edited.
+  enum class TilesetMode {
+    Locked,           // Cannot edit the tileset (don't modify or add new tiles)
+    ModifyExistent,   // Modify existent tiles (don't create new ones)
+    //GenerateNewTiles, // Auto-generate new tiles, edit existent ones
+    GenerateAllTiles, // Auto-generate new and modified tiles
+  };
+
+} // namespace app
+
+#endif
diff --git a/src/app/transaction.h b/src/app/transaction.h
index b577465f2..15a542d74 100644
--- a/src/app/transaction.h
+++ b/src/app/transaction.h
@@ -9,6 +9,7 @@
 #define APP_TRANSACTION_H_INCLUDED
 #pragma once
 
+#include "app/cmd_transaction.h"
 #include "app/doc_observer.h"
 
 #include <string>
@@ -16,7 +17,6 @@
 namespace app {
 
   class Cmd;
-  class CmdTransaction;
   class Context;
   class DocRange;
   class DocUndo;
@@ -82,6 +82,8 @@ namespace app {
 
     void execute(Cmd* cmd);
 
+    CmdTransaction* cmds() { return m_cmds; }
+
   private:
     // List of changes during the execution of this transaction
     enum class Changes {
diff --git a/src/app/tx.h b/src/app/tx.h
index 9f9c483bf..ed980bb87 100644
--- a/src/app/tx.h
+++ b/src/app/tx.h
@@ -73,6 +73,10 @@ namespace app {
       return *m_transaction;
     }
 
+    operator CmdTransaction*() {
+      return m_transaction->cmds();
+    }
+
   private:
     Doc* m_doc;
     Transaction* m_transaction;
diff --git a/src/app/ui/color_bar.cpp b/src/app/ui/color_bar.cpp
index e2777619f..6e6edd188 100644
--- a/src/app/ui/color_bar.cpp
+++ b/src/app/ui/color_bar.cpp
@@ -16,6 +16,7 @@
 #include "app/app.h"
 #include "app/app_menus.h"
 #include "app/cmd/remap_colors.h"
+#include "app/cmd/remove_tile.h"
 #include "app/cmd/replace_image.h"
 #include "app/cmd/set_palette.h"
 #include "app/cmd/set_transparent_color.h"
@@ -27,8 +28,8 @@
 #include "app/commands/quick_command.h"
 #include "app/console.h"
 #include "app/context_access.h"
-#include "app/doc_undo.h"
 #include "app/doc_api.h"
+#include "app/doc_undo.h"
 #include "app/i18n/strings.h"
 #include "app/ini_file.h"
 #include "app/modules/editors.h"
@@ -56,6 +57,7 @@
 #include "doc/cels_range.h"
 #include "doc/image.h"
 #include "doc/image_impl.h"
+#include "doc/layer_tilemap.h"
 #include "doc/palette.h"
 #include "doc/primitives.h"
 #include "doc/remap.h"
@@ -86,6 +88,12 @@ enum class PalButton {
   MAX
 };
 
+enum class TilesButton {
+  MODE,
+  AUTO,
+  MAX
+};
+
 using namespace app::skin;
 using namespace ui;
 
@@ -111,13 +119,24 @@ ColorBar::ScrollableView::ScrollableView()
 
 void ColorBar::ScrollableView::onInitTheme(InitThemeEvent& ev)
 {
+  auto hbar = horizontalBar();
+  auto vbar = verticalBar();
+  setup_mini_look(hbar);
+  setup_mini_look(vbar);
+
+  View::onInitTheme(ev);
+
   SkinTheme* theme = static_cast<SkinTheme*>(this->theme());
   setStyle(theme->styles.colorbarView());
 
-  horizontalBar()->setStyle(theme->styles.miniScrollbar());
-  verticalBar()->setStyle(theme->styles.miniScrollbar());
-  horizontalBar()->setThumbStyle(theme->styles.miniScrollbarThumb());
-  verticalBar()->setThumbStyle(theme->styles.miniScrollbarThumb());
+  hbar->setStyle(theme->styles.miniScrollbar());
+  vbar->setStyle(theme->styles.miniScrollbar());
+  hbar->setThumbStyle(theme->styles.miniScrollbarThumb());
+  vbar->setThumbStyle(theme->styles.miniScrollbarThumb());
+
+  const int scrollBarWidth = theme->dimensions.miniScrollbarSize();
+  hbar->setBarWidth(scrollBarWidth);
+  vbar->setBarWidth(scrollBarWidth);
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -128,8 +147,10 @@ ColorBar* ColorBar::m_instance = NULL;
 ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
   : Box(align)
   , m_buttons(int(PalButton::MAX))
+  , m_tilesButtons(int(TilesButton::MAX))
   , m_splitter(Splitter::ByPercentage, VERTICAL)
   , m_paletteView(true, PaletteView::FgBgColors, this, 16)
+  , m_tilesView(true, PaletteView::FgBgTiles, this, 16)
   , m_remapButton("Remap")
   , m_selector(ColorSelector::NONE)
   , m_tintShadeTone(nullptr)
@@ -144,9 +165,12 @@ ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
   , m_fromFgButton(false)
   , m_fromBgButton(false)
   , m_lastDocument(nullptr)
+  , m_lastTilesetId(doc::NullId)
   , m_ascending(true)
   , m_lastButtons(kButtonLeft)
   , m_editMode(false)
+  , m_tilesMode(false)
+  , m_autoTilesMode(true)
   , m_redrawTimer(250, this)
   , m_redrawAll(false)
   , m_implantChange(false)
@@ -161,17 +185,24 @@ ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
   m_buttons.addItem(theme->parts.palPresets());
   m_buttons.addItem(theme->parts.palOptions());
 
+  m_tilesButtons.addItem("Tiles");
+  m_tilesButtons.addItem("Auto");
+  m_tilesButtons.setVisible(false);
+  m_tilesButtons.getItem((int)TilesButton::AUTO)->setHotColor(theme->colors.editPalFace());
+
   m_paletteView.setColumns(8);
+  m_tilesView.setColumns(8);
 
-  setup_mini_look(m_scrollableView.horizontalBar());
-  setup_mini_look(m_scrollableView.verticalBar());
-
-  m_scrollableView.attachToView(&m_paletteView);
-  m_scrollableView.setExpansive(true);
+  m_scrollablePalView.attachToView(&m_paletteView);
+  m_scrollableTilesView.attachToView(&m_tilesView);
+  m_scrollablePalView.setExpansive(true);
+  m_scrollableTilesView.setExpansive(true);
 
+  m_scrollableTilesView.setVisible(false);
   m_remapButton.setVisible(false);
 
-  m_palettePlaceholder.addChild(&m_scrollableView);
+  m_palettePlaceholder.addChild(&m_scrollablePalView);
+  m_palettePlaceholder.addChild(&m_scrollableTilesView);
   m_palettePlaceholder.addChild(&m_remapButton);
   m_splitter.setId("palette_spectrum_splitter");
   m_splitter.setPosition(80);
@@ -183,6 +214,7 @@ ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
     Preferences::instance().colorBar.selector());
 
   addChild(&m_buttons);
+  addChild(&m_tilesButtons);
   addChild(&m_splitter);
 
   HBox* fgBox = new HBox;
@@ -207,6 +239,7 @@ ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
   m_bgWarningIcon->Click.connect(base::Bind<void>(&ColorBar::onFixWarningClick, this, &m_bgColor, m_bgWarningIcon));
   m_redrawTimer.Tick.connect(base::Bind<void>(&ColorBar::onTimerTick, this));
   m_buttons.ItemChange.connect(base::Bind<void>(&ColorBar::onPaletteButtonClick, this));
+  m_tilesButtons.ItemChange.connect(base::Bind<void>(&ColorBar::onTilesButtonClick, this));
 
   tooltipManager->addTooltipFor(&m_fgColor, "Foreground color", LEFT);
   tooltipManager->addTooltipFor(&m_bgColor, "Background color", LEFT);
@@ -230,17 +263,16 @@ ColorBar::ColorBar(int align, TooltipManager* tooltipManager)
       m_buttons.setMaxSize(gfx::Size(m_buttons.sizeHint().w,
                                      theme->dimensions.colorBarButtonsHeight()));
 
-      int scrollBarWidth = theme->dimensions.miniScrollbarSize();
-      m_scrollableView.horizontalBar()->setBarWidth(scrollBarWidth);
-      m_scrollableView.verticalBar()->setBarWidth(scrollBarWidth);
-
       // Change color-bar background color (not ColorBar::setBgColor)
       this->Widget::setBgColor(theme->colors.tabActiveFace());
       m_paletteView.setBgColor(theme->colors.tabActiveFace());
-      m_paletteView.setBoxSize(
-        Preferences::instance().colorBar.boxSize());
+      m_paletteView.setBoxSize(Preferences::instance().colorBar.boxSize());
       m_paletteView.initTheme();
 
+      m_tilesView.setBgColor(theme->colors.tabActiveFace());
+      m_tilesView.setBoxSize(Preferences::instance().colorBar.tilesBoxSize());
+      m_tilesView.initTheme();
+
       // Styles
       m_splitter.setStyle(theme->styles.workspaceSplitter());
 
@@ -420,6 +452,66 @@ void ColorBar::setEditMode(bool state)
     m_paletteView.deselect();
 }
 
+bool ColorBar::inTilesMode() const
+{
+  return
+    (m_tilesMode &&
+     m_tilesButtons.isVisible() &&
+     m_lastDocument &&
+     m_lastDocument->sprite());
+}
+
+void ColorBar::setTilesMode(bool state)
+{
+  const Site site = UIContext::instance()->activeSite();
+  const bool isTilemap = (site.layer() && site.layer()->isTilemap());
+
+  SkinTheme* theme = static_cast<SkinTheme*>(this->theme());
+  ButtonSet::Item* item = m_tilesButtons.getItem((int)TilesButton::MODE);
+
+  m_tilesMode = state;
+  item->setHotColor(state ? theme->colors.editPalFace(): gfx::ColorNone);
+
+  if (state && isTilemap) {
+    manager()->freeWidget(&m_paletteView);
+    m_scrollablePalView.setVisible(false);
+    m_scrollableTilesView.setVisible(true);
+  }
+  else {
+    manager()->freeWidget(&m_tilesView);
+    m_scrollablePalView.setVisible(true);
+    m_scrollableTilesView.setVisible(false);
+  }
+
+  layout();
+}
+
+bool ColorBar::inAutoTilesMode() const
+{
+  return
+    (m_autoTilesMode &&
+     m_tilesButtons.isVisible() &&
+     m_lastDocument &&
+     m_lastDocument->sprite());
+}
+
+void ColorBar::setAutoTilesMode(bool state)
+{
+  SkinTheme* theme = static_cast<SkinTheme*>(this->theme());
+  ButtonSet::Item* item = m_tilesButtons.getItem((int)TilesButton::AUTO);
+
+  m_autoTilesMode = state;
+  item->setHotColor(state ? theme->colors.editPalFace(): gfx::ColorNone);
+}
+
+TilesetMode ColorBar::tilesetMode() const
+{
+  if (inAutoTilesMode())
+    return TilesetMode::GenerateAllTiles;
+  else
+    return TilesetMode::ModifyExistent;
+}
+
 void ColorBar::onActiveSiteChange(const Site& site)
 {
   if (m_lastDocument != site.document()) {
@@ -433,6 +525,29 @@ void ColorBar::onActiveSiteChange(const Site& site)
 
     hideRemap();
   }
+
+  bool isTilemap = false;
+  if (site.layer()) {
+    isTilemap = site.layer()->isTilemap();
+    if (m_tilesButtons.isVisible() != isTilemap) {
+      m_tilesButtons.setVisible(isTilemap);
+      layout();
+    }
+
+    if (isTilemap) {
+      doc::ObjectId newTilesetId =
+        static_cast<const doc::LayerTilemap*>(site.layer())->tileset()->id();
+      if (m_lastTilesetId != newTilesetId) {
+        m_lastTilesetId = newTilesetId;
+        m_scrollableTilesView.updateView();
+      }
+    }
+  }
+  if (!isTilemap) {
+    m_lastTilesetId = doc::NullId;
+    if (inTilesMode())
+      setTilesMode(m_tilesMode);
+  }
 }
 
 void ColorBar::onGeneralUpdate(DocEvent& ev)
@@ -441,6 +556,13 @@ void ColorBar::onGeneralUpdate(DocEvent& ev)
   invalidate();
 }
 
+void ColorBar::onTilesetChanged(DocEvent& ev)
+{
+  m_tilesButtons.deselectItems();
+  if (m_scrollableTilesView.isVisible())
+    m_scrollableTilesView.updateView();
+}
+
 void ColorBar::onAppPaletteChange()
 {
   COLOR_BAR_TRACE("ColorBar::onAppPaletteChange()\n");
@@ -508,6 +630,24 @@ void ColorBar::onPaletteButtonClick()
   }
 }
 
+void ColorBar::onTilesButtonClick()
+{
+  int item = m_tilesButtons.selectedItem();
+  m_tilesButtons.deselectItems();
+
+  switch (static_cast<TilesButton>(item)) {
+
+    case TilesButton::MODE:
+      setTilesMode(!inTilesMode());
+      break;
+
+    case TilesButton::AUTO:
+      setAutoTilesMode(!inAutoTilesMode());
+      break;
+
+  }
+}
+
 void ColorBar::onRemapButtonClick()
 {
   ASSERT(m_oldPalette);
@@ -589,6 +729,10 @@ void ColorBar::onPaletteViewIndexChange(int index, ui::MouseButtons buttons)
 {
   COLOR_BAR_TRACE("ColorBar::onPaletteViewIndexChange(%d)\n", index);
 
+  // TODO select tiles to stamp
+  if (inTilesMode())
+    return;
+
   base::ScopedValue<bool> lock(m_fromPalView, true, m_fromPalView);
 
   app::Color color = app::Color::fromIndex(index);
@@ -659,7 +803,10 @@ void ColorBar::setTransparentIndex(int index)
 
 void ColorBar::onPaletteViewChangeSize(int boxsize)
 {
-  Preferences::instance().colorBar.boxSize(boxsize);
+  if (inTilesMode())
+    Preferences::instance().colorBar.tilesBoxSize(boxsize);
+  else
+    Preferences::instance().colorBar.boxSize(boxsize);
 }
 
 void ColorBar::onPaletteViewPasteColors(
@@ -714,6 +861,26 @@ app::Color ColorBar::onPaletteViewGetBackgroundIndex()
   return getBgColor();
 }
 
+void ColorBar::onPaletteViewClearTiles(const doc::PalettePicks& picks)
+{
+  try {
+    ContextWriter writer(UIContext::instance(), 500);
+    Sprite* sprite = writer.sprite();
+    ASSERT(writer.layer()->isTilemap());
+    if (sprite) {
+      auto tileset = m_tilesView.tileset();
+
+      Tx tx(writer.context(), "Clear Tiles", ModifyDocument);
+      for (auto ti : picks)
+        tx(new cmd::RemoveTile(tileset, ti));
+      tx.commit();
+    }
+  }
+  catch (base::Exception& e) {
+    Console::showException(e);
+  }
+}
+
 void ColorBar::onFgColorChangeFromPreferences()
 {
   COLOR_BAR_TRACE("ColorBar::onFgColorChangeFromPreferences() -> %s\n",
@@ -998,30 +1165,44 @@ bool ColorBar::onCanClear(Context* ctx)
 
 bool ColorBar::onCut(Context* ctx)
 {
-  m_paletteView.cutToClipboard();
+  if (m_tilesMode)
+    m_tilesView.cutToClipboard();
+  else
+    m_paletteView.cutToClipboard();
   return true;
 }
 
 bool ColorBar::onCopy(Context* ctx)
 {
-  m_paletteView.copyToClipboard();
+  if (m_tilesMode)
+    m_tilesView.copyToClipboard();
+  else
+    m_paletteView.copyToClipboard();
   return true;
 }
 
 bool ColorBar::onPaste(Context* ctx)
 {
-  m_paletteView.pasteFromClipboard();
+  if (m_tilesMode)
+    m_tilesView.pasteFromClipboard();
+  else
+    m_paletteView.pasteFromClipboard();
   return true;
 }
 
 bool ColorBar::onClear(Context* ctx)
 {
-  m_paletteView.clearSelection();
+  if (m_tilesMode)
+    m_tilesView.clearSelection();
+  else
+    m_paletteView.clearSelection();
   return true;
 }
 
 void ColorBar::onCancel(Context* ctx)
 {
+  m_tilesView.deselect();
+  m_tilesView.discardClipboardSelection();
   m_paletteView.deselect();
   m_paletteView.discardClipboardSelection();
   invalidate();
@@ -1207,6 +1388,11 @@ void ColorBar::setupTooltips(TooltipManager* tooltipManager)
   tooltipManager->addTooltipFor(m_buttons.getItem((int)PalButton::PRESETS), "Presets", BOTTOM);
   tooltipManager->addTooltipFor(m_buttons.getItem((int)PalButton::OPTIONS), "Options", BOTTOM);
   tooltipManager->addTooltipFor(&m_remapButton, "Matches old indexes with new indexes", BOTTOM);
+
+  tooltipManager->addTooltipFor(
+    m_tilesButtons.getItem((int)TilesButton::MODE), "Show Tileset", BOTTOM);
+  tooltipManager->addTooltipFor(
+    m_tilesButtons.getItem((int)TilesButton::AUTO), "Generate new tiles automatically", BOTTOM);
 }
 
 // static
diff --git a/src/app/ui/color_bar.h b/src/app/ui/color_bar.h
index 62590a60e..5b0f71dc9 100644
--- a/src/app/ui/color_bar.h
+++ b/src/app/ui/color_bar.h
@@ -13,10 +13,12 @@
 #include "app/context_observer.h"
 #include "app/doc_observer.h"
 #include "app/docs_observer.h"
+#include "app/tileset_mode.h"
 #include "app/ui/button_set.h"
 #include "app/ui/color_button.h"
 #include "app/ui/input_chain_element.h"
 #include "app/ui/palette_view.h"
+#include "doc/object_id.h"
 #include "doc/pixel_format.h"
 #include "doc/sort_palette.h"
 #include "obs/connection.h"
@@ -78,6 +80,14 @@ namespace app {
     bool inEditMode() const;
     void setEditMode(bool state);
 
+    bool inTilesMode() const;
+    void setTilesMode(bool state);
+
+    bool inAutoTilesMode() const;
+    void setAutoTilesMode(bool state);
+
+    TilesetMode tilesetMode() const;
+
     ColorButton* fgColorButton() { return &m_fgColor; }
     ColorButton* bgColorButton() { return &m_bgColor; }
 
@@ -86,6 +96,7 @@ namespace app {
 
     // DocObserver impl
     void onGeneralUpdate(DocEvent& ev) override;
+    void onTilesetChanged(DocEvent& ev) override;
 
     // InputChainElement impl
     void onNewInputPriority(InputChainElement* element,
@@ -108,6 +119,7 @@ namespace app {
     void onBeforeExecuteCommand(CommandExecutionEvent& ev);
     void onAfterExecuteCommand(CommandExecutionEvent& ev);
     void onPaletteButtonClick();
+    void onTilesButtonClick();
     void onRemapButtonClick();
     void onPaletteIndexChange(PaletteIndexChangeEvent& ev);
     void onFgColorChangeFromPreferences();
@@ -131,6 +143,7 @@ namespace app {
     void onPaletteViewPasteColors(const Palette* fromPal, const doc::PalettePicks& from, const doc::PalettePicks& to) override;
     app::Color onPaletteViewGetForegroundIndex() override;
     app::Color onPaletteViewGetBackgroundIndex() override;
+    void onPaletteViewClearTiles(const doc::PalettePicks& picks) override;
 
   private:
     void showRemap();
@@ -157,12 +170,15 @@ namespace app {
     class WarningIcon;
 
     ButtonSet m_buttons;
+    ButtonSet m_tilesButtons;
     std::unique_ptr<PalettePopup> m_palettePopup;
     ui::Splitter m_splitter;
     ui::VBox m_palettePlaceholder;
     ui::VBox m_selectorPlaceholder;
-    ScrollableView m_scrollableView;
+    ScrollableView m_scrollablePalView;
+    ScrollableView m_scrollableTilesView;
     PaletteView m_paletteView;
+    PaletteView m_tilesView;
     ui::Button m_remapButton;
     ColorSelector m_selector;
     ColorTintShadeTone* m_tintShadeTone;
@@ -186,6 +202,7 @@ namespace app {
 
     std::unique_ptr<doc::Palette> m_oldPalette;
     Doc* m_lastDocument;
+    doc::ObjectId m_lastTilesetId;
     bool m_ascending;
     obs::scoped_connection m_beforeCmdConn;
     obs::scoped_connection m_afterCmdConn;
@@ -195,9 +212,13 @@ namespace app {
     obs::scoped_connection m_appPalChangeConn;
     ui::MouseButtons m_lastButtons;
 
-    // True if we the editing mode is on.
+    // True if the editing mode is on.
     bool m_editMode;
 
+    // True if we should be putting/setting tiles.
+    bool m_tilesMode;
+    bool m_autoTilesMode;
+
     // Timer to redraw editors after a palette change.
     ui::Timer m_redrawTimer;
     bool m_redrawAll;
diff --git a/src/app/ui/doc_view.cpp b/src/app/ui/doc_view.cpp
index da7d201cc..b42186eb3 100644
--- a/src/app/ui/doc_view.cpp
+++ b/src/app/ui/doc_view.cpp
@@ -468,6 +468,11 @@ void DocView::onLayerRestacked(DocEvent& ev)
   m_editor->invalidate();
 }
 
+void DocView::onTilesetChanged(DocEvent& ev)
+{
+  m_editor->invalidate();
+}
+
 void DocView::onNewInputPriority(InputChainElement* element,
                                  const ui::Message* msg)
 {
@@ -587,6 +592,7 @@ bool DocView::onClear(Context* ctx)
   if (cels.empty())            // No cels to modify
     return false;
 
+  // TODO This code is similar to clipboard::cut()
   {
     Tx tx(writer.context(), "Clear");
     const bool deselectMask =
diff --git a/src/app/ui/doc_view.h b/src/app/ui/doc_view.h
index 8523ed407..1276addff 100644
--- a/src/app/ui/doc_view.h
+++ b/src/app/ui/doc_view.h
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -79,6 +80,7 @@ namespace app {
     void onRemoveCel(DocEvent& ev) override;
     void onTotalFramesChanged(DocEvent& ev) override;
     void onLayerRestacked(DocEvent& ev) override;
+    void onTilesetChanged(DocEvent& ev) override;
 
     // InputChainElement impl
     void onNewInputPriority(InputChainElement* element,
diff --git a/src/app/ui/editor/drawing_state.cpp b/src/app/ui/editor/drawing_state.cpp
index bfbc410ec..590fd82ab 100644
--- a/src/app/ui/editor/drawing_state.cpp
+++ b/src/app/ui/editor/drawing_state.cpp
@@ -287,6 +287,16 @@ void DrawingState::onExposeSpritePixels(const gfx::Region& rgn)
     m_toolLoop->validateDstImage(rgn);
 }
 
+bool DrawingState::getGridBounds(Editor* editor, gfx::Rect& gridBounds)
+{
+  if (m_toolLoop) {
+    gridBounds = m_toolLoop->getGridBounds();
+    return true;
+  }
+  else
+    return false;
+}
+
 void DrawingState::handleMouseMovement(const tools::Pointer& pointer)
 {
   m_mouseMoveReceived = true;
diff --git a/src/app/ui/editor/drawing_state.h b/src/app/ui/editor/drawing_state.h
index 55a46bac6..5a4702d08 100644
--- a/src/app/ui/editor/drawing_state.h
+++ b/src/app/ui/editor/drawing_state.h
@@ -42,6 +42,8 @@ namespace app {
     // already drawing (viewing the real trace).
     virtual bool requireBrushPreview() override { return false; }
 
+    virtual bool getGridBounds(Editor* editor, gfx::Rect& gridBounds) override;
+
     void initToolLoop(Editor* editor,
                       const tools::Pointer& pointer);
 
diff --git a/src/app/ui/editor/editor.cpp b/src/app/ui/editor/editor.cpp
index f616b06a2..a4a94dcc3 100644
--- a/src/app/ui/editor/editor.cpp
+++ b/src/app/ui/editor/editor.cpp
@@ -382,6 +382,7 @@ void Editor::getSite(Site* site) const
   site->sprite(m_sprite);
   site->layer(m_layer);
   site->frame(m_frame);
+
   if (!m_selectedSlices.empty() &&
       getCurrentEditorInk()->isSlice()) {
     site->selectedSlices(m_selectedSlices);
@@ -393,6 +394,15 @@ void Editor::getSite(Site* site) const
       timeline->range().enabled()) {
     site->range(timeline->range());
   }
+
+  if (m_layer && m_layer->isTilemap()) {
+    TilesetMode mode = site->tilesetMode();
+    const ColorBar* colorbar = ColorBar::instance();
+    ASSERT(colorbar);
+    if (colorbar)
+      mode = colorbar->tilesetMode();
+    site->tilesetMode(mode);
+  }
 }
 
 Site Editor::getSite() const
@@ -737,7 +747,10 @@ void Editor::drawOneSpriteUnclippedRect(ui::Graphics* g, const gfx::Rect& sprite
 
       // Draw the grid
       if (m_docPref.show.grid()) {
-        gfx::Rect gridrc = m_sprite->gridBounds();
+        gfx::Rect gridrc;
+        if (!m_state->getGridBounds(this, gridrc))
+          gridrc = getSite().gridBounds();
+
         if (m_proj.applyX(gridrc.w) > 2 &&
             m_proj.applyY(gridrc.h) > 2) {
           int alpha = m_docPref.grid.opacity();
diff --git a/src/app/ui/editor/editor_state.h b/src/app/ui/editor/editor_state.h
index 440de8d16..47c3f2579 100644
--- a/src/app/ui/editor/editor_state.h
+++ b/src/app/ui/editor/editor_state.h
@@ -10,6 +10,8 @@
 #pragma once
 
 #include "base/disable_copying.h"
+#include "base/shared_ptr.h"
+#include "gfx/fwd.h"
 #include "gfx/point.h"
 
 #include <memory>
@@ -132,6 +134,10 @@ namespace app {
     // Called when a tag is deleted.
     virtual void onRemoveTag(Editor* editor, doc::Tag* tag) { }
 
+    // Used to adjust the grid origin point for temporal cels created
+    // by states like DrawingState + ExpandCelCanvas.
+    virtual bool getGridBounds(Editor* editor, gfx::Rect& gridBounds) { return false; }
+
   private:
     DISABLE_COPYING(EditorState);
   };
diff --git a/src/app/ui/editor/pixels_movement.cpp b/src/app/ui/editor/pixels_movement.cpp
index 76e4545b1..989e50cd5 100644
--- a/src/app/ui/editor/pixels_movement.cpp
+++ b/src/app/ui/editor/pixels_movement.cpp
@@ -26,6 +26,7 @@
 #include "app/ui/editor/pivot_helpers.h"
 #include "app/ui/status_bar.h"
 #include "app/ui_context.h"
+#include "app/util/cel_ops.h"
 #include "app/util/expand_cel_canvas.h"
 #include "app/util/new_image_from_mask.h"
 #include "app/util/range_utils.h"
@@ -278,7 +279,9 @@ void PixelsMovement::cutMask()
   {
     ContextWriter writer(m_reader, 1000);
     if (writer.cel()) {
-      m_tx(new cmd::ClearMask(writer.cel()));
+      clear_mask_from_cel(m_tx,
+                          writer.cel(),
+                          m_site.tilesetMode());
 
       // Do not trim here so we don't lost the information about all
       // linked cels related to "writer.cel()"
@@ -1080,7 +1083,9 @@ void PixelsMovement::reproduceAllTransformationsWithInnerCmds()
   for (const InnerCmd& c : m_innerCmds) {
     switch (c.type) {
       case InnerCmd::Clear:
-        m_tx(new cmd::ClearMask(m_site.cel()));
+        clear_mask_from_cel(m_tx,
+                            m_site.cel(),
+                            m_site.tilesetMode());
         break;
       case InnerCmd::Flip:
         flipOriginalImage(c.data.flip.type);
diff --git a/src/app/ui/palette_view.cpp b/src/app/ui/palette_view.cpp
index 26f4faf2a..e0e53824b 100644
--- a/src/app/ui/palette_view.cpp
+++ b/src/app/ui/palette_view.cpp
@@ -17,21 +17,28 @@
 #include "app/modules/gfx.h"
 #include "app/modules/gui.h"
 #include "app/modules/palettes.h"
+#include "app/site.h"
 #include "app/ui/editor/editor.h"
 #include "app/ui/palette_view.h"
 #include "app/ui/skin/skin_theme.h"
 #include "app/ui/status_bar.h"
+#include "app/ui_context.h"
 #include "app/util/clipboard.h"
 #include "app/util/pal_ops.h"
 #include "base/bind.h"
 #include "base/convert_to.h"
+#include "doc/conversion_to_surface.h"
 #include "doc/image.h"
+#include "doc/layer_tilemap.h"
 #include "doc/palette.h"
 #include "doc/remap.h"
+#include "doc/tileset.h"
 #include "gfx/color.h"
 #include "gfx/point.h"
 #include "os/font.h"
 #include "os/surface.h"
+#include "os/surface.h"
+#include "os/system.h"
 #include "ui/graphics.h"
 #include "ui/manager.h"
 #include "ui/message.h"
@@ -51,12 +58,186 @@ namespace app {
 using namespace ui;
 using namespace app::skin;
 
+// Interface used to adapt the PaletteView widget to see tilesets too.
+class AbstractPaletteViewAdapter {
+public:
+  virtual ~AbstractPaletteViewAdapter() { }
+  virtual int size() const = 0;
+  virtual void paletteChange(doc::PalettePicks& picks) = 0;
+  virtual void activeSiteChange(const Site& site, doc::PalettePicks& picks) = 0;
+  virtual void clearSelection(PaletteView* paletteView,
+                              doc::PalettePicks& picks) = 0;
+  virtual void showEntryInStatusBar(StatusBar* statusBar, int index) = 0;
+  virtual void showDragInfoInStatusBar(StatusBar* statusBar, bool copy, int destIndex, int newSize) = 0;
+  virtual void showResizeInfoInStatusBar(StatusBar* statusBar, int newSize) = 0;
+  virtual void drawEntry(ui::Graphics* g,
+                         SkinTheme* theme,
+                         const int palIdx,
+                         const int offIdx,
+                         const int childSpacing,
+                         gfx::Rect& box,
+                         gfx::Color& negColor) = 0;
+  virtual doc::Tileset* tileset() const { return nullptr; }
+};
+
+// This default adapter uses the default behavior to use the
+// PaletteView as just a doc::Palette view.
+class PaletteViewAdapter : public AbstractPaletteViewAdapter {
+public:
+  int size() const override { return palette()->size(); }
+  void paletteChange(doc::PalettePicks& picks) override {
+    picks.resize(palette()->size());
+  }
+  void activeSiteChange(const Site& site, doc::PalettePicks& picks) override {
+    // Do nothing
+  }
+  void clearSelection(PaletteView* paletteView,
+                      doc::PalettePicks& picks) override {
+    Palette palette(*this->palette());
+    Palette newPalette(palette);
+    newPalette.resize(MAX(1, newPalette.size() - picks.picks()));
+
+    Remap remap = create_remap_to_move_picks(picks, palette.size());
+    for (int i=0; i<palette.size(); ++i) {
+      if (!picks[i])
+        newPalette.setEntry(remap[i], palette.getEntry(i));
+    }
+
+    paletteView->setNewPalette(&palette, &newPalette, PaletteViewModification::CLEAR);
+  }
+  void showEntryInStatusBar(StatusBar* statusBar, int index) override {
+    statusBar->showColor(
+      0, "", app::Color::fromIndex(index));
+  }
+  void showDragInfoInStatusBar(StatusBar* statusBar, bool copy, int destIndex, int newSize) override {
+    statusBar->setStatusText(
+      0, "%s to %d - New Palette Size %d",
+      (copy ? "Copy": "Move"),
+      destIndex, newSize);
+  }
+  void showResizeInfoInStatusBar(StatusBar* statusBar, int newSize) override {
+    statusBar->setStatusText(
+      0, "New Palette Size %d", newSize);
+  }
+  void drawEntry(ui::Graphics* g,
+                 SkinTheme* theme,
+                 const int palIdx,
+                 const int offIdx,
+                 const int childSpacing,
+                 gfx::Rect& box,
+                 gfx::Color& negColor) override {
+    doc::color_t palColor =
+      (palIdx < palette()->size() ? palette()->getEntry(palIdx):
+                                    rgba(0, 0, 0, 255));
+    app::Color appColor = app::Color::fromRgb(
+      rgba_getr(palColor),
+      rgba_getg(palColor),
+      rgba_getb(palColor),
+      rgba_geta(palColor));
+
+    if (childSpacing > 0) {
+      gfx::Color color = theme->colors.paletteEntriesSeparator();
+      g->fillRect(color, gfx::Rect(box).enlarge(childSpacing));
+    }
+    draw_color(g, box, appColor, doc::ColorMode::RGB);
+
+    const gfx::Color gfxColor = gfx::rgba(
+      rgba_getr(palColor),
+      rgba_getg(palColor),
+      rgba_getb(palColor),
+      rgba_geta(palColor));
+    negColor = color_utils::blackandwhite_neg(gfxColor);
+  }
+private:
+  doc::Palette* palette() const {
+    return get_current_palette();
+  }
+};
+
+// This adapter makes it possible to use a PaletteView to edit a
+// doc::Tileset.
+class TilesetViewAdapter : public AbstractPaletteViewAdapter {
+public:
+  int size() const override {
+    if (auto t = tileset())
+      return t->size();
+    else
+      return 0;
+  }
+  void paletteChange(doc::PalettePicks& picks) override {
+    // Do nothing
+  }
+  void activeSiteChange(const Site& site, doc::PalettePicks& picks) override {
+    if (auto tileset = this->tileset())
+      picks.resize(tileset->size());
+    else
+      picks.clear();
+  }
+  void clearSelection(PaletteView* paletteView,
+                      doc::PalettePicks& picks) override {
+    paletteView->delegate()->onPaletteViewClearTiles(picks);
+  }
+  void showEntryInStatusBar(StatusBar* statusBar, int index) override {
+    statusBar->setStatusText(
+      0, "Tile %d", index);
+  }
+  void showDragInfoInStatusBar(StatusBar* statusBar, bool copy, int destIndex, int newSize) override {
+    statusBar->setStatusText(
+      0, "%s to %d - New Tileset Size %d",
+      (copy ? "Copy": "Move"),
+      destIndex, newSize);
+  }
+  void showResizeInfoInStatusBar(StatusBar* statusBar, int newSize) override {
+    statusBar->setStatusText(
+      0, "New Tileset Size %d", newSize);
+  }
+  void drawEntry(ui::Graphics* g,
+                 SkinTheme* theme,
+                 const int palIdx,
+                 const int offIdx,
+                 const int childSpacing,
+                 gfx::Rect& box,
+                 gfx::Color& negColor) override {
+    if (childSpacing > 0) {
+      gfx::Color color = theme->colors.paletteEntriesSeparator();
+      g->fillRect(color, gfx::Rect(box).enlarge(childSpacing));
+    }
+    draw_color(g, box, app::Color::fromMask(), doc::ColorMode::RGB);
+
+    doc::ImageRef tileImage;
+    if (auto t = this->tileset())
+      tileImage = t->get(palIdx);
+    if (tileImage) {
+      int w = tileImage->width();
+      int h = tileImage->height();
+      os::Surface* surface = os::instance()->createRgbaSurface(w, h);
+      doc::convert_image_to_surface(tileImage.get(), get_current_palette(),
+                                    surface, 0, 0, 0, 0, w, h);
+      g->drawRgbaSurface(surface, gfx::Rect(0, 0, w, h), box);
+      surface->dispose();
+    }
+    negColor = gfx::rgba(255, 255, 255);
+  }
+  doc::Tileset* tileset() const override {
+    Site site = App::instance()->context()->activeSite();
+    if (site.layer() &&
+        site.layer()->isTilemap()) {
+      return static_cast<LayerTilemap*>(site.layer())->tileset();
+    }
+    else
+      return nullptr;
+  }
+private:
+};
+
 PaletteView::PaletteView(bool editable, PaletteViewStyle style, PaletteViewDelegate* delegate, int boxsize)
   : Widget(kGenericWidget)
   , m_state(State::WAITING)
   , m_editable(editable)
   , m_style(style)
   , m_delegate(delegate)
+  , m_adapter(isTiles() ? (AbstractPaletteViewAdapter*)new TilesetViewAdapter:
+                          (AbstractPaletteViewAdapter*)new PaletteViewAdapter)
   , m_columns(16)
   , m_boxsize(boxsize)
   , m_currentEntry(-1)
@@ -82,6 +263,9 @@ PaletteView::PaletteView(bool editable, PaletteViewStyle style, PaletteViewDeleg
         });
   }
 
+  if (isTiles())
+    UIContext::instance()->add_observer(this);
+
   InitTheme.connect(
     [this]{
       updateBorderAndChildSpacing();
@@ -89,6 +273,12 @@ PaletteView::PaletteView(bool editable, PaletteViewStyle style, PaletteViewDeleg
   initTheme();
 }
 
+PaletteView::~PaletteView()
+{
+  if (isTiles())
+    UIContext::instance()->remove_observer(this);
+}
+
 void PaletteView::setColumns(int columns)
 {
   int old_columns = m_columns;
@@ -107,7 +297,7 @@ void PaletteView::deselect()
 {
   bool invalidate = (m_selectedEntries.picks() > 0);
 
-  m_selectedEntries.resize(currentPalette()->size());
+  m_selectedEntries.resize(m_adapter->size());
   m_selectedEntries.clear();
 
   if (invalidate)
@@ -116,7 +306,7 @@ void PaletteView::deselect()
 
 void PaletteView::selectColor(int index)
 {
-  if (index < 0 || index >= currentPalette()->size())
+  if (index < 0 || index >= m_adapter->size())
     return;
 
   if (m_currentEntry != index || !m_selectedEntries[index]) {
@@ -202,17 +392,27 @@ void PaletteView::setSelectedEntries(const doc::PalettePicks& entries)
   invalidate();
 }
 
+doc::Tileset* PaletteView::tileset() const
+{
+  return m_adapter->tileset();
+}
+
 app::Color PaletteView::getColorByPosition(const gfx::Point& pos)
 {
   gfx::Point relPos = pos - bounds().origin();
-  Palette* palette = currentPalette();
-  for (int i=0; i<palette->size(); ++i) {
+  for (int i=0; i<m_adapter->size(); ++i) {
     if (getPaletteEntryBounds(i).contains(relPos))
       return app::Color::fromIndex(i);
   }
   return app::Color::fromMask();
 }
 
+void PaletteView::onActiveSiteChange(const Site& site)
+{
+  ASSERT(isTiles());
+  m_adapter->activeSiteChange(site, m_selectedEntries);
+}
+
 int PaletteView::getBoxSize() const
 {
   return int(m_boxsize);
@@ -220,7 +420,10 @@ int PaletteView::getBoxSize() const
 
 void PaletteView::setBoxSize(double boxsize)
 {
-  m_boxsize = MID(4.0, boxsize, 32.0);
+  if (isTiles())
+    m_boxsize = MID(4.0, boxsize, 64.0);
+  else
+    m_boxsize = MID(4.0, boxsize, 32.0);
 
   if (m_delegate)
     m_delegate->onPaletteViewChangeSize(int(m_boxsize));
@@ -235,21 +438,11 @@ void PaletteView::clearSelection()
   if (!m_selectedEntries.picks())
     return;
 
-  Palette palette(*currentPalette());
-  Palette newPalette(palette);
-  newPalette.resize(MAX(1, newPalette.size() - m_selectedEntries.picks()));
-
-  Remap remap = create_remap_to_move_picks(m_selectedEntries, palette.size());
-  for (int i=0; i<palette.size(); ++i) {
-    if (!m_selectedEntries[i])
-      newPalette.setEntry(remap[i], palette.getEntry(i));
-  }
+  m_adapter->clearSelection(this, m_selectedEntries);
 
   m_currentEntry = m_selectedEntries.firstPick();
   m_selectedEntries.clear();
   stopMarchingAnts();
-
-  setNewPalette(&palette, &newPalette, PaletteViewModification::CLEAR);
 }
 
 void PaletteView::cutToClipboard()
@@ -342,7 +535,7 @@ bool PaletteView::onProcessMessage(Message* msg)
       if (m_state == State::SELECTING_COLOR &&
           m_hot.part == Hit::COLOR) {
         int idx = m_hot.color;
-        idx = MID(0, idx, currentPalette()->size()-1);
+        idx = MID(0, idx, m_adapter->size()-1);
 
         MouseButtons buttons = mouseMsg->buttons();
 
@@ -497,11 +690,11 @@ void PaletteView::onPaint(ui::PaintEvent& ev)
 
   g->fillRect(theme->colors.editorFace(), bounds);
 
-  // Draw palette entries
+  // Draw palette/tileset entries
   int picksCount = m_selectedEntries.picks();
   int idxOffset = 0;
   int boxOffset = 0;
-  int palSize = palette->size();
+  int palSize = m_adapter->size();
   if (dragging && !m_copy) palSize -= picksCount;
   if (resizing) palSize = m_hot.color;
 
@@ -519,7 +712,8 @@ void PaletteView::onPaint(ui::PaintEvent& ev)
 
     gfx::Rect box = getPaletteEntryBounds(i + boxOffset);
     gfx::Color negColor;
-    drawEntry(g, i + idxOffset, i + boxOffset, box, negColor);
+    m_adapter->drawEntry(g, theme, i + idxOffset, i + boxOffset,
+                         childSpacing(), box, negColor);
     const int boxsize = boxSizePx();
 
     switch (m_style) {
@@ -570,7 +764,8 @@ void PaletteView::onPaint(ui::PaintEvent& ev)
   }
   PalettePicks& picks = (dragging ? dragPicks: m_selectedEntries);
 
-  for (int i=0; i<palette->size(); ++i) {
+  const int size = m_adapter->size();
+  for (int i=0; i<size; ++i) {
     if (!m_selectedEntries[i])
       continue;
 
@@ -585,13 +780,13 @@ void PaletteView::onPaint(ui::PaintEvent& ev)
       if (dragging) {
         gfx::Rect box2 = getPaletteEntryBounds(k);
         gfx::Color negColor;
-        drawEntry(g, i, k, box2, negColor);
+        m_adapter->drawEntry(g, theme, i, k, childSpacing(),
+                             box2, negColor);
 
-        gfx::Color neg = color_utils::blackandwhite_neg(negColor);
         os::Font* minifont = theme->getMiniFont();
         const std::string text = base::convert_to<std::string>(k);
         g->setFont(minifont);
-        g->drawText(text, neg, gfx::ColorNone,
+        g->drawText(text, negColor, gfx::ColorNone,
                     gfx::Point(box2.x + box2.w/2 - minifont->textLength(text)/2,
                                box2.y + box2.h/2 - minifont->height()/2));
       }
@@ -654,7 +849,7 @@ void PaletteView::onResize(ui::ResizeEvent& ev)
 
 void PaletteView::onSizeHint(ui::SizeHintEvent& ev)
 {
-  div_t d = div(currentPalette()->size(), m_columns);
+  div_t d = div(m_adapter->size(), m_columns);
   int cols = m_columns;
   int rows = d.quot + ((d.rem)? 1: 0);
 
@@ -688,7 +883,7 @@ void PaletteView::update_scroll(int color)
 
   scroll = view->viewScroll();
 
-  d = div(currentPalette()->size(), m_columns);
+  d = div(m_adapter->size(), m_columns);
   cols = m_columns;
 
   y = (boxsize+childSpacing()) * (color / cols);
@@ -709,7 +904,7 @@ void PaletteView::update_scroll(int color)
 
 void PaletteView::onAppPaletteChange()
 {
-  m_selectedEntries.resize(currentPalette()->size());
+  m_adapter->paletteChange(m_selectedEntries);
 
   View* view = View::getView(this);
   if (view)
@@ -734,19 +929,18 @@ PaletteView::Hit PaletteView::hitTest(const gfx::Point& pos)
 {
   auto theme = static_cast<SkinTheme*>(this->theme());
   const int outlineWidth = theme->dimensions.paletteOutlineWidth();
-  Palette* palette = currentPalette();
+  const int size = m_adapter->size();
 
   if (m_state == State::WAITING && m_editable) {
     // First check if the mouse is inside the selection outline.
-    for (int i=0; i<palette->size(); ++i) {
+    for (int i=0; i<size; ++i) {
       if (!m_selectedEntries[i])
         continue;
 
-      const int max = palette->size();
-      bool top    = (i >= m_columns            && i-m_columns >= 0  ? m_selectedEntries[i-m_columns]: false);
-      bool bottom = (i < max-m_columns         && i+m_columns < max ? m_selectedEntries[i+m_columns]: false);
-      bool left   = ((i%m_columns)>0           && i-1         >= 0  ? m_selectedEntries[i-1]: false);
-      bool right  = ((i%m_columns)<m_columns-1 && i+1         < max ? m_selectedEntries[i+1]: false);
+      bool top    = (i >= m_columns             && i-m_columns >= 0   ? m_selectedEntries[i-m_columns]: false);
+      bool bottom = (i < size-m_columns         && i+m_columns < size ? m_selectedEntries[i+m_columns]: false);
+      bool left   = ((i%m_columns)>0            && i-1         >= 0   ? m_selectedEntries[i-1]: false);
+      bool right  = ((i%m_columns)<m_columns-1  && i+1         < size ? m_selectedEntries[i+1]: false);
 
       gfx::Rect box = getPaletteEntryBounds(i);
       box.enlarge(outlineWidth);
@@ -759,17 +953,18 @@ PaletteView::Hit PaletteView::hitTest(const gfx::Point& pos)
     }
 
     // Check if we are in the resize handle
-    if (getPaletteEntryBounds(palette->size()).contains(pos)) {
-      return Hit(Hit::RESIZE_HANDLE, palette->size());
+    if (getPaletteEntryBounds(size).contains(pos)) {
+      return Hit(Hit::RESIZE_HANDLE, size);
     }
   }
 
   // Check if we are inside a color.
   View* view = View::getView(this);
+  ASSERT(view);
   gfx::Rect vp = view->viewportBounds();
   for (int i=0; ; ++i) {
     gfx::Rect box = getPaletteEntryBounds(i);
-    if (i >= palette->size() && box.y2() > vp.h)
+    if (i >= size && box.y2() > vp.h)
       break;
 
     box.w += childSpacing();
@@ -912,11 +1107,10 @@ void PaletteView::setStatusBar()
       if ((m_hot.part == Hit::COLOR ||
            m_hot.part == Hit::OUTLINE ||
            m_hot.part == Hit::POSSIBLE_COLOR) &&
-          (m_hot.color < currentPalette()->size())) {
-        int i = MAX(0, m_hot.color);
+          (m_hot.color < m_adapter->size())) {
+        const int index = MAX(0, m_hot.color);
 
-        statusBar->showColor(
-          0, "", app::Color::fromIndex(i));
+        m_adapter->showEntryInStatusBar(statusBar, index);
       }
       else {
         statusBar->showDefaultText();
@@ -927,15 +1121,13 @@ void PaletteView::setStatusBar()
       if (m_hot.part == Hit::COLOR) {
         const int picks = m_selectedEntries.picks();
         const int destIndex = MAX(0, m_hot.color);
-        const int palSize = currentPalette()->size();
+        const int palSize = m_adapter->size();
         const int newPalSize =
           (m_copy ? MAX(palSize + picks, destIndex + picks):
                     MAX(palSize,         destIndex + picks));
 
-        statusBar->setStatusText(
-          0, "%s to %d - New Palette Size %d",
-          (m_copy ? "Copy": "Move"),
-          destIndex, newPalSize);
+        m_adapter->showDragInfoInStatusBar(
+          statusBar, m_copy, destIndex, newPalSize);
       }
       else {
         statusBar->showDefaultText();
@@ -946,10 +1138,9 @@ void PaletteView::setStatusBar()
       if (m_hot.part == Hit::COLOR ||
           m_hot.part == Hit::POSSIBLE_COLOR ||
           m_hot.part == Hit::RESIZE_HANDLE) {
-        int newPalSize = MAX(1, m_hot.color);
-        statusBar->setStatusText(
-          0, "New Palette Size %d",
-          newPalSize);
+        const int newSize = MAX(1, m_hot.color);
+
+        m_adapter->showResizeInfoInStatusBar(statusBar, newSize);
       }
       else {
         statusBar->showDefaultText();
@@ -1003,36 +1194,6 @@ void PaletteView::setNewPalette(doc::Palette* oldPalette,
   manager()->invalidate();
 }
 
-void PaletteView::drawEntry(ui::Graphics* g,
-                            const int palIdx,
-                            const int offIdx,
-                            gfx::Rect& box,
-                            gfx::Color& negColor)
-{
-  doc::color_t palColor =
-    (palIdx < currentPalette()->size() ? currentPalette()->getEntry(palIdx):
-                                         rgba(0, 0, 0, 255));
-  app::Color appColor = app::Color::fromRgb(
-    rgba_getr(palColor),
-    rgba_getg(palColor),
-    rgba_getb(palColor),
-    rgba_geta(palColor));
-
-  if (m_withSeparator) {
-    auto theme = static_cast<SkinTheme*>(this->theme());
-    gfx::Color color = theme->colors.paletteEntriesSeparator();
-    g->fillRect(color, gfx::Rect(box).enlarge(childSpacing()));
-  }
-  draw_color(g, box, appColor, doc::ColorMode::RGB);
-
-  const gfx::Color gfxColor = gfx::rgba(
-    rgba_getr(palColor),
-    rgba_getg(palColor),
-    rgba_getb(palColor),
-    rgba_geta(palColor));
-  negColor = color_utils::blackandwhite_neg(gfxColor);
-}
-
 int PaletteView::boxSizePx() const
 {
   return m_boxsize*guiscale()
diff --git a/src/app/ui/palette_view.h b/src/app/ui/palette_view.h
index c20d2ae92..d64f2b47a 100644
--- a/src/app/ui/palette_view.h
+++ b/src/app/ui/palette_view.h
@@ -10,19 +10,23 @@
 #pragma once
 
 #include "app/color.h"
+#include "app/context_observer.h"
 #include "app/ui/color_source.h"
 #include "app/ui/marching_ants.h"
 #include "doc/palette_picks.h"
+#include "doc/tile.h"
 #include "obs/connection.h"
 #include "obs/signal.h"
 #include "ui/event.h"
 #include "ui/mouse_buttons.h"
 #include "ui/widget.h"
 
+#include <memory>
 #include <vector>
 
 namespace doc {
   class Palette;
+  class Tileset;
 }
 
 namespace app {
@@ -43,20 +47,32 @@ namespace app {
       const doc::Palette* fromPal, const doc::PalettePicks& from, const doc::PalettePicks& to) { }
     virtual app::Color onPaletteViewGetForegroundIndex() { return app::Color::fromMask(); }
     virtual app::Color onPaletteViewGetBackgroundIndex() { return app::Color::fromMask(); }
+    virtual void onPaletteViewClearTiles(const doc::PalettePicks& tiles) { }
   };
 
+  class AbstractPaletteViewAdapter;
+  class PaletteViewAdapter;
+
   class PaletteView : public ui::Widget
                     , public MarchingAnts
-                    , public IColorSource {
+                    , public IColorSource
+                    , public ContextObserver {
+    friend class PaletteViewAdapter;
   public:
     enum PaletteViewStyle {
       SelectOneColor,
-      FgBgColors
+      FgBgColors,
+      FgBgTiles,
     };
 
     PaletteView(bool editable, PaletteViewStyle style, PaletteViewDelegate* delegate, int boxsize);
+    ~PaletteView();
+
+    PaletteViewDelegate* delegate() { return m_delegate; }
 
     bool isEditable() const { return m_editable; }
+    bool isPalette() const { return m_style != FgBgTiles; }
+    bool isTiles() const { return m_style == FgBgTiles; }
 
     int getColumns() const { return m_columns; }
     void setColumns(int columns);
@@ -72,9 +88,14 @@ namespace app {
     int getSelectedEntriesCount() const;
     void setSelectedEntries(const doc::PalettePicks& entries);
 
+    doc::Tileset* tileset() const;
+
     // IColorSource
     app::Color getColorByPosition(const gfx::Point& pos) override;
 
+    // ContextObserver impl
+    void onActiveSiteChange(const Site& site) override;
+
     int getBoxSize() const;
     void setBoxSize(double boxsize);
 
@@ -143,11 +164,6 @@ namespace app {
     int findExactIndex(const app::Color& color) const;
     void setNewPalette(doc::Palette* oldPalette, doc::Palette* newPalette,
                        PaletteViewModification mod);
-    void drawEntry(ui::Graphics* g,
-                   const int palIdx,
-                   const int offIdx,
-                   gfx::Rect& box,
-                   gfx::Color& negColor);
     int boxSizePx() const;
     void updateBorderAndChildSpacing();
 
@@ -155,6 +171,7 @@ namespace app {
     bool m_editable;
     PaletteViewStyle m_style;
     PaletteViewDelegate* m_delegate;
+    std::unique_ptr<AbstractPaletteViewAdapter> m_adapter;
     int m_columns;
     double m_boxsize;
     int m_currentEntry;
diff --git a/src/app/util/autocrop.cpp b/src/app/util/autocrop.cpp
index 1d3d9f780..708a996f3 100644
--- a/src/app/util/autocrop.cpp
+++ b/src/app/util/autocrop.cpp
@@ -276,7 +276,7 @@ gfx::Rect get_trimmed_bounds(
     gfx::Rect frameBounds;
     doc::color_t refColor;
     if (get_best_refcolor_for_trimming(image, refColor) &&
-        doc::algorithm::shrink_bounds(image, frameBounds, refColor)) {
+        doc::algorithm::shrink_bounds(image, refColor, nullptr, frameBounds)) {
       bounds = bounds.createUnion(frameBounds);
     }
 
diff --git a/src/app/util/cel_ops.cpp b/src/app/util/cel_ops.cpp
new file mode 100644
index 000000000..f352d2dda
--- /dev/null
+++ b/src/app/util/cel_ops.cpp
@@ -0,0 +1,540 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2001-2018  David Capello
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/util/cel_ops.h"
+
+#include "app/cmd/add_tile.h"
+#include "app/cmd/clear_cel.h"
+#include "app/cmd/clear_mask.h"
+#include "app/cmd/copy_region.h"
+#include "app/cmd/replace_image.h"
+#include "app/cmd/set_cel_position.h"
+#include "app/cmd_sequence.h"
+#include "app/doc.h"
+#include "doc/algorithm/fill_selection.h"
+#include "doc/algorithm/resize_image.h"
+#include "doc/algorithm/shrink_bounds.h"
+#include "doc/cel.h"
+#include "doc/grid.h"
+#include "doc/image.h"
+#include "doc/layer.h"
+#include "doc/layer_tilemap.h"
+#include "doc/mask.h"
+#include "doc/palette.h"
+#include "doc/primitives.h"
+#include "doc/sprite.h"
+#include "doc/tileset.h"
+#include "doc/tileset_hash_table.h"
+#include "doc/tilesets.h"
+#include "gfx/region.h"
+#include "render/dithering.h"
+#include "render/ordered_dither.h"
+#include "render/quantization.h"
+#include "render/render.h"
+
+#include <cmath>
+#include <memory>
+
+#define OPS_TRACE(...)
+
+namespace app {
+
+using namespace doc;
+
+template<typename ImageTraits>
+static void mask_image_templ(Image* image, const Image* bitmap)
+{
+  LockImageBits<ImageTraits> bits1(image);
+  const LockImageBits<BitmapTraits> bits2(bitmap);
+  typename LockImageBits<ImageTraits>::iterator it1, end1;
+  LockImageBits<BitmapTraits>::const_iterator it2, end2;
+  for (it1 = bits1.begin(), end1 = bits1.end(),
+       it2 = bits2.begin(), end2 = bits2.end();
+       it1 != end1 && it2 != end2; ++it1, ++it2) {
+    if (!*it2)
+      *it1 = image->maskColor();
+  }
+  ASSERT(it1 == end1);
+  ASSERT(it2 == end2);
+}
+
+static void mask_image(Image* image, Image* bitmap)
+{
+  ASSERT(image->bounds() == bitmap->bounds());
+  switch (image->pixelFormat()) {
+    case IMAGE_RGB:       return mask_image_templ<RgbTraits>(image, bitmap);
+    case IMAGE_GRAYSCALE: return mask_image_templ<GrayscaleTraits>(image, bitmap);
+    case IMAGE_INDEXED:   return mask_image_templ<IndexedTraits>(image, bitmap);
+  }
+}
+
+Cel* create_cel_copy(CmdSequence* cmds,
+                     const Cel* srcCel,
+                     const Sprite* dstSprite,
+                     Layer* dstLayer,
+                     const frame_t dstFrame)
+{
+  const Image* srcImage = srcCel->image();
+  doc::PixelFormat dstPixelFormat =
+    (dstLayer->isTilemap() ? IMAGE_TILEMAP:
+                             dstSprite->pixelFormat());
+  gfx::Size dstSize(srcImage->width(),
+                    srcImage->height());
+
+  // From Tilemap -> Image
+  if (srcCel->layer()->isTilemap() && !dstLayer->isTilemap()) {
+    auto layerTilemap = static_cast<doc::LayerTilemap*>(srcCel->layer());
+    const auto& grid = layerTilemap->tileset()->grid();
+    dstSize = grid.tilemapSizeToCanvas(dstSize);
+  }
+  // From Image or Tilemap -> Tilemap
+  else if (dstLayer->isTilemap()) {
+    auto layerTilemap = static_cast<doc::LayerTilemap*>(dstLayer);
+    auto grid = layerTilemap->tileset()->grid();
+    if (srcCel->layer()->isTilemap())  // TODO check if this is correct
+      grid.origin(grid.origin() + srcCel->position());
+    const gfx::Rect tilemapBounds = grid.canvasToTile(srcCel->bounds());
+    dstSize = tilemapBounds.size();
+  }
+
+  // New cel
+  std::unique_ptr<Cel> dstCel(
+    new Cel(dstFrame, ImageRef(Image::create(dstPixelFormat, dstSize.w, dstSize.h))));
+
+  dstCel->setOpacity(srcCel->opacity());
+  dstCel->data()->setUserData(srcCel->data()->userData());
+
+  // Special case were we copy from a tilemap...
+  if (srcCel->layer()->isTilemap()) {
+    if (dstLayer->isTilemap()) {
+      // Tilemap -> Tilemap (with same tileset)
+      // Best case, copy a cel in the same layer (we have the same
+      // tileset available, so we just copy the tilemap as it is).
+      if (srcCel->layer() == dstLayer) {
+        dstCel->image()->copy(srcImage, gfx::Clip(0, 0, srcImage->bounds()));
+      }
+      // Tilemap -> Tilemap (with different tilesets)
+      else {
+        doc::ImageSpec spec = dstSprite->spec();
+        spec.setSize(srcCel->bounds().size());
+        doc::ImageRef tmpImage(doc::Image::create(spec));
+        render::Render().renderCel(
+          tmpImage.get(),
+          dstSprite,
+          srcImage,
+          srcCel->layer(),
+          dstSprite->palette(dstCel->frame()),
+          gfx::Rect(gfx::Point(0, 0), srcCel->bounds().size()),
+          gfx::Clip(0, 0, tmpImage->bounds()),
+          255, BlendMode::NORMAL);
+
+        doc::ImageRef tilemap = dstCel->imageRef();
+
+        draw_image_into_new_tilemap_cel(
+          cmds, static_cast<doc::LayerTilemap*>(dstLayer), dstCel.get(),
+          tmpImage.get(),
+          srcCel->bounds().origin(),
+          srcCel->bounds().origin(),
+          srcCel->bounds(),
+          tilemap);
+      }
+      dstCel->setPosition(srcCel->position());
+    }
+    // Tilemap -> Image (so we convert the tilemap to a regular image)
+    else {
+      render::Render().renderCel(
+        dstCel->image(),
+        dstSprite,
+        srcImage,
+        srcCel->layer(),
+        dstSprite->palette(dstCel->frame()),
+        gfx::Rect(gfx::Point(0, 0), srcCel->bounds().size()),
+        gfx::Clip(0, 0, dstCel->image()->bounds()),
+        255, BlendMode::NORMAL);
+
+      // Shrink image
+      if (dstLayer->isTransparent()) {
+        auto bg = dstCel->image()->maskColor();
+        gfx::Rect bounds;
+        if (algorithm::shrink_bounds(dstCel->image(), bg, dstLayer, bounds)) {
+          ImageRef trimmed(doc::crop_image(dstCel->image(), bounds, bg));
+          dstCel->data()->setImage(trimmed, dstLayer);
+          dstCel->setPosition(srcCel->position() + bounds.origin());
+          return dstCel.release();
+        }
+      }
+    }
+  }
+  // Image -> Tilemap (we'll need to generate new tilesets)
+  else if (dstLayer->isTilemap()) {
+    doc::ImageRef tilemap = dstCel->imageRef();
+    draw_image_into_new_tilemap_cel(
+      cmds, static_cast<doc::LayerTilemap*>(dstLayer), dstCel.get(),
+      srcImage,
+      gfx::Point(0, 0),
+      srcCel->bounds().origin(),
+      srcCel->bounds(),
+      tilemap);
+  }
+  else if ((dstSprite->pixelFormat() != srcImage->pixelFormat()) ||
+           // If both images are indexed but with different palette, we can
+           // convert the source cel to RGB first.
+           (dstSprite->pixelFormat() == IMAGE_INDEXED &&
+            srcImage->pixelFormat() == IMAGE_INDEXED &&
+            srcCel->sprite()->palette(srcCel->frame())->countDiff(
+              dstSprite->palette(dstFrame), nullptr, nullptr))) {
+    ImageRef tmpImage(Image::create(IMAGE_RGB, srcImage->width(), srcImage->height()));
+    tmpImage->clear(0);
+
+    render::convert_pixel_format(
+      srcImage,
+      tmpImage.get(),
+      IMAGE_RGB,
+      render::Dithering(),
+      srcCel->sprite()->rgbMap(srcCel->frame()),
+      srcCel->sprite()->palette(srcCel->frame()),
+      srcCel->layer()->isBackground(),
+      0);
+
+    render::convert_pixel_format(
+      tmpImage.get(),
+      dstCel->image(),
+      IMAGE_INDEXED,
+      render::Dithering(),
+      dstSprite->rgbMap(dstFrame),
+      dstSprite->palette(dstFrame),
+      srcCel->layer()->isBackground(),
+      dstSprite->transparentColor());
+  }
+  // Simple case, where we copy both images
+  else {
+    render::composite_image(
+      dstCel->image(),
+      srcImage,
+      srcCel->sprite()->palette(srcCel->frame()),
+      0, 0, 255, BlendMode::SRC);
+  }
+
+  // Resize a referece cel to a non-reference layer
+  if (srcCel->layer()->isReference() && !dstLayer->isReference()) {
+    gfx::RectF srcBounds = srcCel->boundsF();
+
+    std::unique_ptr<Cel> dstCel2(
+      new Cel(dstFrame,
+              ImageRef(Image::create(dstSprite->pixelFormat(),
+                                     std::ceil(srcBounds.w),
+                                     std::ceil(srcBounds.h)))));
+    algorithm::resize_image(
+      dstCel->image(), dstCel2->image(),
+      algorithm::RESIZE_METHOD_NEAREST_NEIGHBOR,
+      nullptr, nullptr, 0);
+
+    dstCel.reset(dstCel2.release());
+    dstCel->setPosition(gfx::Point(srcBounds.origin()));
+  }
+  // Copy original cel bounds
+  else if (!dstLayer->isTilemap()) {
+    if (srcCel->layer() &&
+        srcCel->layer()->isReference()) {
+      dstCel->setBoundsF(srcCel->boundsF());
+    }
+    else {
+      dstCel->setPosition(srcCel->position());
+    }
+  }
+
+  return dstCel.release();
+}
+
+void draw_image_into_new_tilemap_cel(
+  CmdSequence* cmds,
+  doc::LayerTilemap* dstLayer,
+  doc::Cel* dstCel,
+  const doc::Image* srcImage,
+  const gfx::Point& originOffset,
+  const gfx::Point& srcImagePos,
+  const gfx::Rect& canvasBounds,
+  doc::ImageRef& newTilemap)
+{
+  ASSERT(dstLayer->isTilemap());
+
+  doc::Tileset* tileset = dstLayer->tileset();
+  doc::Grid grid = tileset->grid();
+  grid.origin(grid.origin() + originOffset);
+
+  doc::TilesetHashTable hashImages; // TODO the hashImages should be inside the Tileset
+  {
+    // Add existent tiles in the hash table
+    int i = 0;
+    for (auto& image : *tileset)
+      hashImages[image] = i++;
+  }
+
+  gfx::Size tileSize = grid.tileSize();
+  const gfx::Rect tilemapBounds = grid.canvasToTile(canvasBounds);
+
+  if (!newTilemap) {
+    newTilemap.reset(doc::Image::create(IMAGE_TILEMAP,
+                                        tilemapBounds.w,
+                                        tilemapBounds.h));
+    newTilemap->clear(0); // <- This should not necessary
+  }
+  else {
+    ASSERT(tilemapBounds.w == newTilemap->width());
+    ASSERT(tilemapBounds.h == newTilemap->height());
+  }
+
+  for (const gfx::Point& tilePt : grid.tilesInCanvasRegion(gfx::Region(canvasBounds))) {
+    const gfx::Point tilePtInCanvas = grid.tileToCanvas(tilePt);
+    doc::ImageRef tileImage(
+      doc::crop_image(srcImage,
+                      tilePtInCanvas.x-srcImagePos.x,
+                      tilePtInCanvas.y-srcImagePos.y,
+                      tileSize.w, tileSize.h,
+                      srcImage->maskColor()));
+    if (grid.hasMask())
+      mask_image(tileImage.get(), grid.mask().get());
+
+    doc::tile_index tileIndex = 0;
+
+    auto it = hashImages.find(tileImage);
+    if (it != hashImages.end()) {
+      tileIndex = it->second; // TODO
+    }
+    else {
+      auto addTile = new cmd::AddTile(tileset, tileImage);
+      cmds->executeAndAdd(addTile);
+
+      tileIndex = addTile->tileIndex();
+      hashImages[tileImage] = tileIndex;
+    }
+
+    newTilemap->putPixel(
+      tilePt.x-tilemapBounds.x,
+      tilePt.y-tilemapBounds.y, doc::tile(tileIndex, 0));
+  }
+
+  static_cast<Doc*>(dstLayer->sprite()->document())
+    ->notifyTilesetChanged(tileset);
+
+  dstCel->data()->setImage(newTilemap, dstLayer);
+  dstCel->setPosition(grid.tileToCanvas(tilemapBounds.origin()));
+}
+
+void modify_tilemap_cel_region(
+  CmdSequence* cmds,
+  doc::Cel* cel,
+  const gfx::Region& region,
+  const TilesetMode tilesetMode,
+  const GetTileImageFunc& getTileImage)
+{
+  OPS_TRACE("modify_tilemap_cel_region %d %d %d %d\n",
+            region.bounds().x, region.bounds().y,
+            region.bounds().w, region.bounds().h);
+
+  if (region.isEmpty())
+    return;
+
+  ASSERT(cel->layer() && cel->layer()->isTilemap());
+  ASSERT(cel->image()->pixelFormat() == IMAGE_TILEMAP);
+
+  doc::LayerTilemap* tilemapLayer = static_cast<doc::LayerTilemap*>(cel->layer());
+
+  Doc* doc = static_cast<Doc*>(tilemapLayer->sprite()->document());
+  doc::Tileset* tileset = tilemapLayer->tileset();
+  doc::Grid grid = tileset->grid();
+  grid.origin(grid.origin() + cel->position());
+
+  const gfx::Size tileSize = grid.tileSize();
+  const gfx::Rect oldTilemapBounds(grid.canvasToTile(cel->position()),
+                                   cel->image()->bounds().size());
+  const gfx::Rect patchTilemapBounds = grid.canvasToTile(region.bounds());
+  const gfx::Rect newTilemapBounds = (oldTilemapBounds | patchTilemapBounds);
+
+  OPS_TRACE("modify_tilemap_cel_region:\n"
+            " - grid.origin       =%d %d\n"
+            " - cel.position      =%d %d\n"
+            " - oldTilemapBounds  =%d %d %d %d\n"
+            " - patchTilemapBounds=%d %d %d %d (region.bounds = %d %d %d %d)\n"
+            " - newTilemapBounds  =%d %d %d %d\n",
+            grid.origin().x, grid.origin().y,
+            cel->position().x, cel->position().y,
+            oldTilemapBounds.x, oldTilemapBounds.y, oldTilemapBounds.w, oldTilemapBounds.h,
+            patchTilemapBounds.x, patchTilemapBounds.y, patchTilemapBounds.w, patchTilemapBounds.h,
+            region.bounds().x, region.bounds().y, region.bounds().w, region.bounds().h,
+            newTilemapBounds.x, newTilemapBounds.y, newTilemapBounds.w, newTilemapBounds.h);
+
+  // Autogenerate tiles
+  if (tilesetMode == TilesetMode::GenerateAllTiles) {
+    doc::TilesetHashTable hashImages; // TODO the hashImages should be inside the Tileset
+    {
+      // Add existent tiles in the hash table
+      int i = 0;
+      for (auto& image : *tileset)
+        hashImages[image] = i++;
+    }
+
+    // TODO create a smaller image
+    doc::ImageRef newTilemap(
+      doc::Image::create(IMAGE_TILEMAP,
+                         newTilemapBounds.w,
+                         newTilemapBounds.h));
+
+    newTilemap->clear(0);   // TODO find the tile with empty content?
+    newTilemap->copy(
+      cel->image(),
+      gfx::Clip(oldTilemapBounds.x-newTilemapBounds.x,
+                oldTilemapBounds.y-newTilemapBounds.y, 0, 0,
+                oldTilemapBounds.w, oldTilemapBounds.h));
+
+    gfx::Region tilePtsRgn;
+
+    // This region includes the modified region by the user + the
+    // extra region added as we've incremented the tilemap size
+    // (newTilemapBounds).
+    gfx::Region regionToPatch(grid.tileToCanvas(newTilemapBounds));
+    regionToPatch -= gfx::Region(grid.tileToCanvas(oldTilemapBounds));
+    regionToPatch |= region;
+
+    for (const gfx::Point& tilePt : grid.tilesInCanvasRegion(regionToPatch)) {
+      const int u = tilePt.x-newTilemapBounds.x;
+      const int v = tilePt.y-newTilemapBounds.y;
+      OPS_TRACE(" - modify tile xy=%d %d uv=%d %d\n", tilePt.x, tilePt.y, u, v);
+      if (!newTilemap->bounds().contains(u, v))
+        continue;
+
+      const doc::tile_t t = newTilemap->getPixel(u, v);
+      const doc::tile_index ti = doc::tile_geti(t);
+      const doc::ImageRef existenTileImage = tileset->get(ti);
+
+      const gfx::Rect tileInCanvasRc(grid.tileToCanvas(tilePt), tileSize);
+      ImageRef tileImage(getTileImage(existenTileImage, tileInCanvasRc));
+      if (grid.hasMask())
+        mask_image(tileImage.get(), grid.mask().get());
+
+      tile_index tileIndex = 0;
+
+      auto it = hashImages.find(tileImage);
+      if (it != hashImages.end()) {
+        tileIndex = it->second; // TODO
+      }
+      else {
+        auto addTile = new cmd::AddTile(tileset, tileImage);
+        cmds->executeAndAdd(addTile);
+
+        tileIndex = addTile->tileIndex();
+        hashImages[tileImage] = tileIndex;
+      }
+
+      const doc::tile_t tile = doc::tile(tileIndex, 0);
+      if (t != tile) {
+        newTilemap->putPixel(u, v, tile);
+        tilePtsRgn |= gfx::Region(gfx::Rect(u, v, 1, 1));
+      }
+    }
+
+    doc->notifyTilesetChanged(tileset);
+
+    if (newTilemap->width() != cel->image()->width() ||
+        newTilemap->height() != cel->image()->height()) {
+      gfx::Point newPos = grid.tileToCanvas(newTilemapBounds.origin());
+      if (cel->position() != newPos) {
+        cmds->executeAndAdd(
+          new cmd::SetCelPosition(cel, newPos.x, newPos.y));
+      }
+      cmds->executeAndAdd(
+        new cmd::ReplaceImage(cel->sprite(), cel->imageRef(), newTilemap));
+    }
+    else {
+      cmds->executeAndAdd(
+        new cmd::CopyRegion(
+          cel->image(),
+          newTilemap.get(),
+          tilePtsRgn,
+          gfx::Point(0, 0)));
+    }
+  }
+  // Modify active set of tiles manually / don't auto-generate new tiles
+  else if (tilesetMode == TilesetMode::ModifyExistent) {
+    for (const gfx::Point& tilePt : grid.tilesInCanvasRegion(region)) {
+      // Ignore modifications outside the tilemap
+      if (!cel->image()->bounds().contains(tilePt.x, tilePt.y))
+        continue;
+
+      const doc::tile_t t = cel->image()->getPixel(tilePt.x, tilePt.y);
+      const doc::tile_index ti = doc::tile_geti(t);
+      const doc::ImageRef existenTileImage = tileset->get(ti);
+
+      const gfx::Rect tileInCanvasRc(grid.tileToCanvas(tilePt), tileSize);
+      ImageRef tileImage(getTileImage(existenTileImage, tileInCanvasRc));
+      if (grid.hasMask())
+        mask_image(tileImage.get(), grid.mask().get());
+
+      gfx::Region tileRgn(tileInCanvasRc);
+      tileRgn.createIntersection(tileRgn, region);
+      tileRgn.offset(-tileInCanvasRc.origin());
+
+      ImageRef tileOrigImage = tileset->get(ti);
+
+      cmds->executeAndAdd(
+        new cmd::CopyRegion(
+          tileOrigImage.get(),
+          tileImage.get(),
+          tileRgn,
+          gfx::Point(0, 0)));
+    }
+
+    doc->notifyTilesetChanged(tileset);
+  }
+}
+
+void clear_mask_from_cel(CmdSequence* cmds,
+                         doc::Cel* cel,
+                         const TilesetMode tilesetMode)
+{
+  ASSERT(cmds);
+  ASSERT(cel);
+  ASSERT(cel->layer());
+
+  if (cel->layer()->isTilemap()) {
+    Doc* doc = static_cast<Doc*>(cel->document());
+
+    // Simple case (there is no visible selection, so we remove the
+    // whole cel)
+    if (!doc->isMaskVisible()) {
+      cmds->executeAndAdd(new cmd::ClearCel(cel));
+      return;
+    }
+
+    color_t bgcolor = doc->bgColor(cel->layer());
+    doc::Mask* mask = doc->mask();
+
+    modify_tilemap_cel_region(
+      cmds, cel,
+      gfx::Region(doc->mask()->bounds()),
+      tilesetMode,
+      [bgcolor, mask](const doc::ImageRef& origTile,
+                const gfx::Rect& tileBoundsInCanvas) -> doc::ImageRef {
+        doc::ImageRef modified(doc::Image::createCopy(origTile.get()));
+        doc::algorithm::fill_selection(
+          modified.get(),
+          mask->bounds().origin() - tileBoundsInCanvas.origin(),
+          mask,
+          bgcolor);
+        return modified;
+      });
+  }
+  else {
+    cmds->executeAndAdd(new cmd::ClearMask(cel));
+  }
+}
+
+} // namespace app
diff --git a/src/app/util/cel_ops.h b/src/app/util/cel_ops.h
new file mode 100644
index 000000000..9c05f0057
--- /dev/null
+++ b/src/app/util/cel_ops.h
@@ -0,0 +1,67 @@
+// Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
+// Copyright (C) 2001-2016  David Capello
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifndef APP_UTIL_CEL_OPS_H_INCLUDED
+#define APP_UTIL_CEL_OPS_H_INCLUDED
+#pragma once
+
+#include "app/tileset_mode.h"
+#include "doc/frame.h"
+#include "doc/image_ref.h"
+#include "gfx/point.h"
+#include "gfx/region.h"
+
+#include <functional>
+
+namespace doc {
+  class Cel;
+  class Layer;
+  class LayerTilemap;
+  class Sprite;
+}
+
+namespace app {
+  class CmdSequence;
+
+  typedef std::function<doc::ImageRef(const doc::ImageRef& origTile,
+                                      const gfx::Rect& tileBoundsInCanvas)> GetTileImageFunc;
+
+  // The "cmds" is used in case that new tiles must be added in the
+  // dstLayer tilesets.
+  doc::Cel* create_cel_copy(
+    CmdSequence* cmds,
+    const doc::Cel* srcCel,
+    const doc::Sprite* dstSprite,
+    doc::Layer* dstLayer,
+    const doc::frame_t dstFrame);
+
+  // Draws an image creating new tiles.
+  void draw_image_into_new_tilemap_cel(
+    CmdSequence* cmds,
+    doc::LayerTilemap* dstLayer,
+    doc::Cel* dstCel,
+    const doc::Image* srcImage,
+    const gfx::Point& originOffset,
+    const gfx::Point& srcImagePos,
+    const gfx::Rect& canvasBounds,
+    doc::ImageRef& newTilemap);
+
+  void modify_tilemap_cel_region(
+    CmdSequence* cmds,
+    doc::Cel* cel,
+    const gfx::Region& region,
+    const TilesetMode tilesetMode,
+    const GetTileImageFunc& getTileImage);
+
+  void clear_mask_from_cel(
+    CmdSequence* cmds,
+    doc::Cel* cel,
+    const TilesetMode tilesetMode);
+
+} // namespace app
+
+#endif
diff --git a/src/app/util/clipboard.cpp b/src/app/util/clipboard.cpp
index cc64b75f9..21aeccd52 100644
--- a/src/app/util/clipboard.cpp
+++ b/src/app/util/clipboard.cpp
@@ -30,6 +30,7 @@
 #include "app/ui/skin/skin_theme.h"
 #include "app/ui/timeline/timeline.h"
 #include "app/ui_context.h"
+#include "app/util/cel_ops.h"
 #include "app/util/clipboard.h"
 #include "app/util/clipboard_native.h"
 #include "app/util/new_image_from_mask.h"
@@ -248,12 +249,14 @@ void clear_mask_from_cels(Tx& tx,
   for (Cel* cel : cels) {
     ObjectId celId = cel->id();
 
-    tx(new cmd::ClearMask(cel));
+    clear_mask_from_cel(
+      tx, cel, ColorBar::instance()->tilesetMode());
 
     // Get cel again just in case the cmd::ClearMask() called cmd::ClearCel()
     cel = doc::get<Cel>(celId);
     if (cel &&
-        cel->layer()->isTransparent()) {
+        cel->layer()->isTransparent() &&
+        !cel->layer()->isTilemap()) {
       tx(new cmd::TrimCel(cel));
     }
   }
@@ -278,6 +281,7 @@ void cut(ContextWriter& writer)
     console.printf("Can't copying an image portion from the current layer\n");
   }
   else {
+    // TODO This code is similar to DocView::onClear()
     {
       Tx tx(writer.context(), "Cut");
       Site site = writer.context()->activeSite();
diff --git a/src/app/util/create_cel_copy.cpp b/src/app/util/create_cel_copy.cpp
deleted file mode 100644
index 324d4f91b..000000000
--- a/src/app/util/create_cel_copy.cpp
+++ /dev/null
@@ -1,116 +0,0 @@
-// Aseprite
-// Copyright (C) 2019  Igara Studio S.A.
-// Copyright (C) 2001-2018  David Capello
-//
-// This program is distributed under the terms of
-// the End-User License Agreement for Aseprite.
-
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
-
-#include "doc/algorithm/resize_image.h"
-#include "doc/cel.h"
-#include "doc/image.h"
-#include "doc/layer.h"
-#include "doc/palette.h"
-#include "doc/primitives.h"
-#include "doc/sprite.h"
-#include "render/dithering.h"
-#include "render/ordered_dither.h"
-#include "render/quantization.h"
-#include "render/render.h"
-
-#include <cmath>
-#include <memory>
-
-namespace app {
-
-using namespace doc;
-
-Cel* create_cel_copy(const Cel* srcCel,
-                     const Sprite* dstSprite,
-                     const Layer* dstLayer,
-                     const frame_t dstFrame)
-{
-  const Image* celImage = srcCel->image();
-
-  std::unique_ptr<Cel> dstCel(
-    new Cel(dstFrame,
-            ImageRef(Image::create(dstSprite->pixelFormat(),
-                                   celImage->width(),
-                                   celImage->height()))));
-
-  if ((dstSprite->pixelFormat() != celImage->pixelFormat()) ||
-      // If both images are indexed but with different palette, we can
-      // convert the source cel to RGB first.
-      (dstSprite->pixelFormat() == IMAGE_INDEXED &&
-       celImage->pixelFormat() == IMAGE_INDEXED &&
-       srcCel->sprite()->palette(srcCel->frame())->countDiff(
-         dstSprite->palette(dstFrame), nullptr, nullptr))) {
-    ImageRef tmpImage(Image::create(IMAGE_RGB, celImage->width(), celImage->height()));
-    tmpImage->clear(0);
-
-    render::convert_pixel_format(
-      celImage,
-      tmpImage.get(),
-      IMAGE_RGB,
-      render::Dithering(),
-      srcCel->sprite()->rgbMap(srcCel->frame()),
-      srcCel->sprite()->palette(srcCel->frame()),
-      srcCel->layer()->isBackground(),
-      0);
-
-    render::convert_pixel_format(
-      tmpImage.get(),
-      dstCel->image(),
-      IMAGE_INDEXED,
-      render::Dithering(),
-      dstSprite->rgbMap(dstFrame),
-      dstSprite->palette(dstFrame),
-      srcCel->layer()->isBackground(),
-      dstSprite->transparentColor());
-  }
-  else {
-    render::composite_image(
-      dstCel->image(),
-      celImage,
-      srcCel->sprite()->palette(srcCel->frame()),
-      0, 0, 255, BlendMode::SRC);
-  }
-
-  // Resize a referecen cel to a non-reference layer
-  if (srcCel->layer()->isReference() && !dstLayer->isReference()) {
-    gfx::RectF srcBounds = srcCel->boundsF();
-
-    std::unique_ptr<Cel> dstCel2(
-      new Cel(dstFrame,
-              ImageRef(Image::create(dstSprite->pixelFormat(),
-                                     std::ceil(srcBounds.w),
-                                     std::ceil(srcBounds.h)))));
-    algorithm::resize_image(
-      dstCel->image(), dstCel2->image(),
-      algorithm::RESIZE_METHOD_NEAREST_NEIGHBOR,
-      nullptr, nullptr, 0);
-
-    dstCel.reset(dstCel2.release());
-    dstCel->setPosition(gfx::Point(srcBounds.origin()));
-  }
-  // Copy original cel bounds
-  else {
-    if (srcCel->layer() &&
-        srcCel->layer()->isReference()) {
-      dstCel->setBoundsF(srcCel->boundsF());
-    }
-    else {
-      dstCel->setPosition(srcCel->position());
-    }
-  }
-
-  dstCel->setOpacity(srcCel->opacity());
-  dstCel->data()->setUserData(srcCel->data()->userData());
-
-  return dstCel.release();
-}
-
-} // namespace app
diff --git a/src/app/util/create_cel_copy.h b/src/app/util/create_cel_copy.h
deleted file mode 100644
index 4ab16ba52..000000000
--- a/src/app/util/create_cel_copy.h
+++ /dev/null
@@ -1,27 +0,0 @@
-// Aseprite
-// Copyright (C) 2001-2016  David Capello
-//
-// This program is distributed under the terms of
-// the End-User License Agreement for Aseprite.
-
-#ifndef APP_UTIL_CREATE_CEL_COPY_H_INCLUDED
-#define APP_UTIL_CREATE_CEL_COPY_H_INCLUDED
-#pragma once
-
-#include "doc/frame.h"
-
-namespace doc {
-  class Cel;
-  class Sprite;
-}
-
-namespace app {
-
-  Cel* create_cel_copy(const Cel* srcCel,
-                       const Sprite* dstSprite,
-                       const Layer* dstLayer,
-                       const frame_t dstFrame);
-
-} // namespace app
-
-#endif
diff --git a/src/app/util/expand_cel_canvas.cpp b/src/app/util/expand_cel_canvas.cpp
index 8ea1f77ae..f884ffdd5 100644
--- a/src/app/util/expand_cel_canvas.cpp
+++ b/src/app/util/expand_cel_canvas.cpp
@@ -13,21 +13,28 @@
 
 #include "app/app.h"
 #include "app/cmd/add_cel.h"
-#include "app/cmd/clear_cel.h"
+#include "app/cmd/copy_rect.h"
 #include "app/cmd/copy_region.h"
 #include "app/cmd/patch_cel.h"
+#include "app/cmd_sequence.h"
 #include "app/context.h"
 #include "app/doc.h"
 #include "app/site.h"
-#include "app/transaction.h"
+#include "app/util/cel_ops.h"
 #include "app/util/range_utils.h"
 #include "doc/algorithm/shrink_bounds.h"
 #include "doc/cel.h"
 #include "doc/image.h"
+#include "doc/image_impl.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/primitives.h"
 #include "doc/sprite.h"
+#include "doc/tileset.h"
+#include "doc/tileset_hash_table.h"
+#include "doc/tilesets.h"
 #include "gfx/rect_io.h"
+#include "render/render.h"
 
 #define EXP_TRACE(...) // TRACEARGS
 
@@ -61,8 +68,11 @@ static void create_buffers()
 namespace app {
 
 ExpandCelCanvas::ExpandCelCanvas(
-  Site site, Layer* layer,
-  TiledMode tiledMode, Transaction& transaction, Flags flags)
+  Site site,
+  Layer* layer,
+  const TiledMode tiledMode,
+  CmdSequence* cmds,
+  const Flags flags)
   : m_document(site.document())
   , m_sprite(site.sprite())
   , m_layer(layer)
@@ -75,9 +85,14 @@ ExpandCelCanvas::ExpandCelCanvas(
   , m_dstImage(NULL)
   , m_closed(false)
   , m_committed(false)
-  , m_transaction(transaction)
-  , m_canCompareSrcVsDst((m_flags & NeedsSource) == NeedsSource)
+  , m_cmds(cmds)
+  , m_tilesetMode(site.tilesetMode())
 {
+  if (m_layer && m_layer->isTilemap()) {
+    m_flags = Flags(m_flags | NeedsSource);
+  }
+  m_canCompareSrcVsDst = ((m_flags & NeedsSource) == NeedsSource);
+
   ASSERT(!singleton);
   singleton = this;
 
@@ -98,11 +113,7 @@ ExpandCelCanvas::ExpandCelCanvas(
   m_origCelPos = m_cel->position();
 
   // Region to draw
-  gfx::Rect celBounds(
-    m_cel->x(),
-    m_cel->y(),
-    m_celImage ? m_celImage->width(): m_sprite->width(),
-    m_celImage ? m_celImage->height(): m_sprite->height());
+  gfx::Rect celBounds = (m_celCreated ? m_sprite->bounds(): m_cel->bounds());
 
   gfx::Rect spriteBounds(0, 0,
     m_sprite->width(),
@@ -122,11 +133,18 @@ ExpandCelCanvas::ExpandCelCanvas(
 
   if (m_celCreated) {
     getDestCanvas();
-    m_cel->data()->setImage(m_dstImage);
+    m_cel->data()->setImage(m_dstImage, m_layer);
 
     if (m_layer && m_layer->isImage())
       static_cast<LayerImage*>(m_layer)->addCel(m_cel);
   }
+  // If we are in a tilemap, we use m_dstImage to draw pixels (instead
+  // of the tilemap image).
+  else if (m_layer->isTilemap()) {
+    // Calling "getDestCanvas()" we create the m_dstImage
+    getDestCanvas();
+    m_cel->data()->setImage(m_dstImage, m_layer);
+  }
 }
 
 ExpandCelCanvas::~ExpandCelCanvas()
@@ -166,21 +184,34 @@ void ExpandCelCanvas::commit()
     // don't have a m_celImage)
     validateDestCanvas(gfx::Region(m_bounds));
 
-    // We can temporary remove the cel.
     if (m_layer->isImage()) {
+      // We can temporary remove the cel.
       static_cast<LayerImage*>(m_layer)->removeCel(m_cel);
 
-      // Add a copy of m_dstImage in the sprite's image stock
       gfx::Rect trimBounds = getTrimDstImageBounds();
       if (!trimBounds.isEmpty()) {
-        ImageRef newImage(trimDstImage(trimBounds));
-        ASSERT(newImage);
+        // Convert the image to tiles
+        if (m_layer->isTilemap()) {
+          doc::ImageRef newTilemap;
+          draw_image_into_new_tilemap_cel(
+            m_cmds, static_cast<doc::LayerTilemap*>(m_layer), m_cel,
+            // Draw the dst image in the tilemap
+            m_dstImage.get(),
+            m_origCelPos,
+            gfx::Point(0, 0), // m_dstImage->bounds(),
+            trimBounds,
+            newTilemap);
+        }
+        else {
+          ImageRef newImage(trimDstImage(trimBounds));
+          ASSERT(newImage);
 
-        m_cel->data()->setImage(newImage);
-        m_cel->setPosition(m_cel->position() + trimBounds.origin());
+          m_cel->data()->setImage(newImage, m_layer);
+          m_cel->setPosition(m_cel->position() + trimBounds.origin());
+        }
 
-        // And finally we add the cel again in the layer.
-        m_transaction.execute(new cmd::AddCel(m_layer, m_cel));
+        // And add the cel again in the layer.
+        m_cmds->executeAndAdd(new cmd::AddCel(m_layer, m_cel));
       }
     }
     // We are selecting inside a layer group...
@@ -194,7 +225,14 @@ void ExpandCelCanvas::commit()
     // Restore cel position to its original position
     m_cel->setPosition(m_origCelPos);
 
-    ASSERT(m_cel->image() == m_celImage.get());
+#ifdef _DEBUG
+    if (m_layer->isTilemap()) {
+      ASSERT(m_cel->image() != m_celImage.get());
+    }
+    else {
+      ASSERT(m_cel->image() == m_celImage.get());
+    }
+#endif
 
     gfx::Region* regionToPatch = &m_validDstRegion;
     gfx::Region reduced;
@@ -214,11 +252,40 @@ void ExpandCelCanvas::commit()
 
     EXP_TRACE(" - regionToPatch", regionToPatch->bounds());
 
+    // Convert the image to tiles again
+    if (m_layer->isTilemap()) {
+      ASSERT(m_celImage.get() != m_cel->image());
+      ASSERT(m_celImage->pixelFormat() == IMAGE_TILEMAP);
+
+      // Validate the whole m_dstImage (invalid areas are cleared, as we
+      // don't have a m_celImage)
+      validateDestCanvas(gfx::Region(m_bounds));
+
+      // Restore the original m_celImage, because the cel contained
+      // the m_dstImage temporally for drawing purposes. No undo
+      // information is required at this moment.
+      m_cel->data()->setImage(m_celImage, m_layer);
+
+      // Put the region in absolute sprite canvas coordinates (instead
+      // of relative to the m_cel).
+      regionToPatch->offset(m_bounds.origin());
+
+      modify_tilemap_cel_region(
+        m_cmds, m_cel,
+        *regionToPatch,
+        m_tilesetMode,
+        [this](const doc::ImageRef& origTile,
+               const gfx::Rect& tileBoundsInCanvas) -> doc::ImageRef {
+          return trimDstImage(tileBoundsInCanvas);
+        });
+    }
     // Check that the region to copy or patch is not empty before we
     // create the new cmd
-    if (!regionToPatch->isEmpty()) {
+    else if (!regionToPatch->isEmpty()) {
+      ASSERT(m_celImage.get() == m_cel->image());
+
       if (m_layer->isBackground()) {
-        m_transaction.execute(
+        m_cmds->executeAndAdd(
           new cmd::CopyRegion(
             m_cel->image(),
             m_dstImage.get(),
@@ -226,7 +293,7 @@ void ExpandCelCanvas::commit()
             m_bounds.origin()));
       }
       else {
-        m_transaction.execute(
+        m_cmds->executeAndAdd(
           new cmd::PatchCel(
             m_cel,
             m_dstImage.get(),
@@ -257,6 +324,13 @@ void ExpandCelCanvas::rollback()
     delete m_cel;
     m_celImage.reset();
   }
+  // Restore the original tilemap
+  else if (m_layer->isTilemap()) {
+    ASSERT(m_cel->image()->pixelFormat() == m_sprite->pixelFormat());
+    ASSERT(m_celImage->pixelFormat() == IMAGE_TILEMAP);
+    m_cel->data()->setImage(m_celImage,
+                            m_cel->layer());
+  }
 
   m_closed = true;
 }
@@ -298,18 +372,41 @@ void ExpandCelCanvas::validateSourceCanvas(const gfx::Region& rgn)
 
   if (m_celImage) {
     gfx::Region rgnToClear;
-    rgnToClear.createSubtraction(rgnToValidate,
+    rgnToClear.createSubtraction(
+      rgnToValidate,
       gfx::Region(m_celImage->bounds()
-        .offset(m_origCelPos)
-        .offset(-m_bounds.origin())));
+                  .offset(m_origCelPos)
+                  .offset(-m_bounds.origin())));
     for (const auto& rc : rgnToClear)
       fill_rect(m_srcImage.get(), rc, m_srcImage->maskColor());
 
-    for (const auto& rc : rgnToValidate)
-      m_srcImage->copy(m_celImage.get(),
-        gfx::Clip(rc.x, rc.y,
-          rc.x+m_bounds.x-m_origCelPos.x,
-          rc.y+m_bounds.y-m_origCelPos.y, rc.w, rc.h));
+    if (m_celImage->pixelFormat() == IMAGE_TILEMAP) {
+      // For tilemaps, we can use the Render class to render visible
+      // tiles in the rgnToValidate of this cel.
+      render::Render subRender;
+      for (const auto& rc : rgnToValidate) {
+        subRender.renderCel(
+          m_srcImage.get(),
+          m_sprite,
+          m_celImage.get(),
+          m_layer,
+          m_sprite->palette(m_frame),
+          gfx::RectF(0, 0, m_bounds.w, m_bounds.h),
+          gfx::Clip(rc.x, rc.y,
+                    rc.x+m_bounds.x-m_origCelPos.x,
+                    rc.y+m_bounds.y-m_origCelPos.y, rc.w, rc.h),
+          255, BlendMode::NORMAL);
+      }
+    }
+    else {
+      // We can copy the cel image directly
+      for (const auto& rc : rgnToValidate)
+        m_srcImage->copy(
+          m_celImage.get(),
+          gfx::Clip(rc.x, rc.y,
+                    rc.x+m_bounds.x-m_origCelPos.x,
+                    rc.y+m_bounds.y-m_origCelPos.y, rc.w, rc.h));
+    }
   }
   else {
     for (const auto& rc : rgnToValidate)
@@ -332,18 +429,19 @@ void ExpandCelCanvas::validateDestCanvas(const gfx::Region& rgn)
     src_y = m_bounds.y;
   }
   else {
-    src = m_celImage.get();
+    src = m_cel->image();
     src_x = m_origCelPos.x;
     src_y = m_origCelPos.y;
   }
 
-  getDestCanvas();
+  getDestCanvas();              // Create m_dstImage
 
   gfx::Region rgnToValidate(rgn);
   rgnToValidate.offset(-m_bounds.origin());
   rgnToValidate.createSubtraction(rgnToValidate, m_validDstRegion);
   rgnToValidate.createIntersection(rgnToValidate, gfx::Region(m_dstImage->bounds()));
 
+  // ASSERT(src);                  // TODO is it always true?
   if (src) {
     gfx::Region rgnToClear;
     rgnToClear.createSubtraction(rgnToValidate,
@@ -406,8 +504,8 @@ gfx::Rect ExpandCelCanvas::getTrimDstImageBounds() const
     return m_dstImage->bounds();
   else {
     gfx::Rect bounds;
-    algorithm::shrink_bounds(m_dstImage.get(), bounds,
-                             m_dstImage->maskColor());
+    algorithm::shrink_bounds(m_dstImage.get(),
+                             m_dstImage->maskColor(), nullptr, bounds);
     return bounds;
   }
 }
@@ -416,7 +514,8 @@ ImageRef ExpandCelCanvas::trimDstImage(const gfx::Rect& bounds) const
 {
   return ImageRef(
     crop_image(m_dstImage.get(),
-               bounds.x, bounds.y,
+               bounds.x-m_bounds.x,
+               bounds.y-m_bounds.y,
                bounds.w, bounds.h,
                m_dstImage->maskColor()));
 }
diff --git a/src/app/util/expand_cel_canvas.h b/src/app/util/expand_cel_canvas.h
index 811e2fb0e..c88e3192b 100644
--- a/src/app/util/expand_cel_canvas.h
+++ b/src/app/util/expand_cel_canvas.h
@@ -1,4 +1,5 @@
 // Aseprite
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -8,6 +9,7 @@
 #define APP_UTIL_EXPAND_CEL_CANVAS_H_INCLUDED
 #pragma once
 
+#include "app/tileset_mode.h"
 #include "doc/frame.h"
 #include "doc/image_ref.h"
 #include "filters/tiled_mode.h"
@@ -24,9 +26,9 @@ namespace doc {
 }
 
 namespace app {
+  class CmdSequence;
   class Doc;
   class Site;
-  class Transaction;
 
   using namespace filters;
   using namespace doc;
@@ -46,7 +48,9 @@ namespace app {
     };
 
     ExpandCelCanvas(Site site, Layer* layer,
-      TiledMode tiledMode, Transaction& undo, Flags flags);
+                    const TiledMode tiledMode,
+                    CmdSequence* cmds,
+                    const Flags flags);
     ~ExpandCelCanvas();
 
     // Commit changes made in getDestCanvas() in the cel's image. Adds
@@ -87,7 +91,7 @@ namespace app {
     ImageRef m_dstImage;
     bool m_closed;
     bool m_committed;
-    Transaction& m_transaction;
+    CmdSequence* m_cmds;
     gfx::Region m_validSrcRegion;
     gfx::Region m_validDstRegion;
 
@@ -95,6 +99,8 @@ namespace app {
     // cel. This is false when dst is copied to the src, so we cannot
     // reduce the patched region because both images will be the same.
     bool m_canCompareSrcVsDst;
+
+    TilesetMode m_tilesetMode;
   };
 
 } // namespace app
diff --git a/src/app/util/new_image_from_mask.cpp b/src/app/util/new_image_from_mask.cpp
index 3f58ec5d5..8c2ed4a2b 100644
--- a/src/app/util/new_image_from_mask.cpp
+++ b/src/app/util/new_image_from_mask.cpp
@@ -14,6 +14,7 @@
 #include "app/doc.h"
 #include "app/site.h"
 #include "doc/image_impl.h"
+#include "doc/layer.h"
 #include "doc/mask.h"
 #include "doc/primitives.h"
 #include "render/render.h"
@@ -53,7 +54,7 @@ doc::Image* new_image_from_mask(const Site& site,
 
   const Image* src = nullptr;
   int x = 0, y = 0;
-  if (merged) {
+  if (merged || site.layer()->isTilemap()) {
     render::Render render;
     render.setNewBlend(newBlend);
     render.renderSprite(dst.get(), srcSprite, site.frame(),
diff --git a/src/dio/LICENSE.txt b/src/dio/LICENSE.txt
index a3236b421..06faf6309 100644
--- a/src/dio/LICENSE.txt
+++ b/src/dio/LICENSE.txt
@@ -1,4 +1,4 @@
-Copyright (c) 2018 Igara Studio S.A.
+Copyright (c) 2018-2019 Igara Studio S.A.
 Copyright (c) 2016-2018 David Capello
 
 Permission is hereby granted, free of charge, to any person obtaining
diff --git a/src/dio/aseprite_common.h b/src/dio/aseprite_common.h
index a404fcdcf..31df25ef3 100644
--- a/src/dio/aseprite_common.h
+++ b/src/dio/aseprite_common.h
@@ -31,10 +31,12 @@
 
 #define ASE_FILE_LAYER_IMAGE                0
 #define ASE_FILE_LAYER_GROUP                1
+#define ASE_FILE_LAYER_TILEMAP              2
 
 #define ASE_FILE_RAW_CEL                    0
 #define ASE_FILE_LINK_CEL                   1
 #define ASE_FILE_COMPRESSED_CEL             2
+#define ASE_FILE_COMPRESSED_TILEMAP         3
 
 #define ASE_FILE_NO_COLOR_PROFILE           0
 #define ASE_FILE_SRGB_COLOR_PROFILE         1
diff --git a/src/dio/aseprite_decoder.cpp b/src/dio/aseprite_decoder.cpp
index fceaa0a60..2e7a8c095 100644
--- a/src/dio/aseprite_decoder.cpp
+++ b/src/dio/aseprite_decoder.cpp
@@ -201,8 +201,7 @@ bool AsepriteDecoder::decode()
           }
 
           case ASE_FILE_CHUNK_TILESET: {
-            delegate()->error(
-              "Warning: The given file contains a tileset.\nThis version of Aseprite doesn't support tilemap layers.\n");
+            readTilesetChunk(sprite.get(), &header);
             break;
           }
 
@@ -439,6 +438,12 @@ doc::Layer* AsepriteDecoder::readLayerChunk(AsepriteHeader* header,
     case ASE_FILE_LAYER_GROUP:
       layer = new doc::LayerGroup(sprite);
       break;
+
+    case ASE_FILE_LAYER_TILEMAP: {
+      doc::tileset_index tsi = read32();
+      layer = new doc::LayerTilemap(sprite, tsi);
+      break;
+    }
   }
 
   if (layer) {
@@ -481,11 +486,13 @@ doc::Layer* AsepriteDecoder::readLayerChunk(AsepriteHeader* header,
 // Raw Image
 //////////////////////////////////////////////////////////////////////
 
+namespace {
+
 template<typename ImageTraits>
 void read_raw_image(FileInterface* f,
                     DecodeDelegate* delegate,
                     doc::Image* image,
-                    AsepriteHeader* header)
+                    const AsepriteHeader* header)
 {
   PixelIO<ImageTraits> pixel_io;
   int x, y;
@@ -505,11 +512,11 @@ void read_raw_image(FileInterface* f,
 //////////////////////////////////////////////////////////////////////
 
 template<typename ImageTraits>
-void read_compressed_image(FileInterface* f,
-                           DecodeDelegate* delegate,
-                           doc::Image* image,
-                           size_t chunk_end,
-                           AsepriteHeader* header)
+void read_compressed_image_templ(FileInterface* f,
+                                 DecodeDelegate* delegate,
+                                 doc::Image* image,
+                                 const AsepriteHeader* header,
+                                 const size_t chunk_end)
 {
   PixelIO<ImageTraits> pixel_io;
   z_stream zstream;
@@ -538,8 +545,9 @@ void read_compressed_image(FileInterface* f,
       if (input_bytes == 0)
         break;                  // Done, we consumed all chunk
     }
-    else
+    else {
       input_bytes = compressed.size();
+    }
 
     size_t bytes_read = f->readBytes(&compressed[0], input_bytes);
     zstream.next_in = (Bytef*)&compressed[0];
@@ -583,6 +591,46 @@ void read_compressed_image(FileInterface* f,
     throw base::Exception("ZLib error %d in inflateEnd().", err);
 }
 
+void read_compressed_image(FileInterface* f,
+                           DecodeDelegate* delegate,
+                           doc::Image* image,
+                           const AsepriteHeader* header,
+                           const size_t chunk_end)
+{
+  // Try to read pixel data
+  try {
+    switch (image->pixelFormat()) {
+
+      case doc::IMAGE_RGB:
+        read_compressed_image_templ<doc::RgbTraits>(
+          f, delegate, image, header, chunk_end);
+        break;
+
+      case doc::IMAGE_GRAYSCALE:
+        read_compressed_image_templ<doc::GrayscaleTraits>(
+          f, delegate, image, header, chunk_end);
+        break;
+
+      case doc::IMAGE_INDEXED:
+        read_compressed_image_templ<doc::IndexedTraits>(
+          f, delegate, image, header, chunk_end);
+        break;
+
+      case doc::IMAGE_TILEMAP:
+        read_compressed_image_templ<doc::TilemapTraits>(
+          f, delegate, image, header, chunk_end);
+        break;
+    }
+  }
+  // OK, in case of error we can show the problem, but continue
+  // loading more cels.
+  catch (const std::exception& e) {
+    delegate->error(e.what());
+  }
+}
+
+} // anonymous namespace
+
 //////////////////////////////////////////////////////////////////////
 // Cel Chunk
 //////////////////////////////////////////////////////////////////////
@@ -591,8 +639,8 @@ doc::Cel* AsepriteDecoder::readCelChunk(doc::Sprite* sprite,
                                         doc::LayerList& allLayers,
                                         doc::frame_t frame,
                                         doc::PixelFormat pixelFormat,
-                                        AsepriteHeader* header,
-                                        size_t chunk_end)
+                                        const AsepriteHeader* header,
+                                        const size_t chunk_end)
 {
   // Read chunk data
   doc::layer_t layer_index = read16();
@@ -687,33 +735,29 @@ doc::Cel* AsepriteDecoder::readCelChunk(doc::Sprite* sprite,
 
       if (w > 0 && h > 0) {
         doc::ImageRef image(doc::Image::create(pixelFormat, w, h));
+        read_compressed_image(f(), delegate(), image.get(), header, chunk_end);
 
-        // Try to read pixel data
-        try {
-          switch (image->pixelFormat()) {
+        cel.reset(new doc::Cel(frame, image));
+        cel->setPosition(x, y);
+        cel->setOpacity(opacity);
+      }
+      break;
+    }
 
-            case doc::IMAGE_RGB:
-              read_compressed_image<doc::RgbTraits>(
-                f(), delegate(), image.get(), chunk_end, header);
-              break;
-
-            case doc::IMAGE_GRAYSCALE:
-              read_compressed_image<doc::GrayscaleTraits>(
-                f(), delegate(), image.get(), chunk_end, header);
-              break;
-
-            case doc::IMAGE_INDEXED:
-              read_compressed_image<doc::IndexedTraits>(
-                f(), delegate(), image.get(), chunk_end, header);
-              break;
-          }
-        }
-        // OK, in case of error we can show the problem, but continue
-        // loading more cels.
-        catch (const std::exception& e) {
-          delegate()->error(e.what());
-        }
+    case ASE_FILE_COMPRESSED_TILEMAP: {
+      // Read width and height
+      int w = read16();
+      int h = read16();
+      int bitsPerTile = read16();
+      uint32_t tileIDkMask = read32();
+      uint32_t flipxMask = read32();
+      uint32_t fileyMask = read32();
+      uint32_t rot90Mask = read32();
+      readPadding(10);
 
+      if (w > 0 && h > 0) {
+        doc::ImageRef image(doc::Image::create(doc::IMAGE_TILEMAP, w, h));
+        read_compressed_image(f(), delegate(), image.get(), header, chunk_end);
         cel.reset(new doc::Cel(frame, image));
         cel->setPosition(x, y);
         cel->setOpacity(opacity);
@@ -925,4 +969,45 @@ doc::Slice* AsepriteDecoder::readSliceChunk(doc::Slices& slices)
   return slice.release();
 }
 
+void AsepriteDecoder::readTilesetChunk(doc::Sprite* sprite,
+                                       const AsepriteHeader* header)
+{
+  const doc::tileset_index id = read32();
+  const uint32_t flags = read32();
+  const int w = read16();
+  const int h = read16();
+  readPadding(20);
+  const std::string name = readString();
+
+  // TODO add support to load the external filename
+  if (flags & 1) {
+    // Ignore fields
+    readString();               // external filename
+    read32();                   // tileset ID in the external file
+  }
+
+  if (flags & 2) {
+    const doc::tile_index ntiles = read32();
+
+    doc::Grid grid(gfx::Size(w, h));
+    auto tileset = new doc::Tileset(sprite, grid, ntiles);
+    tileset->setName(name);
+
+    for (doc::tile_index i=0; i<ntiles; ++i) {
+      read32();                 // Flags (ignore)
+      const size_t dataSize = read32(); // Size of compressed data
+      const size_t dataBeg = f()->tell();
+      const size_t dataEnd = dataBeg+dataSize;
+
+      doc::ImageRef tile(doc::Image::create(sprite->pixelFormat(), w, h));
+      read_compressed_image(f(), delegate(), tile.get(), header, dataEnd);
+      tileset->set(i, tile);
+
+      f()->seek(dataEnd);
+    }
+
+    sprite->tilesets()->set(id, tileset);
+  }
+}
+
 } // namespace dio
diff --git a/src/dio/aseprite_decoder.h b/src/dio/aseprite_decoder.h
index d1b5607e1..71ac11337 100644
--- a/src/dio/aseprite_decoder.h
+++ b/src/dio/aseprite_decoder.h
@@ -1,5 +1,5 @@
 // Aseprite Document IO Library
-// Copyright (c) 2018 Igara Studio S.A.
+// Copyright (c) 2018-2019 Igara Studio S.A.
 // Copyright (c) 2017 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -50,8 +50,8 @@ private:
                          doc::LayerList& allLayers,
                          doc::frame_t frame,
                          doc::PixelFormat pixelFormat,
-                         AsepriteHeader* header,
-                         size_t chunk_end);
+                         const AsepriteHeader* header,
+                         const size_t chunk_end);
   void readCelExtraChunk(doc::Cel* cel);
   void readColorProfile(doc::Sprite* sprite);
   doc::Mask* readMaskChunk();
@@ -59,6 +59,8 @@ private:
   void readSlicesChunk(doc::Slices& slices);
   doc::Slice* readSliceChunk(doc::Slices& slices);
   void readUserDataChunk(doc::UserData* userData);
+  void readTilesetChunk(doc::Sprite* sprite,
+                        const AsepriteHeader* header);
 };
 
 } // namespace dio
diff --git a/src/dio/pixel_io.h b/src/dio/pixel_io.h
index 3c9cf2e75..c0741b281 100644
--- a/src/dio/pixel_io.h
+++ b/src/dio/pixel_io.h
@@ -46,22 +46,21 @@ public:
   }
   void read_scanline(doc::RgbTraits::address_t address,
                      int w, uint8_t* buffer) {
-    for (int x=0; x<w; ++x) {
+    for (int x=0; x<w; ++x, ++address) {
       r = *(buffer++);
       g = *(buffer++);
       b = *(buffer++);
       a = *(buffer++);
-      *(address++) = doc::rgba(r, g, b, a);
+      *address = doc::rgba(r, g, b, a);
     }
   }
   void write_scanline(doc::RgbTraits::address_t address,
                       int w, uint8_t* buffer) {
-    for (int x=0; x<w; ++x) {
+    for (int x=0; x<w; ++x, ++address) {
       *(buffer++) = doc::rgba_getr(*address);
       *(buffer++) = doc::rgba_getg(*address);
       *(buffer++) = doc::rgba_getb(*address);
       *(buffer++) = doc::rgba_geta(*address);
-      ++address;
     }
   }
 };
@@ -82,19 +81,18 @@ public:
   void read_scanline(doc::GrayscaleTraits::address_t address,
                      int w, uint8_t* buffer)
   {
-    for (int x=0; x<w; ++x) {
+    for (int x=0; x<w; ++x, ++address) {
       k = *(buffer++);
       a = *(buffer++);
-      *(address++) = doc::graya(k, a);
+      *address = doc::graya(k, a);
     }
   }
   void write_scanline(doc::GrayscaleTraits::address_t address,
                       int w, uint8_t* buffer)
   {
-    for (int x=0; x<w; ++x) {
+    for (int x=0; x<w; ++x, ++address) {
       *(buffer++) = doc::graya_getv(*address);
       *(buffer++) = doc::graya_geta(*address);
-      ++address;
     }
   }
 };
@@ -118,6 +116,35 @@ public:
   }
 };
 
+template<>
+class PixelIO<doc::TilemapTraits> {
+  int b1, b2, b3, b4;
+public:
+  doc::TilemapTraits::pixel_t read_pixel(FileInterface* f) {
+    int b1 = f->read8();
+    int b2 = f->read8();
+    int b3 = f->read8();
+    int b4 = f->read8();
+
+    if (f->ok()) {
+      // Little endian
+      return ((b4 << 24) | (b3 << 16) | (b2 << 8) | b1);
+    }
+    else
+      return 0;
+  }
+  void read_scanline(doc::TilemapTraits::address_t address,
+                     int w, uint8_t* buffer) {
+    for (int x=0; x<w; ++x, ++address) {
+      b1 = *(buffer++);
+      b2 = *(buffer++);
+      b3 = *(buffer++);
+      b4 = *(buffer++);
+      *address = ((b4 << 24) | (b3 << 16) | (b2 << 8) | b1);
+    }
+  }
+};
+
 } // namespace dio
 
 #endif
diff --git a/src/doc/CMakeLists.txt b/src/doc/CMakeLists.txt
index d1c5973d1..0045431db 100644
--- a/src/doc/CMakeLists.txt
+++ b/src/doc/CMakeLists.txt
@@ -1,5 +1,6 @@
 # Aseprite Document Library
-# Copyright (C) 2001-2018 David Capello
+# Copyright (C) 2019  Igara Studio S.A.
+# Copyright (C) 2001-2018  David Capello
 
 if(WIN32)
   add_definitions(-D_CRT_SECURE_NO_WARNINGS)
@@ -36,6 +37,8 @@ add_library(doc-lib
   file/gpl_file.cpp
   file/hex_file.cpp
   file/pal_file.cpp
+  grid.cpp
+  grid_io.cpp
   handle_anidir.cpp
   image.cpp
   image_impl.cpp
@@ -43,6 +46,7 @@ add_library(doc-lib
   layer.cpp
   layer_io.cpp
   layer_list.cpp
+  layer_tilemap.cpp
   mask.cpp
   mask_boundaries.cpp
   mask_io.cpp
@@ -66,6 +70,9 @@ add_library(doc-lib
   tag.cpp
   tag_io.cpp
   tags.cpp
+  tileset.cpp
+  tileset_io.cpp
+  tilesets.cpp
   user_data_io.cpp)
 
 # TODO Remove 'os' as dependency and move conversion_to_surface.cpp/h files
diff --git a/src/doc/algorithm/fill_selection.cpp b/src/doc/algorithm/fill_selection.cpp
index 0caf9191e..ade09781a 100644
--- a/src/doc/algorithm/fill_selection.cpp
+++ b/src/doc/algorithm/fill_selection.cpp
@@ -35,6 +35,7 @@ void fill_selection(Image* image,
     for (int u=0; u<maskBounds.w; ++u, ++it) {
       ASSERT(it != maskBits.end());
       if (*it) {
+        // TODO use iterators
         put_pixel(image,
                   u + offset.x,
                   v + offset.y, color);
diff --git a/src/doc/algorithm/shift_image.cpp b/src/doc/algorithm/shift_image.cpp
index c89967eaf..a3d013b2f 100644
--- a/src/doc/algorithm/shift_image.cpp
+++ b/src/doc/algorithm/shift_image.cpp
@@ -106,7 +106,10 @@ ImageRef shift_image_with_mask(const Cel* cel,
 
   // Bounds and Image shrinking (we have to fit compound image (compImage) and bounds (compCelBounds))
   gfx::Rect newBounds = compImage->bounds();
-  if (algorithm::shrink_bounds(compImage.get(), newBounds, compImage->maskColor())) {
+  if (algorithm::shrink_bounds(compImage.get(),
+                               compImage->maskColor(),
+                               nullptr,
+                               newBounds)) {
     compCelBounds.offset(newBounds.x, newBounds.y);
     compCelBounds.setSize(newBounds.size());
   }
diff --git a/src/doc/algorithm/shrink_bounds.cpp b/src/doc/algorithm/shrink_bounds.cpp
index 6df00eec4..32d8e1975 100644
--- a/src/doc/algorithm/shrink_bounds.cpp
+++ b/src/doc/algorithm/shrink_bounds.cpp
@@ -11,9 +11,15 @@
 
 #include "doc/algorithm/shrink_bounds.h"
 
+#include "doc/cel.h"
+#include "doc/grid.h"
 #include "doc/image.h"
 #include "doc/image_impl.h"
+#include "doc/layer.h"
+#include "doc/layer_tilemap.h"
+#include "doc/primitives.h"
 #include "doc/primitives_fast.h"
+#include "doc/tileset.h"
 
 #include <thread>
 
@@ -47,6 +53,12 @@ bool is_same_pixel<IndexedTraits>(color_t pixel1, color_t pixel2)
   return pixel1 == pixel2;
 }
 
+template<>
+bool is_same_pixel<BitmapTraits>(color_t pixel1, color_t pixel2)
+{
+  return pixel1 == pixel2;
+}
+
 template<typename ImageTraits>
 bool shrink_bounds_left_templ(const Image* image, gfx::Rect& bounds, color_t refpixel, int rowSize)
 {
@@ -223,46 +235,171 @@ bool shrink_bounds_templ2(const Image* a, const Image* b, gfx::Rect& bounds)
   return (!bounds.isEmpty());
 }
 
+bool shrink_bounds_tilemap(const Image* image,
+                           const color_t refpixel,
+                           const Layer* layer,
+                           gfx::Rect& bounds)
+{
+  ASSERT(layer);
+  if (!layer)
+    return false;
+
+  ASSERT(layer->isTilemap());
+  if (!layer->isTilemap())
+    return false;
+
+  const Tileset* tileset =
+    static_cast<const LayerTilemap*>(layer)->tileset();
+
+  bool shrink;
+  int u, v;
+
+  // Shrink left side
+  for (u=bounds.x; u<bounds.x+bounds.w; ++u) {
+    shrink = true;
+    for (v=bounds.y; v<bounds.y+bounds.h; ++v) {
+      const tile_t tile = get_pixel_fast<TilemapTraits>(image, u, v);
+      const tile_t tileIndex = tile_geti(tile);
+      const ImageRef tileImg = tileset->get(tileIndex);
+
+      if (tileImg && !is_plain_image(tileImg.get(), refpixel)) {
+        shrink = false;
+        break;
+      }
+    }
+    if (!shrink)
+      break;
+    ++bounds.x;
+    --bounds.w;
+  }
+
+  // Shrink right side
+  for (u=bounds.x+bounds.w-1; u>=bounds.x; --u) {
+    shrink = true;
+    for (v=bounds.y; v<bounds.y+bounds.h; ++v) {
+      const tile_t tile = get_pixel_fast<TilemapTraits>(image, u, v);
+      const tile_t tileIndex = tile_geti(tile);
+      const ImageRef tileImg = tileset->get(tileIndex);
+
+      if (tileImg && !is_plain_image(tileImg.get(), refpixel)) {
+        shrink = false;
+        break;
+      }
+    }
+    if (!shrink)
+      break;
+    --bounds.w;
+  }
+
+  // Shrink top side
+  for (v=bounds.y; v<bounds.y+bounds.h; ++v) {
+    shrink = true;
+    for (u=bounds.x; u<bounds.x+bounds.w; ++u) {
+      const tile_t tile = get_pixel_fast<TilemapTraits>(image, u, v);
+      const tile_t tileIndex = tile_geti(tile);
+      const ImageRef tileImg = tileset->get(tileIndex);
+
+      if (tileImg && !is_plain_image(tileImg.get(), refpixel)) {
+        shrink = false;
+        break;
+      }
+    }
+    if (!shrink)
+      break;
+    ++bounds.y;
+    --bounds.h;
+  }
+
+  // Shrink bottom side
+  for (v=bounds.y+bounds.h-1; v>=bounds.y; --v) {
+    shrink = true;
+    for (u=bounds.x; u<bounds.x+bounds.w; ++u) {
+      const tile_t tile = get_pixel_fast<TilemapTraits>(image, u, v);
+      const tile_t tileIndex = tile_geti(tile);
+      const ImageRef tileImg = tileset->get(tileIndex);
+
+      if (tileImg && !is_plain_image(tileImg.get(), refpixel)) {
+        shrink = false;
+        break;
+      }
+    }
+    if (!shrink)
+      break;
+    --bounds.h;
+  }
+
+  return (!bounds.isEmpty());
+}
+
 }
 
 bool shrink_bounds(const Image* image,
-                   const gfx::Rect& start_bounds,
-                   gfx::Rect& bounds,
-                   color_t refpixel)
+                   const color_t refpixel,
+                   const Layer* layer,
+                   const gfx::Rect& startBounds,
+                   gfx::Rect& bounds)
 {
-  bounds = (start_bounds & image->bounds());
+  bounds = (startBounds & image->bounds());
   switch (image->pixelFormat()) {
     case IMAGE_RGB:       return shrink_bounds_templ<RgbTraits>(image, bounds, refpixel);
     case IMAGE_GRAYSCALE: return shrink_bounds_templ<GrayscaleTraits>(image, bounds, refpixel);
     case IMAGE_INDEXED:   return shrink_bounds_templ<IndexedTraits>(image, bounds, refpixel);
-    case IMAGE_BITMAP:
-      // Not supported
-      break;
+    case IMAGE_BITMAP:    return shrink_bounds_templ<BitmapTraits>(image, bounds, refpixel);
+    case IMAGE_TILEMAP:   return shrink_bounds_tilemap(image, refpixel, layer, bounds);
   }
   ASSERT(false);
-  bounds = start_bounds;
+  bounds = startBounds;
   return true;
 }
 
-bool shrink_bounds(const Image* image, gfx::Rect& bounds, color_t refpixel)
+bool shrink_bounds(const Image* image,
+                   const color_t refpixel,
+                   const Layer* layer,
+                   gfx::Rect& bounds)
 {
-  return shrink_bounds(image, image->bounds(), bounds, refpixel);
+  return shrink_bounds(image, refpixel, layer, image->bounds(), bounds);
 }
 
-bool shrink_bounds2(const Image* a, const Image* b,
-                    const gfx::Rect& start_bounds,
+bool shrink_cel_bounds(const Cel* cel,
+                       const color_t refpixel,
+                       gfx::Rect& bounds)
+{
+  if (shrink_bounds(cel->image(), refpixel, cel->layer(), bounds)) {
+    // For tilemaps, we have to convert imgBounds (in tiles
+    // coordinates) to canvas coordinates using the Grid specs.
+    if (cel->layer()->isTilemap()) {
+      doc::LayerTilemap* tilemapLayer = static_cast<doc::LayerTilemap*>(cel->layer());
+      doc::Tileset* tileset = tilemapLayer->tileset();
+      doc::Grid grid = tileset->grid();
+      grid.origin(grid.origin() + cel->position());
+      bounds = grid.tileToCanvas(bounds);
+    }
+    else {
+      bounds.offset(cel->position());
+    }
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+bool shrink_bounds2(const Image* a,
+                    const Image* b,
+                    const gfx::Rect& startBounds,
                     gfx::Rect& bounds)
 {
   ASSERT(a && b);
   ASSERT(a->bounds() == b->bounds());
 
-  bounds = (start_bounds & a->bounds());
+  bounds = (startBounds & a->bounds());
 
   switch (a->pixelFormat()) {
     case IMAGE_RGB:       return shrink_bounds_templ2<RgbTraits>(a, b, bounds);
     case IMAGE_GRAYSCALE: return shrink_bounds_templ2<GrayscaleTraits>(a, b, bounds);
     case IMAGE_INDEXED:   return shrink_bounds_templ2<IndexedTraits>(a, b, bounds);
     case IMAGE_BITMAP:    return shrink_bounds_templ2<BitmapTraits>(a, b, bounds);
+    // case IMAGE_TILEMAP:   return shrink_bounds_templ2<TilemapTraits>(a, b, bounds);
   }
   ASSERT(false);
   return false;
diff --git a/src/doc/algorithm/shrink_bounds.h b/src/doc/algorithm/shrink_bounds.h
index 0f2d3ab6f..691b2ef19 100644
--- a/src/doc/algorithm/shrink_bounds.h
+++ b/src/doc/algorithm/shrink_bounds.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -13,22 +14,31 @@
 #include "doc/color.h"
 
 namespace doc {
+  class Cel;
   class Image;
+  class Layer;
 
   namespace algorithm {
 
+    // The layer is used in case the image is a tilemap and we need its tileset.
     bool shrink_bounds(const Image* image,
-                       const gfx::Rect& start_bounds,
-                       gfx::Rect& bounds,
-                       color_t refpixel);
+                       const color_t refpixel,
+                       const Layer* layer,
+                       const gfx::Rect& startBounds,
+                       gfx::Rect& bounds);
 
     bool shrink_bounds(const Image* image,
-                       gfx::Rect& bounds,
-                       color_t refpixel);
+                       const color_t refpixel,
+                       const Layer* layer,
+                       gfx::Rect& bounds);
+
+    bool shrink_cel_bounds(const Cel* cel,
+                           const color_t refpixel,
+                           gfx::Rect& bounds);
 
     bool shrink_bounds2(const Image* a,
                         const Image* b,
-                        const gfx::Rect& start_bounds,
+                        const gfx::Rect& startBounds,
                         gfx::Rect& bounds);
 
   } // algorithm
diff --git a/src/doc/cel.cpp b/src/doc/cel.cpp
index 6c67ff34b..b0efc7b4b 100644
--- a/src/doc/cel.cpp
+++ b/src/doc/cel.cpp
@@ -148,8 +148,11 @@ void Cel::setParentLayer(LayerImage* layer)
 void Cel::fixupImage()
 {
   // Change the mask color to the sprite mask color
-  if (m_layer && image())
+  if (m_layer && image()) {
     image()->setMaskColor(m_layer->sprite()->transparentColor());
+    ASSERT(m_data);
+    m_data->adjustBounds(m_layer);
+  }
 }
 
 } // namespace doc
diff --git a/src/doc/cel_data.cpp b/src/doc/cel_data.cpp
index b83b83883..ac9acc2b5 100644
--- a/src/doc/cel_data.cpp
+++ b/src/doc/cel_data.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -10,10 +11,12 @@
 
 #include "doc/cel_data.h"
 
-#include "gfx/rect.h"
 #include "doc/image.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/sprite.h"
+#include "doc/tileset.h"
+#include "gfx/rect.h"
 
 namespace doc {
 
@@ -43,13 +46,38 @@ CelData::~CelData()
   delete m_boundsF;
 }
 
-void CelData::setImage(const ImageRef& image)
+void CelData::setImage(const ImageRef& image, Layer* layer)
 {
   ASSERT(image.get());
 
   m_image = image;
-  m_bounds.w = image->width();
-  m_bounds.h = image->height();
+  adjustBounds(layer);
+}
+
+void CelData::setPosition(const gfx::Point& pos)
+{
+  m_bounds.setOrigin(pos);
+}
+
+void CelData::adjustBounds(Layer* layer)
+{
+  ASSERT(m_image);
+  if (m_image->pixelFormat() == IMAGE_TILEMAP) {
+    Tileset* tileset = nullptr;
+    if (layer && layer->isTilemap())
+      tileset = static_cast<LayerTilemap*>(layer)->tileset();
+    if (tileset) {
+      gfx::Size canvasSize =
+        tileset->grid().tilemapSizeToCanvas(
+          gfx::Size(m_image->width(),
+                    m_image->height()));
+      m_bounds.w = canvasSize.w;
+      m_bounds.h = canvasSize.h;
+      return;
+    }
+  }
+  m_bounds.w = m_image->width();
+  m_bounds.h = m_image->height();
 }
 
 } // namespace doc
diff --git a/src/doc/cel_data.h b/src/doc/cel_data.h
index c10902148..8e535e7b4 100644
--- a/src/doc/cel_data.h
+++ b/src/doc/cel_data.h
@@ -1,6 +1,6 @@
 // Aseprite Document Library
 // Copyright (C) 2019  Igara Studio S.A.
-// Copyright (c) 2001-2016 David Capello
+// Copyright (C) 2001-2016  David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -18,6 +18,9 @@
 
 namespace doc {
 
+  class Layer;
+  class Tileset;
+
   class CelData : public WithUserData {
   public:
     CelData(const ImageRef& image);
@@ -30,8 +33,8 @@ namespace doc {
     Image* image() const { return const_cast<Image*>(m_image.get()); };
     ImageRef imageRef() const { return m_image; }
 
-    void setImage(const ImageRef& image);
-    void setPosition(const gfx::Point& pos) { m_bounds.setOrigin(pos); }
+    void setImage(const ImageRef& image, Layer* layer);
+    void setPosition(const gfx::Point& pos);
     void setOpacity(int opacity) { m_opacity = opacity; }
 
     void setBounds(const gfx::Rect& bounds) {
@@ -60,6 +63,8 @@ namespace doc {
       return sizeof(CelData) + m_image->getMemSize();
     }
 
+    void adjustBounds(Layer* layer);
+
   private:
     ImageRef m_image;
     int m_opacity;
diff --git a/src/doc/cels_range.cpp b/src/doc/cels_range.cpp
index 91911a2e3..56fc20279 100644
--- a/src/doc/cels_range.cpp
+++ b/src/doc/cels_range.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
diff --git a/src/doc/color_mode.h b/src/doc/color_mode.h
index f9675159a..3878f7642 100644
--- a/src/doc/color_mode.h
+++ b/src/doc/color_mode.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2014 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -14,7 +15,8 @@ namespace doc {
     RGB,
     GRAYSCALE,
     INDEXED,
-    BITMAP
+    BITMAP,
+    TILEMAP,
   };
 
 } // namespace doc
diff --git a/src/doc/doc.h b/src/doc/doc.h
index 17203c193..55c0e058b 100644
--- a/src/doc/doc.h
+++ b/src/doc/doc.h
@@ -23,6 +23,7 @@
 #include "doc/image_ref.h"
 #include "doc/images_map.h"
 #include "doc/layer.h"
+#include "doc/layer_tilemap.h"
 #include "doc/mask.h"
 #include "doc/object.h"
 #include "doc/palette.h"
@@ -38,5 +39,8 @@
 #include "doc/sprite.h"
 #include "doc/tag.h"
 #include "doc/tags.h"
+#include "doc/tile.h"
+#include "doc/tileset.h"
+#include "doc/tilesets.h"
 
 #endif
diff --git a/src/doc/grid.cpp b/src/doc/grid.cpp
new file mode 100644
index 000000000..05d2398c0
--- /dev/null
+++ b/src/doc/grid.cpp
@@ -0,0 +1,163 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/grid.h"
+
+#include "doc/image.h"
+#include "doc/image_impl.h"
+#include "doc/image_ref.h"
+#include "doc/primitives.h"
+#include "gfx/point.h"
+#include "gfx/rect.h"
+#include "gfx/region.h"
+#include "gfx/size.h"
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+#include <vector>
+
+namespace doc {
+
+// static
+Grid Grid::MakeRect(const gfx::Size& sz)
+{
+  return Grid(sz);
+}
+
+// Converts a tile position into a canvas position
+gfx::Point Grid::tileToCanvas(const gfx::Point& tile) const
+{
+  gfx::Point result;
+  result.x = tile.x * m_tileOffset.x + m_origin.x;
+  result.y = tile.y * m_tileOffset.y + m_origin.y;
+  if (tile.y & 1) // Odd row
+    result += m_oddRowOffset;
+  if (tile.x & 1) // Odd column
+    result += m_oddColOffset;
+  return result;
+}
+
+gfx::Rect Grid::tileToCanvas(const gfx::Rect& tileBounds) const
+{
+  gfx::Point pt1 = tileToCanvas(tileBounds.origin());
+  gfx::Point pt2 = tileToCanvas(tileBounds.point2());
+  return gfx::Rect(pt1, pt2);
+}
+
+gfx::Point Grid::canvasToTile(const gfx::Point& canvasPoint) const
+{
+  gfx::Point tile;
+  std::div_t divx = std::div((canvasPoint.x - m_origin.x), m_tileSize.w);
+  std::div_t divy = std::div((canvasPoint.y - m_origin.y), m_tileSize.h);
+  tile.x = divx.quot;
+  tile.y = divy.quot;
+  if (canvasPoint.x < m_origin.x && divx.rem) --tile.x;
+  if (canvasPoint.y < m_origin.y && divy.rem) --tile.y;
+
+  if (m_oddRowOffset.x != 0 || m_oddRowOffset.y != 0 ||
+      m_oddColOffset.x != 0 || m_oddColOffset.y != 0) {
+    gfx::Point bestTile = tile;
+    int bestDist = std::numeric_limits<int>::max();
+    for (int v=-1; v<=2; ++v) {
+      for (int u=-1; u<=2; ++u) {
+        gfx::Point neighbor(tile.x+u, tile.y+v);
+        gfx::Point neighborCanvas = tileToCanvas(neighbor);
+
+        if (hasMask()) {
+          if (doc::get_pixel(m_mask.get(),
+                             canvasPoint.x-neighborCanvas.x,
+                             canvasPoint.y-neighborCanvas.y))
+            return neighbor;
+        }
+
+        gfx::Point delta = neighborCanvas+m_tileCenter-canvasPoint;
+        int dist = delta.x*delta.x + delta.y*delta.y;
+        if (bestDist > dist) {
+          bestDist = dist;
+          bestTile = neighbor;
+        }
+      }
+    }
+    tile = bestTile;
+  }
+
+  return tile;
+}
+
+gfx::Rect Grid::canvasToTile(const gfx::Rect& canvasBounds) const
+{
+  gfx::Point pt1 = canvasToTile(canvasBounds.origin());
+  gfx::Point pt2 = canvasToTile(gfx::Point(canvasBounds.x2()-1,
+                                           canvasBounds.y2()-1));
+  return gfx::Rect(pt1, gfx::Size(pt2.x - pt1.x + 1,
+                                  pt2.y - pt1.y + 1));
+}
+
+gfx::Size Grid::tilemapSizeToCanvas(const gfx::Size& tilemapSize) const
+{
+  gfx::Point pt = tileToCanvas(gfx::Point(tilemapSize.w-1,
+                                          tilemapSize.h-1));
+  return gfx::Size(pt.x + m_tileSize.w,
+                   pt.y + m_tileSize.h);
+}
+
+gfx::Rect Grid::tileBoundsInCanvas(const gfx::Point& tile) const
+{
+  return gfx::Rect(tileToCanvas(tile), m_tileSize);
+}
+
+gfx::Rect Grid::alignBounds(const gfx::Rect& bounds) const
+{
+  gfx::Point pt1 = canvasToTile(bounds.origin());
+  gfx::Point pt2 = canvasToTile(gfx::Point(bounds.x2()-1,
+                                           bounds.y2()-1));
+  return
+    tileBoundsInCanvas(pt1) |
+    tileBoundsInCanvas(pt2);
+}
+
+std::vector<gfx::Point> Grid::tilesInCanvasRegion(const gfx::Region& rgn) const
+{
+  std::vector<gfx::Point> result;
+  if (rgn.isEmpty())
+    return result;
+
+  const gfx::Rect bounds = canvasToTile(rgn.bounds());
+  if (bounds.w < 1 ||
+      bounds.h < 1)
+    return result;
+
+  ImageRef tmp(Image::create(IMAGE_BITMAP, bounds.w, bounds.h));
+  const gfx::Rect tmpBounds = tmp->bounds();
+  tmp->clear(0);
+
+  for (const gfx::Rect& rc : rgn) {
+    gfx::Rect tileBounds = canvasToTile(rc);
+    tileBounds.x -= bounds.x;
+    tileBounds.y -= bounds.y;
+    tileBounds &= tmpBounds;
+    if (!tileBounds.isEmpty())
+      tmp->fillRect(tileBounds.x,
+                    tileBounds.y,
+                    tileBounds.x2()-1,
+                    tileBounds.y2()-1, 1);
+  }
+
+  const LockImageBits<BitmapTraits> bits(tmp.get());
+  for (auto it=bits.begin(), end=bits.end(); it!=end; ++it) {
+    if (*it)
+      result.push_back(gfx::Point(it.x()+bounds.x,
+                                  it.y()+bounds.y));
+  }
+  return result;
+}
+
+} // namespace doc
diff --git a/src/doc/grid.h b/src/doc/grid.h
new file mode 100644
index 000000000..e94c5c926
--- /dev/null
+++ b/src/doc/grid.h
@@ -0,0 +1,76 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_GRID_H_INCLUDED
+#define DOC_GRID_H_INCLUDED
+#pragma once
+
+#include "doc/image_ref.h"
+#include "gfx/fwd.h"
+#include "gfx/point.h"
+#include "gfx/size.h"
+
+namespace doc {
+
+  class Grid {
+  public:
+    Grid(const gfx::Size& sz = gfx::Size(16, 16))
+      : m_tileSize(sz)
+      , m_origin(0, 0)
+      , m_tileCenter(gfx::Point(sz.w/2, sz.h/2))
+      , m_tileOffset(gfx::Point(sz.w, sz.h))
+      , m_oddRowOffset(0, 0)
+      , m_oddColOffset(0, 0)
+      , m_mask(nullptr) { }
+
+    static Grid MakeRect(const gfx::Size& sz);
+
+    gfx::Size tileSize() const { return m_tileSize; }
+    gfx::Point origin() const { return m_origin; }
+    gfx::Point tileCenter() const { return m_tileCenter; }
+    gfx::Point tileOffset() const { return m_tileOffset; }
+    gfx::Point oddRowOffset() const { return m_oddRowOffset; }
+    gfx::Point oddColOffset() const { return m_oddColOffset; }
+
+    void tileSize(const gfx::Size& tileSize) { m_tileSize = tileSize; }
+    void origin(const gfx::Point& origin) { m_origin = origin; }
+    void tileCenter(const gfx::Point& tileCenter) { m_tileCenter = tileCenter; }
+    void tileOffset(const gfx::Point& tileOffset) { m_tileOffset = tileOffset; }
+    void oddRowOffset(const gfx::Point& oddRowOffset) { m_oddRowOffset = oddRowOffset; }
+    void oddColOffset(const gfx::Point& oddColOffset) { m_oddColOffset = oddColOffset; }
+
+    // Converts a tile position into a canvas position
+    gfx::Point tileToCanvas(const gfx::Point& tile) const;
+    gfx::Rect tileToCanvas(const gfx::Rect& tileBounds) const;
+
+    // Converts a canvas position/rectangle into a tile position
+    gfx::Point canvasToTile(const gfx::Point& canvasPoint) const;
+    gfx::Rect canvasToTile(const gfx::Rect& canvasBounds) const;
+
+    gfx::Size tilemapSizeToCanvas(const gfx::Size& tilemapSize) const;
+    gfx::Rect tileBoundsInCanvas(const gfx::Point& tile) const;
+    gfx::Rect alignBounds(const gfx::Rect& bounds) const;
+
+    bool hasMask() const { return m_mask.get() != nullptr; }
+    doc::ImageRef mask() const { return m_mask; }
+    void setMask(const doc::ImageRef& mask) { m_mask = mask; }
+
+    // Returns an array of tile positions that are touching the given region in the canvas
+    std::vector<gfx::Point> tilesInCanvasRegion(const gfx::Region& rgn) const;
+
+  private:
+    gfx::Size m_tileSize;
+    gfx::Point m_origin;
+    gfx::Point m_tileCenter;
+    gfx::Point m_tileOffset;
+    gfx::Point m_oddRowOffset;
+    gfx::Point m_oddColOffset;
+    doc::ImageRef m_mask;
+  };
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/grid_io.cpp b/src/doc/grid_io.cpp
new file mode 100644
index 000000000..8c2cca6f9
--- /dev/null
+++ b/src/doc/grid_io.cpp
@@ -0,0 +1,84 @@
+// Aseprite Document Library
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/grid_io.h"
+
+#include "base/serialization.h"
+#include "doc/image.h"
+#include "doc/image_io.h"
+#include "doc/grid.h"
+
+#include <iostream>
+
+namespace doc {
+
+using namespace base::serialization;
+using namespace base::serialization::little_endian;
+
+bool write_grid(std::ostream& os, const Grid& grid)
+{
+  write32(os, grid.tileSize().w);
+  write32(os, grid.tileSize().h);
+  write32(os, grid.origin().x);
+  write32(os, grid.origin().y);
+  write32(os, grid.tileCenter().x);
+  write32(os, grid.tileCenter().y);
+  write32(os, grid.tileOffset().x);
+  write32(os, grid.tileOffset().y);
+  write32(os, grid.oddRowOffset().x);
+  write32(os, grid.oddRowOffset().y);
+  write32(os, grid.oddColOffset().x);
+  write32(os, grid.oddColOffset().y);
+  write8(os, grid.hasMask());
+  if (grid.hasMask())
+    return write_image(os, grid.mask().get());
+  else
+    return true;
+}
+
+Grid read_grid(std::istream& is, bool setId)
+{
+  gfx::Size tileSize;
+  gfx::Point origin;
+  gfx::Point tileCenter;
+  gfx::Point tileOffset;
+  gfx::Point oddRowOffset;
+  gfx::Point oddColOffset;
+  tileSize.w = read32(is);
+  tileSize.h = read32(is);
+  origin.x = read32(is);
+  origin.y = read32(is);
+  tileCenter.x = read32(is);
+  tileCenter.y = read32(is);
+  tileOffset.x = read32(is);
+  tileOffset.y = read32(is);
+  oddRowOffset.x = read32(is);
+  oddRowOffset.y = read32(is);
+  oddColOffset.x = read32(is);
+  oddColOffset.y = read32(is);
+  bool hasMask = read8(is);
+
+  Grid grid;
+  grid.tileSize(tileSize);
+  grid.origin(origin);
+  grid.tileCenter(tileCenter);
+  grid.tileOffset(tileOffset);
+  grid.oddRowOffset(oddRowOffset);
+  grid.oddColOffset(oddColOffset);
+
+  if (hasMask) {
+    ImageRef mask(read_image(is));
+    if (mask)
+      grid.setMask(mask);
+  }
+  return grid;
+}
+
+} // namespace doc
diff --git a/src/doc/grid_io.h b/src/doc/grid_io.h
new file mode 100644
index 000000000..93aa1edd1
--- /dev/null
+++ b/src/doc/grid_io.h
@@ -0,0 +1,22 @@
+// Aseprite Document Library
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_GRID_IO_H_INCLUDED
+#define DOC_GRID_IO_H_INCLUDED
+#pragma once
+
+#include <iosfwd>
+
+namespace doc {
+
+  class Grid;
+
+  bool write_grid(std::ostream& os, const Grid& grid);
+  Grid read_grid(std::istream& is, bool setId = true);
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/grid_tests.cpp b/src/doc/grid_tests.cpp
new file mode 100644
index 000000000..abe8bcc51
--- /dev/null
+++ b/src/doc/grid_tests.cpp
@@ -0,0 +1,86 @@
+// Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gtest/gtest.h>
+
+#include "doc/grid.h"
+#include "gfx/rect_io.h"
+#include "gfx/region.h"
+
+// TODO add gfx/point_io.h and gfx/size_io.h
+namespace gfx {
+
+inline std::ostream& operator<<(std::ostream& os, const Point& pt) {
+  return os << "("
+            << pt.x << ", "
+            << pt.y << ")";
+}
+
+inline std::ostream& operator<<(std::ostream& os, const Size& sz) {
+  return os << "("
+            << sz.w << ", "
+            << sz.h << ")";
+}
+
+} // namespace gfx
+
+using namespace doc;
+using namespace gfx;
+
+TEST(Grid, Rect)
+{
+  auto grid = Grid::MakeRect(Size(16, 16));
+
+  EXPECT_EQ(Size(16, 16), grid.tileSize());
+  EXPECT_EQ(Point(16, 16), grid.tileOffset());
+
+  EXPECT_EQ(Point(16, 16), grid.tileToCanvas(Point(1, 1)));
+  EXPECT_EQ(Point(32, 16), grid.tileToCanvas(Point(2, 1)));
+  EXPECT_EQ(Point(0, 0), grid.canvasToTile(Point(5, 5)));
+  EXPECT_EQ(Point(1, 1), grid.canvasToTile(Point(16, 16)));
+  EXPECT_EQ(Rect(1, 0, 1, 2), grid.canvasToTile(Rect(16, 5, 16, 16)));
+
+  EXPECT_EQ(Rect(0, 0, 32, 32), grid.alignBounds(Rect(4, 5, 16, 17)));
+  EXPECT_EQ(Rect(16, 16, 16, 16), grid.alignBounds(Rect(16, 16, 16, 16)));
+  EXPECT_EQ(Rect(16, 16, 32, 16), grid.alignBounds(Rect(16, 16, 17, 16)));
+  EXPECT_EQ(Rect(16, 16, 48, 16), grid.alignBounds(Rect(17, 16, 32, 16)));
+
+  gfx::Region rgn;
+  rgn |= gfx::Region(gfx::Rect(5, 17, 8, 8));
+  rgn |= gfx::Region(gfx::Rect(17, 5, 16, 8));
+  auto pts = grid.tilesInCanvasRegion(rgn);
+  ASSERT_EQ(3, pts.size());
+  EXPECT_EQ(gfx::Point(1, 0), pts[0]);
+  EXPECT_EQ(gfx::Point(2, 0), pts[1]);
+  EXPECT_EQ(gfx::Point(0, 1), pts[2]);
+}
+
+TEST(Grid, RectWithOffset)
+{
+  auto grid = Grid::MakeRect(Size(16, 16));
+  grid.origin(gfx::Point(17, 16));
+
+  EXPECT_EQ(Point(0, 0), grid.canvasToTile(Point(17, 16)));
+  EXPECT_EQ(Point(0, 0), grid.canvasToTile(Point(17+15, 16)));
+  EXPECT_EQ(Point(1, 0), grid.canvasToTile(Point(17+16, 16)));
+
+  EXPECT_EQ(Point(-1, 0), grid.canvasToTile(Point(16, 16)));
+  EXPECT_EQ(Point(-1, 0), grid.canvasToTile(Point(2, 16)));
+  EXPECT_EQ(Point(-1, 0), grid.canvasToTile(Point(1, 16)));
+
+  grid.origin(gfx::Point(-1, -1));
+  EXPECT_EQ(Rect(1, 1, 1, 1), grid.canvasToTile(Rect(30, 30, 1, 1)));
+}
+
+int main(int argc, char** argv)
+{
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/src/doc/image.cpp b/src/doc/image.cpp
index dcfa8bf89..993a4482c 100644
--- a/src/doc/image.cpp
+++ b/src/doc/image.cpp
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2018 Igara Studio S.A.
+// Copyright (c) 2018-2019 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -61,6 +61,7 @@ Image* Image::create(const ImageSpec& spec,
     case ColorMode::GRAYSCALE: return new ImageImpl<GrayscaleTraits>(spec, buffer);
     case ColorMode::INDEXED:   return new ImageImpl<IndexedTraits>(spec, buffer);
     case ColorMode::BITMAP:    return new ImageImpl<BitmapTraits>(spec, buffer);
+    case ColorMode::TILEMAP:   return new ImageImpl<TilemapTraits>(spec, buffer);
   }
   return nullptr;
 }
diff --git a/src/doc/image.h b/src/doc/image.h
index c95587f99..d5da243f7 100644
--- a/src/doc/image.h
+++ b/src/doc/image.h
@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2018 Igara Studio S.A.
+// Copyright (c) 2018-2019 Igara Studio S.A.
 // Copyright (c) 2001-2016 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -107,6 +107,7 @@ namespace doc {
       case IMAGE_GRAYSCALE: return GrayscaleTraits::getRowStrideBytes(pixels_per_row);
       case IMAGE_INDEXED:   return IndexedTraits::getRowStrideBytes(pixels_per_row);
       case IMAGE_BITMAP:    return BitmapTraits::getRowStrideBytes(pixels_per_row);
+      case IMAGE_TILEMAP:   return TilemapTraits::getRowStrideBytes(pixels_per_row);
     }
     return 0;
   }
diff --git a/src/doc/image_io.cpp b/src/doc/image_io.cpp
index c8ab4f0fe..b229e4b27 100644
--- a/src/doc/image_io.cpp
+++ b/src/doc/image_io.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (C) 2019  Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -110,12 +111,14 @@ Image* read_image(std::istream& is, bool setId)
   if ((pixelFormat != IMAGE_RGB &&
        pixelFormat != IMAGE_GRAYSCALE &&
        pixelFormat != IMAGE_INDEXED &&
-       pixelFormat != IMAGE_BITMAP) ||
+       pixelFormat != IMAGE_BITMAP &&
+       pixelFormat != IMAGE_TILEMAP) ||
       (width < 1 || height < 1) ||
       (width > 0xfffff || height > 0xfffff))
     return nullptr;
 
-  std::unique_ptr<Image> image(Image::create(static_cast<PixelFormat>(pixelFormat), width, height));
+  std::unique_ptr<Image> image(
+    Image::create(static_cast<PixelFormat>(pixelFormat), width, height));
   int rowSize = image->getRowStrideSize();
 
 #if 0
diff --git a/src/doc/image_iterator.h b/src/doc/image_iterator.h
index 6d3a0fb8a..37b8b782f 100644
--- a/src/doc/image_iterator.h
+++ b/src/doc/image_iterator.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -379,6 +380,9 @@ namespace doc {
       return m_access;
     }
 
+    int x() const { return m_x; }
+    int y() const { return m_y; }
+
   private:
     Image* m_image;
     pointer m_ptr;
diff --git a/src/doc/image_traits.h b/src/doc/image_traits.h
index a56e91c2b..00fb6b3d5 100644
--- a/src/doc/image_traits.h
+++ b/src/doc/image_traits.h
@@ -158,6 +158,38 @@ namespace doc {
     }
   };
 
+  struct TilemapTraits {
+    static const ColorMode color_mode = ColorMode::TILEMAP;
+    static const PixelFormat pixel_format = IMAGE_TILEMAP;
+
+    enum {
+      bits_per_pixel = 32,
+      bytes_per_pixel = 4,
+      pixels_per_byte = 0,
+      channels = 3,             // Tile Index + Tile Set + Flags
+      has_alpha = false,
+    };
+
+    typedef uint32_t pixel_t;
+    typedef pixel_t* address_t;
+    typedef const pixel_t* const_address_t;
+
+    static const pixel_t min_value = 0x00000000l;
+    static const pixel_t max_value = 0xffffffffl;
+
+    static inline int getRowStrideBytes(int pixels_per_row) {
+      return bytes_per_pixel * pixels_per_row;
+    }
+
+    static inline BlendFunc get_blender(BlendMode blend_mode, bool newBlend) {
+      return get_indexed_blender(blend_mode, newBlend);
+    }
+
+    static inline bool same_color(const pixel_t a, const pixel_t b) {
+      return a == b;
+    }
+  };
+
 } // namespace doc
 
 #endif
diff --git a/src/doc/layer.cpp b/src/doc/layer.cpp
index cbd9a9fd2..1d9e4b9e0 100644
--- a/src/doc/layer.cpp
+++ b/src/doc/layer.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -28,7 +29,9 @@ Layer::Layer(ObjectType type, Sprite* sprite)
       int(LayerFlags::Visible) |
       int(LayerFlags::Editable)))
 {
-  ASSERT(type == ObjectType::LayerImage || type == ObjectType::LayerGroup);
+  ASSERT(type == ObjectType::LayerImage ||
+         type == ObjectType::LayerGroup ||
+         type == ObjectType::LayerTilemap);
 
   setName("Layer");
 }
@@ -184,13 +187,18 @@ Cel* Layer::cel(frame_t frame) const
 //////////////////////////////////////////////////////////////////////
 // LayerImage class
 
-LayerImage::LayerImage(Sprite* sprite)
-  : Layer(ObjectType::LayerImage, sprite)
+LayerImage::LayerImage(ObjectType type, Sprite* sprite)
+  : Layer(type, sprite)
   , m_blendmode(BlendMode::NORMAL)
   , m_opacity(255)
 {
 }
 
+LayerImage::LayerImage(Sprite* sprite)
+  : LayerImage(ObjectType::LayerImage, sprite)
+{
+}
+
 LayerImage::~LayerImage()
 {
   destroyAllCels();
@@ -297,7 +305,8 @@ void LayerImage::addCel(Cel* cel)
   ASSERT(cel->data() && "The cel doesn't contain CelData");
   ASSERT(cel->image());
   ASSERT(sprite());
-  ASSERT(cel->image()->pixelFormat() == sprite()->pixelFormat());
+  ASSERT(cel->image()->pixelFormat() == sprite()->pixelFormat() ||
+         cel->image()->pixelFormat() == IMAGE_TILEMAP);
 
   CelIterator it = findFirstCelIteratorAfter(cel->frame());
   m_cels.insert(it, cel);
diff --git a/src/doc/layer.h b/src/doc/layer.h
index ba886cb99..a1d9031d8 100644
--- a/src/doc/layer.h
+++ b/src/doc/layer.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -23,8 +24,8 @@ namespace doc {
   class Image;
   class Sprite;
   class Layer;
-  class LayerImage;
   class LayerGroup;
+  class LayerImage;
 
   //////////////////////////////////////////////////////////////////////
   // Layer class
@@ -72,8 +73,10 @@ namespace doc {
     Layer* getPreviousInWholeHierarchy() const;
     Layer* getNextInWholeHierarchy() const;
 
-    bool isImage() const { return type() == ObjectType::LayerImage; }
+    bool isImage() const { return (type() == ObjectType::LayerImage ||
+                                   type() == ObjectType::LayerTilemap); }
     bool isGroup() const { return type() == ObjectType::LayerGroup; }
+    bool isTilemap() const { return type() == ObjectType::LayerTilemap; }
     virtual bool isBrowsable() const { return false; }
 
     bool isBackground() const  { return hasFlags(LayerFlags::Background); }
@@ -135,6 +138,7 @@ namespace doc {
 
   class LayerImage : public Layer {
   public:
+    LayerImage(ObjectType type, Sprite* sprite);
     explicit LayerImage(Sprite* sprite);
     virtual ~LayerImage();
 
diff --git a/src/doc/layer_io.cpp b/src/doc/layer_io.cpp
index de4f86f6a..a57d9431d 100644
--- a/src/doc/layer_io.cpp
+++ b/src/doc/layer_io.cpp
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2018 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -18,6 +19,7 @@
 #include "doc/image_io.h"
 #include "doc/layer.h"
 #include "doc/layer_io.h"
+#include "doc/layer_tilemap.h"
 #include "doc/sprite.h"
 #include "doc/string_io.h"
 #include "doc/subobjects_io.h"
@@ -96,6 +98,12 @@ void write_layer(std::ostream& os, const Layer* layer)
       break;
     }
 
+    case ObjectType::LayerTilemap: {
+      // Tileset index
+      write32(os, static_cast<const LayerTilemap*>(layer)->tilesetIndex());
+      break;
+    }
+
   }
 
   write_user_data(os, layer->userData());
@@ -148,7 +156,7 @@ Layer* read_layer(std::istream& is, SubObjectsFromSprite* subObjects)
     }
 
     case ObjectType::LayerGroup: {
-      // Create the layer set
+      // Create the layer group
       layer.reset(new LayerGroup(subObjects->sprite()));
 
       // Number of sub-layers
@@ -163,6 +171,13 @@ Layer* read_layer(std::istream& is, SubObjectsFromSprite* subObjects)
       break;
     }
 
+    case ObjectType::LayerTilemap: {
+      // Create the layer tilemap
+      doc::tileset_index tsi = read32(is); // Tileset index
+      layer.reset(new LayerTilemap(subObjects->sprite(), tsi));
+      break;
+    }
+
     default:
       throw InvalidLayerType("Invalid layer type found in stream");
 
diff --git a/src/doc/layer_tilemap.cpp b/src/doc/layer_tilemap.cpp
new file mode 100644
index 000000000..e8ce535b8
--- /dev/null
+++ b/src/doc/layer_tilemap.cpp
@@ -0,0 +1,31 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/layer_tilemap.h"
+
+#include "doc/primitives.h"
+#include "doc/sprite.h"
+#include "doc/tilesets.h"
+
+namespace doc {
+
+LayerTilemap::LayerTilemap(Sprite* sprite, const tileset_index tsi)
+  : LayerImage(ObjectType::LayerTilemap, sprite)
+  , m_tileset(sprite->tilesets()->get(tsi))
+  , m_tilesetIndex(tsi)
+{
+  ASSERT(m_tileset);
+}
+
+LayerTilemap::~LayerTilemap()
+{
+}
+
+} // namespace doc
diff --git a/src/doc/layer_tilemap.h b/src/doc/layer_tilemap.h
new file mode 100644
index 000000000..3fdfb299d
--- /dev/null
+++ b/src/doc/layer_tilemap.h
@@ -0,0 +1,35 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_LAYER_TILEMAP_H_INCLUDED
+#define DOC_LAYER_TILEMAP_H_INCLUDED
+#pragma once
+
+#include "doc/layer.h"
+#include "doc/tile.h"
+#include "doc/tileset.h"
+
+namespace doc {
+
+  class LayerTilemap : public LayerImage {
+  public:
+    explicit LayerTilemap(Sprite* sprite, const tileset_index tsi);
+    ~LayerTilemap();
+
+    // Returns the tileset of this layer. New automatically-created
+    // tiles should be stored into this tileset, and all tiles in the
+    // layer should share the same Grid spec.
+    Tileset* tileset() const { return m_tileset; }
+    tileset_index tilesetIndex() const { return m_tilesetIndex; }
+
+  private:
+    Tileset* m_tileset;
+    tileset_index m_tilesetIndex;
+  };
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/object_type.h b/src/doc/object_type.h
index 31f897375..4d1fc2b9c 100644
--- a/src/doc/object_type.h
+++ b/src/doc/object_type.h
@@ -22,10 +22,13 @@ namespace doc {
     CelData,
     LayerImage,
     LayerGroup,
+    LayerTilemap,
     Sprite,
     Document,
     Tag,
     Slice,
+    Tileset,
+    Tilesets,
   };
 
 } // namespace doc
diff --git a/src/doc/pixel_format.h b/src/doc/pixel_format.h
index f15819e21..3cb46fed2 100644
--- a/src/doc/pixel_format.h
+++ b/src/doc/pixel_format.h
@@ -1,4 +1,5 @@
 // Aseprite Document Library
+// Copyright (c) 2019 Igara Studio S.A.
 // Copyright (c) 2001-2014 David Capello
 //
 // This file is released under the terms of the MIT license.
@@ -11,10 +12,11 @@
 namespace doc {
 
   enum PixelFormat {
-    IMAGE_RGB,
-    IMAGE_GRAYSCALE,
-    IMAGE_INDEXED,
-    IMAGE_BITMAP
+    IMAGE_RGB,           // 32bpp see doc::rgba()
+    IMAGE_GRAYSCALE,     // 16bpp see doc::graya()
+    IMAGE_INDEXED,       // 8bpp
+    IMAGE_BITMAP,        // 1bpp
+    IMAGE_TILEMAP,       // 32bpp see doc::tile()
   };
 
 } // namespace doc
diff --git a/src/doc/primitives.cpp b/src/doc/primitives.cpp
index 80b7037d3..cf9ce05e2 100644
--- a/src/doc/primitives.cpp
+++ b/src/doc/primitives.cpp
@@ -17,6 +17,7 @@
 #include "doc/palette.h"
 #include "doc/remap.h"
 #include "doc/rgbmap.h"
+#include "gfx/region.h"
 
 #include <stdexcept>
 
@@ -63,6 +64,12 @@ void copy_image(Image* dst, const Image* src, int x, int y)
   dst->copy(src, gfx::Clip(x, y, 0, 0, src->width(), src->height()));
 }
 
+void copy_image(Image* dst, const Image* src, const gfx::Region& rgn)
+{
+  for (const gfx::Rect& rc : rgn)
+    dst->copy(src, gfx::Clip(rc));
+}
+
 Image* crop_image(const Image* image, int x, int y, int w, int h, color_t bg, const ImageBufferPtr& buffer)
 {
   ASSERT(image);
@@ -353,6 +360,7 @@ bool is_plain_image(const Image* img, color_t c)
     case IMAGE_GRAYSCALE: return is_plain_image_templ<GrayscaleTraits>(img, c);
     case IMAGE_INDEXED:   return is_plain_image_templ<IndexedTraits>(img, c);
     case IMAGE_BITMAP:    return is_plain_image_templ<BitmapTraits>(img, c);
+    case IMAGE_TILEMAP:   return is_plain_image_templ<TilemapTraits>(img, c);
   }
   return false;
 }
@@ -377,6 +385,7 @@ int count_diff_between_images(const Image* i1, const Image* i2)
     case IMAGE_GRAYSCALE: return count_diff_between_images_templ<GrayscaleTraits>(i1, i2);
     case IMAGE_INDEXED:   return count_diff_between_images_templ<IndexedTraits>(i1, i2);
     case IMAGE_BITMAP:    return count_diff_between_images_templ<BitmapTraits>(i1, i2);
+    case IMAGE_TILEMAP:   return count_diff_between_images_templ<TilemapTraits>(i1, i2);
   }
 
   ASSERT(false);
@@ -395,6 +404,7 @@ bool is_same_image(const Image* i1, const Image* i2)
     case IMAGE_GRAYSCALE: return is_same_image_templ<GrayscaleTraits>(i1, i2);
     case IMAGE_INDEXED:   return is_same_image_templ<IndexedTraits>(i1, i2);
     case IMAGE_BITMAP:    return is_same_image_templ<BitmapTraits>(i1, i2);
+    case IMAGE_TILEMAP:   return is_same_image_templ<TilemapTraits>(i1, i2);
   }
 
   ASSERT(false);
diff --git a/src/doc/primitives.h b/src/doc/primitives.h
index fb000c8c5..639c7f792 100644
--- a/src/doc/primitives.h
+++ b/src/doc/primitives.h
@@ -27,6 +27,7 @@ namespace doc {
 
   void copy_image(Image* dst, const Image* src);
   void copy_image(Image* dst, const Image* src, int x, int y);
+  void copy_image(Image* dst, const Image* src, const gfx::Region& rgn);
   Image* crop_image(const Image* image, int x, int y, int w, int h, color_t bg, const ImageBufferPtr& buffer = ImageBufferPtr());
   Image* crop_image(const Image* image, const gfx::Rect& bounds, color_t bg, const ImageBufferPtr& buffer = ImageBufferPtr());
   void rotate_image(const Image* src, Image* dst, int angle);
diff --git a/src/doc/sprite.cpp b/src/doc/sprite.cpp
index 5fa9139c3..6d1b2a6e7 100644
--- a/src/doc/sprite.cpp
+++ b/src/doc/sprite.cpp
@@ -23,6 +23,7 @@
 #include "doc/remap.h"
 #include "doc/rgbmap.h"
 #include "doc/tag.h"
+#include "doc/tilesets.h"
 
 #include <algorithm>
 #include <cstring>
@@ -61,6 +62,7 @@ Sprite::Sprite(const ImageSpec& spec,
   , m_rgbMap(nullptr)           // Initial RGB map
   , m_tags(this)
   , m_slices(this)
+  , m_tilesets(nullptr)
 {
   // Generate palette
   switch (spec.colorMode()) {
@@ -91,6 +93,9 @@ Sprite::~Sprite()
   // Destroy layers
   delete m_root;
 
+  // Destroy tilesets
+  delete m_tilesets;
+
   // Destroy palettes
   {
     PalettesList::iterator end = m_palettes.end();
@@ -467,7 +472,7 @@ void Sprite::replaceImage(ObjectId curImageId, const ImageRef& newImage)
 {
   for (Cel* cel : cels()) {
     if (cel->image()->id() == curImageId)
-      cel->data()->setImage(newImage);
+      cel->data()->setImage(newImage, cel->layer());
   }
 }
 
@@ -506,8 +511,6 @@ void Sprite::pickCels(const double x,
 
   for (int i=(int)layers.size()-1; i>=0; --i) {
     const Layer* layer = layers[i];
-    if (!layer->isImage())
-      continue;
 
     Cel* cel = layer->cel(frame);
     if (!cel)
@@ -611,4 +614,14 @@ CelsRange Sprite::uniqueCels(const SelectedFrames& selFrames) const
   return CelsRange(this, selFrames, CelsRange::UNIQUE);
 }
 
+////////////////////////////////////////
+// Tilesets
+
+Tilesets* Sprite::tilesets() const
+{
+  if (!m_tilesets)
+    m_tilesets = new Tilesets;
+  return m_tilesets;
+}
+
 } // namespace doc
diff --git a/src/doc/sprite.h b/src/doc/sprite.h
index 1e6915676..6cc1f60e3 100644
--- a/src/doc/sprite.h
+++ b/src/doc/sprite.h
@@ -43,6 +43,7 @@ namespace doc {
   class Remap;
   class RgbMap;
   class SelectedFrames;
+  class Tilesets;
 
   typedef std::vector<Palette*> PalettesList;
 
@@ -188,6 +189,11 @@ namespace doc {
     CelsRange uniqueCels() const;
     CelsRange uniqueCels(const SelectedFrames& selFrames) const;
 
+    ////////////////////////////////////////
+    // Tilesets
+
+    Tilesets* tilesets() const;
+
   private:
     Document* m_document;
     ImageSpec m_spec;
@@ -204,6 +210,9 @@ namespace doc {
     Tags m_tags;
     Slices m_slices;
 
+    // Tilesets
+    mutable Tilesets* m_tilesets;
+
     // Disable default constructor and copying
     Sprite();
     DISABLE_COPYING(Sprite);
diff --git a/src/doc/tile.h b/src/doc/tile.h
new file mode 100644
index 000000000..0a128cf98
--- /dev/null
+++ b/src/doc/tile.h
@@ -0,0 +1,44 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_TILE_H_INCLUDED
+#define DOC_TILE_H_INCLUDED
+#pragma once
+
+#include "base/ints.h"
+
+namespace doc {
+
+  typedef uint32_t tile_t;      // Same as color_t
+  typedef uint32_t tile_index;
+  typedef uint32_t tileset_index;
+  typedef uint32_t tile_flags;
+
+  const uint32_t tile_i_shift = 0;  // Tile index
+  const uint32_t tile_f_shift = 28; // Flags (flip, rotation)
+
+  const uint32_t tile_i_mask  = 0x1fffffff;
+  const uint32_t tile_f_mask  = 0xe0000000; // 3 flags
+  const uint32_t tile_f_flipx = 0x20000000;
+  const uint32_t tile_f_flipy = 0x40000000;
+  const uint32_t tile_f_90cw  = 0x80000000;
+
+  inline tile_index tile_geti(const tile_t t) {
+    return ((t & tile_i_mask) >> tile_i_shift);
+  }
+
+  inline tile_flags tile_getf(const tile_t t) {
+    return (t & tile_f_mask);
+  }
+
+  inline tile_t tile(const tile_index i, const tile_flags f) {
+    return (((i << tile_i_shift) & tile_i_mask) |
+            (f & tile_f_mask));
+  }
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/tileset.cpp b/src/doc/tileset.cpp
new file mode 100644
index 000000000..d9df3b91b
--- /dev/null
+++ b/src/doc/tileset.cpp
@@ -0,0 +1,45 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/tileset.h"
+
+namespace doc {
+
+Tileset::Tileset(Sprite* sprite,
+                 const Grid& grid,
+                 const tileset_index ntiles)
+  : Object(ObjectType::Tileset)
+  , m_sprite(sprite)
+  , m_grid(grid)
+  , m_tiles(ntiles)
+{
+}
+
+void Tileset::setOrigin(const gfx::Point& pt)
+{
+  m_grid.origin(pt);
+}
+
+int Tileset::getMemSize() const
+{
+  int size = sizeof(Tileset) + m_name.size();
+  for (auto& img : const_cast<Tileset*>(this)->m_tiles) {
+    if (img)
+      size += img->getMemSize();
+  }
+  return size;
+}
+
+void Tileset::resize(const tile_index ntiles)
+{
+  m_tiles.resize(ntiles);
+}
+
+} // namespace doc
diff --git a/src/doc/tileset.h b/src/doc/tileset.h
new file mode 100644
index 000000000..d0f0ec63d
--- /dev/null
+++ b/src/doc/tileset.h
@@ -0,0 +1,76 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_TILESET_H_INCLUDED
+#define DOC_TILESET_H_INCLUDED
+#pragma once
+
+#include "doc/grid.h"
+#include "doc/image_ref.h"
+#include "doc/object.h"
+#include "doc/tile.h"
+
+#include <string>
+#include <vector>
+
+namespace doc {
+
+  class Sprite;
+
+  class Tileset : public Object {
+  public:
+    typedef std::vector<ImageRef> Tiles;
+    typedef Tiles::iterator iterator;
+
+    Tileset(Sprite* sprite,
+            const Grid& grid,
+            const tileset_index ntiles);
+
+    Sprite* sprite() const { return m_sprite; }
+    const Grid& grid() const { return m_grid; }
+    void setOrigin(const gfx::Point& pt);
+
+    const std::string& name() const { return m_name; }
+    void setName(const std::string& name) { m_name = name; }
+
+    int getMemSize() const override;
+
+    iterator begin() { return m_tiles.begin(); }
+    iterator end() { return m_tiles.end(); }
+    tile_index size() const { return tile_index(m_tiles.size()); }
+    void resize(const tile_index ntiles);
+
+    ImageRef get(const tile_index index) const {
+      if (index < size())
+        return m_tiles[index];
+      else
+        return ImageRef(nullptr);
+    }
+
+    void set(const tile_index index, ImageRef& image) {
+      m_tiles[index] = image;
+    }
+
+    tile_index add(const ImageRef& image) {
+      m_tiles.push_back(image);
+      return tile_t(m_tiles.size()-1);
+    }
+
+    void erase(const tile_index ti) {
+      ASSERT(ti >= 0 && ti < size());
+      m_tiles.erase(m_tiles.begin()+ti);
+    }
+
+  private:
+    Sprite* m_sprite;
+    Grid m_grid;
+    Tiles m_tiles;
+    std::string m_name;
+  };
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/tileset_hash_table.h b/src/doc/tileset_hash_table.h
new file mode 100644
index 000000000..22122d981
--- /dev/null
+++ b/src/doc/tileset_hash_table.h
@@ -0,0 +1,29 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_TILESET_HASH_TABLE_H_INCLUDED
+#define DOC_TILESET_HASH_TABLE_H_INCLUDED
+#pragma once
+
+#include "doc/image.h"
+#include "doc/image_ref.h"
+#include "doc/images_map.h"
+#include "doc/primitives.h"
+#include "doc/tile.h"
+
+#include <unordered_map>
+
+namespace doc {
+
+  // A hash table used to match Image pixels data <-> tileset index
+  typedef std::unordered_map<ImageRef,
+                             tile_index,
+                             details::image_hash,
+                             details::image_eq> TilesetHashTable;
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/tileset_io.cpp b/src/doc/tileset_io.cpp
new file mode 100644
index 000000000..861c2e651
--- /dev/null
+++ b/src/doc/tileset_io.cpp
@@ -0,0 +1,49 @@
+// Aseprite Document Library
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/tileset_io.h"
+
+#include "base/serialization.h"
+#include "doc/grid_io.h"
+#include "doc/subobjects_io.h"
+#include "doc/tileset.h"
+
+#include <iostream>
+
+namespace doc {
+
+using namespace base::serialization;
+using namespace base::serialization::little_endian;
+
+bool write_tileset(std::ostream& os,
+                   const Tileset* tileset,
+                   CancelIO* cancel)
+{
+  write32(os, tileset->id());
+  write32(os, tileset->size());
+  return write_grid(os, tileset->grid());
+
+  // TODO save images
+}
+
+Tileset* read_tileset(std::istream& is,
+                      SubObjectsFromSprite* subObjects,
+                      bool setId)
+{
+  ObjectId id = read32(is);
+  tileset_index ntiles = read32(is);
+  Grid grid = read_grid(is, setId);
+  auto tileset = new Tileset(subObjects->sprite(), grid, ntiles);
+  if (setId)
+    tileset->setId(id);
+  return tileset;
+}
+
+}
diff --git a/src/doc/tileset_io.h b/src/doc/tileset_io.h
new file mode 100644
index 000000000..7b44f3380
--- /dev/null
+++ b/src/doc/tileset_io.h
@@ -0,0 +1,29 @@
+// Aseprite Document Library
+// Copyright (C) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_TILESET_IO_H_INCLUDED
+#define DOC_TILESET_IO_H_INCLUDED
+#pragma once
+
+#include <iosfwd>
+
+namespace doc {
+
+  class CancelIO;
+  class SubObjectsFromSprite;
+  class Tileset;
+
+  bool write_tileset(std::ostream& os,
+                     const Tileset* tileset,
+                     CancelIO* cancel = nullptr);
+
+  Tileset* read_tileset(std::istream& is,
+                        SubObjectsFromSprite* subObjects,
+                        bool setId = true);
+
+} // namespace doc
+
+#endif
diff --git a/src/doc/tilesets.cpp b/src/doc/tilesets.cpp
new file mode 100644
index 000000000..2a3ad4fe3
--- /dev/null
+++ b/src/doc/tilesets.cpp
@@ -0,0 +1,42 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "doc/tilesets.h"
+
+namespace doc {
+
+Tilesets::Tilesets()
+  : Object(ObjectType::Tilesets)
+{
+}
+
+Tilesets::~Tilesets()
+{
+  for (auto tileset : m_tilesets)
+    delete tileset;
+}
+
+int Tilesets::getMemSize() const
+{
+  int size = sizeof(Tilesets);
+  for (auto tileset : m_tilesets) {
+    if (tileset)
+      size += tileset->getMemSize();
+  }
+  return size;
+}
+
+tileset_index Tilesets::add(Tileset* tileset)
+{
+  m_tilesets.push_back(tileset);
+  return tileset_index(m_tilesets.size()-1);
+}
+
+} // namespace doc
diff --git a/src/doc/tilesets.h b/src/doc/tilesets.h
new file mode 100644
index 000000000..65d53b37d
--- /dev/null
+++ b/src/doc/tilesets.h
@@ -0,0 +1,64 @@
+// Aseprite Document Library
+// Copyright (c) 2019  Igara Studio S.A.
+//
+// This file is released under the terms of the MIT license.
+// Read LICENSE.txt for more information.
+
+#ifndef DOC_TILESETS_H_INCLUDED
+#define DOC_TILESETS_H_INCLUDED
+#pragma once
+
+#include "doc/tileset.h"
+
+#include <vector>
+
+namespace doc {
+
+  class Tilesets : public Object {
+  public:
+    typedef std::vector<Tileset*> Array;
+    typedef Array::iterator iterator;
+    typedef Array::const_iterator const_iterator;
+
+    Tilesets();
+    ~Tilesets();
+
+    int getMemSize() const override;
+
+    iterator begin() { return m_tilesets.begin(); }
+    iterator end() { return m_tilesets.end(); }
+    const_iterator begin() const { return m_tilesets.begin(); }
+    const_iterator end() const { return m_tilesets.end(); }
+    tileset_index size() const { return (tileset_index)m_tilesets.size(); }
+
+    tileset_index add(Tileset* tileset);
+
+    Tileset* get(const tileset_index tsi) {
+      if (tsi < size())
+        return m_tilesets[tsi];
+      else
+        return nullptr;
+    }
+
+    void set(const tileset_index tsi, Tileset* tileset) {
+      if (tsi >= m_tilesets.size())
+        m_tilesets.resize(tsi+1, nullptr);
+      m_tilesets[tsi] = tileset;
+    }
+
+    void erase(const tileset_index tsi) {
+      // Do not m_tilesets.erase() the tileset so other tilesets
+      // indexes/IDs are kept intact.
+      if (tsi == size()-1)
+        m_tilesets.erase(--m_tilesets.end());
+      else
+        m_tilesets[tsi] = nullptr;
+    }
+
+  private:
+    Array m_tilesets;
+  };
+
+} // namespace doc
+
+#endif
diff --git a/src/render/render.cpp b/src/render/render.cpp
index d8cbcada2..452ab97b6 100644
--- a/src/render/render.cpp
+++ b/src/render/render.cpp
@@ -17,11 +17,16 @@
 #include "doc/doc.h"
 #include "doc/handle_anidir.h"
 #include "doc/image_impl.h"
+#include "doc/layer_tilemap.h"
+#include "doc/tileset.h"
+#include "doc/tilesets.h"
 #include "gfx/clip.h"
 #include "gfx/region.h"
 
 #include <cmath>
 
+#define TRACE_RENDER_CEL(...)
+
 namespace render {
 
 namespace {
@@ -1042,7 +1047,8 @@ void Render::renderLayer(
 
   switch (layer->type()) {
 
-    case ObjectType::LayerImage: {
+    case ObjectType::LayerImage:
+    case ObjectType::LayerTilemap: {
       if ((!render_background  &&  layer->isBackground()) ||
           (!render_transparent && !layer->isBackground()))
         break;
@@ -1084,8 +1090,6 @@ void Render::renderLayer(
                                  m_previewPos.y,
                                  m_previewImage->width(),
                                  m_previewImage->height());
-
-          ASSERT(celImage->pixelFormat() == cel->image()->pixelFormat());
         }
         else {
           celImage = cel->image();
@@ -1115,8 +1119,6 @@ void Render::renderLayer(
           if (!isSelected && m_nonactiveLayersOpacity != 255)
             opacity = MUL_UN8(opacity, m_nonactiveLayersOpacity, t);
 
-          ASSERT(celImage->maskColor() == m_sprite->transparentColor());
-
           // Draw parts outside the "m_extraCel" area
           if (drawExtra && m_extraType == ExtraType::PATCH) {
             gfx::Region originalAreas(area.srcBounds());
@@ -1125,16 +1127,16 @@ void Render::renderLayer(
 
             for (auto rc : originalAreas) {
               renderCel(
-                image, celImage, pal, celBounds,
+                image, celImage, layer, pal, celBounds,
                 gfx::Clip(area.dst.x+rc.x-area.src.x,
-                          area.dst.y+rc.y-area.src.y, rc), compositeImage,
-                opacity, layerBlendMode);
+                          area.dst.y+rc.y-area.src.y, rc),
+                compositeImage, opacity, layerBlendMode);
             }
           }
           // Draw the whole cel
           else {
             renderCel(
-              image, celImage, pal,
+              image, celImage, layer, pal,
               celBounds, area, compositeImage,
               opacity, layerBlendMode);
           }
@@ -1164,6 +1166,7 @@ void Render::renderLayer(
     if (m_extraCel->opacity() > 0) {
       renderCel(
         image, m_extraImage,
+        nullptr,                // Without layer
         m_sprite->palette(frame),
         m_extraCel->bounds(),
         gfx::Clip(area.dst.x+extraArea.x-area.src.x,
@@ -1199,6 +1202,7 @@ void Render::renderCel(
   renderCel(
     dst_image,
     cel_image,
+    cel_layer,
     pal,
     celBounds,
     area,
@@ -1210,6 +1214,7 @@ void Render::renderCel(
 void Render::renderCel(
   Image* dst_image,
   const Image* cel_image,
+  const Layer* cel_layer,
   const Palette* pal,
   const gfx::RectF& celBounds,
   const gfx::Clip& area,
@@ -1217,14 +1222,56 @@ void Render::renderCel(
   const int opacity,
   const BlendMode blendMode)
 {
-  renderImage(dst_image,
-              cel_image,
-              pal,
-              celBounds,
-              area,
-              compositeImage,
-              opacity,
-              blendMode);
+  TRACE_RENDER_CEL("dstImage=(%d %d) celImage=(%d %d) celBounds=(%d %d %d %d) clipArea=(src=%d %d dst=%d %d %d %d)\n",
+                   dst_image->width(), dst_image->height(),
+                   cel_image->width(), cel_image->height(),
+                   int(celBounds.x), int(celBounds.y),
+                   int(celBounds.w), int(celBounds.h),
+                   area.src.x, area.src.y, area.dst.x, area.dst.y, area.size.w, area.size.h);
+
+  if (cel_layer &&
+      cel_image->pixelFormat() == IMAGE_TILEMAP) {
+    ASSERT(cel_layer->isTilemap());
+
+    auto tilemapLayer = static_cast<const LayerTilemap*>(cel_layer);
+    doc::Grid grid = tilemapLayer->tileset()->grid();
+    grid.origin(grid.origin() + gfx::Point(celBounds.origin()));
+
+    const Tileset* tileset = tilemapLayer->tileset();
+    ASSERT(tileset);
+    if (!tileset)
+      return;
+
+    gfx::Rect tilesToDraw = grid.canvasToTile(gfx::Rect(area.src, area.size));
+    tilesToDraw &= cel_image->bounds();
+    TRACE_RENDER_CEL("Drawing tilemap (%d %d %d %d)\n",
+                     tilesToDraw.x, tilesToDraw.y, tilesToDraw.w, tilesToDraw.h);
+
+    for (int v=tilesToDraw.y; v<tilesToDraw.y2(); ++v) {
+      for (int u=tilesToDraw.x; u<tilesToDraw.x2(); ++u) {
+        auto tileBoundsOnCanvas = grid.tileToCanvas(gfx::Rect(u, v, 1, 1));
+        TRACE_RENDER_CEL(" - tile (%d %d) -> (%d %d %d %d)\n", u, v,
+                         tileBoundsOnCanvas.x, tileBoundsOnCanvas.y,
+                         tileBoundsOnCanvas.w, tileBoundsOnCanvas.h);
+        if (!cel_image->bounds().contains(u, v))
+          continue;
+
+        const tile_t t = cel_image->getPixel(u, v);
+        const tile_index i = tile_geti(t);
+
+        const ImageRef tile_image = tileset->get(i);
+        if (!tile_image)
+          continue;
+
+        renderImage(dst_image, tile_image.get(), pal, tileBoundsOnCanvas,
+                    area, compositeImage, opacity, blendMode);
+      }
+    }
+  }
+  else {
+    renderImage(dst_image, cel_image, pal, celBounds,
+                area, compositeImage, opacity, blendMode);
+  }
 }
 
 void Render::renderImage(
diff --git a/src/render/render.h b/src/render/render.h
index fc397cfe3..9641f98bf 100644
--- a/src/render/render.h
+++ b/src/render/render.h
@@ -178,6 +178,7 @@ namespace render {
     void renderCel(
       Image* dst_image,
       const Image* cel_image,
+      const Layer* cel_layer,
       const Palette* pal,
       const gfx::RectF& celBounds,
       const gfx::Clip& area,