Update INSTALL.md with information about the Skia back-end

INSTALL.md

@@ -1,12 +1,23 @@
+# Table of contents
+
+* [Platforms](#platforms)
+* [Get the source code](#get-the-source-code)
+* [Dependencies](#dependencies)
+  * [Linux dependencies](#linux-dependencies)
+* [Compiling](#compiling)
+* [Mac OS X details](#mac-os-x-details)
+  * [Issues with Retina displays](#issues-with-retina-displays)
+* [Using shared third party libraries](#using-shared-third-party-libraries)
+  * [Linux issues](#linux-issues)
+
 # Platforms
 
 You should be able to compile Aseprite successfully on the following
 platforms:
 
-* Windows + VS2013 + DirectX SDK
+* Windows 10 + VS2015 Community Edition + Windows 10 SDK
-* Mac OS X 10.8 Mountain Lion + Xcode 5.1.1 + Mac OS X 10.4 SDK universal
+* Mac OS X 10.11.4 El Capitan + Xcode 7.3 + OS X 10.11 SDK + Skia (without GPU)
-* Linux + gcc with some C++11 support, this port is not compiled
+* Linux + gcc 4.8 with some C++11 support
-  regularly so you can expect some errors in the master branch.
 
 # Get the source code
 
@@ -28,13 +39,39 @@ To update an existing copy:
 On Windows you can use programs like
 [msysgit](http://msysgit.github.io/) to clone the repository.
 
-# Compiling
+# Dependencies
 
 Aseprite uses the latest version of [CMake](http://www.cmake.org/)
-(3.0) as its build system. You will not need any extra library
+(3.0 or greater) as its build system. Also we use
-because the repository already contains the source code of all
+[Ninja](https://ninja-build.org) build files regularly instead of
-dependencies, even a modified version of the Allegro library is
+Visual Studio or Xcode projects.
-included in master branch.
+
+Aseprite can be compiled with two different back-ends:
+
+1. Allegro back-end (Windows, Linux): You will not need any extra
+   library because the repository already contains a modified version
+   of the Allegro library. This back-end is only available for Windows
+   and Linux and it'll be removed in following versions.
+
+2. Skia back-end (Windows, OS X): You will need a compiled version of
+   [Skia](http://skia.org/), `chrome/m50` branch, without GPU support,
+   i.e.  compiled with `GYP_DEFINES='skia_gpu=0'`. When you compile
+   Aseprite, you'll need to give some variables to CMake:
+   `-DUSE_SKIA_ALLEG4=OFF`, `-DUSE_SKIA_BACKEND=ON`, and
+   `-DSKIA_DIR=...` pointing to the Skia checkout directory. (Note:
+   The GPU support is a work-in-progress, so next versions .)
+
+## Linux dependencies
+
+You will need the following dependencies:
+
+    sudo apt-get update -qq
+    sudo apt-get install -y g++ libx11-dev libxcursor-dev cmake ninja-build
+
+The `libxcursor-dev` package is needed to
+[hide the hardware cursor](https://github.com/aseprite/aseprite/issues/913).
+
+# Compiling
 
 The following are the steps to compile Aseprite (in this case we have
 the repository clone in a directory called `aseprite`):
@@ -42,8 +79,8 @@ the repository clone in a directory called `aseprite`):
 1. Make a build directory to leave all the files that are result of
    the compilation process (`.exe`, `.lib`, `.obj`, `.a`, `.o`, etc).
 
-        C:\...\>cd aseprite
+        C:\>cd aseprite
-        C:\...\aseprite>mkdir build
+        C:\aseprite>mkdir build
 
    In this way, if you want to start with a fresh copy of Aseprite
    source code, you can remove the `build` directory and start again.
@@ -51,26 +88,30 @@ the repository clone in a directory called `aseprite`):
 2. Enter in the new directory and execute cmake giving to it
    your compiler as generator:
 
-        C:\...\aseprite>cd build
+        C:\aseprite>cd build
+
+   If you have ninja:
+
+        C:\aseprite\build>cmake -G Ninja ..
 
    If you have nmake (MSVC compilers):
 
-        C:\...\aseprite\build>cmake -G "NMake Makefiles" ..
+        C:\aseprite\build>cmake -G "NMake Makefiles" ..
 
    If you have Visual Studio you can generate a solution:
 
-        C:\...\aseprite\build>cmake -G "Visual Studio 12 2013" ..
+        C:\aseprite\build>cmake -G "Visual Studio 12 2013" ..
 
    If you are on Linux:
 
-        /.../aseprite/build$ cmake -G "Unix Makefiles" ..
+        ~/aseprite/build$ cmake -G "Unix Makefiles" ..
 
    For more information in [CMake wiki](http://www.vtk.org/Wiki/CMake_Generator_Specific_Information).
 
    Additionally you can change build settings by passing them on the
    command line, like so:
 
-        /.../aseprite/build$ cmake -DCMAKE_INSTALL_PREFIX=~/software ..
+        ~/aseprite/build$ cmake -DCMAKE_INSTALL_PREFIX=~/software ..
 
    or later on with a tool like
    [`ccmake`](https://cmake.org/cmake/help/latest/manual/ccmake.1.html)
@@ -86,31 +127,7 @@ the repository clone in a directory called `aseprite`):
    will be copied to an appropriate location
    (e.g. `/usr/local/bin/aseprite` on Linux).
 
-## Linux details
+# Mac OS X details
-
-You will need the following dependencies:
-
-    sudo apt-get update -qq
-    sudo apt-get install -y g++ libx11-dev libxcursor-dev cmake ninja-build
-
-The `libxcursor-dev` package is needed to
-[hide the hardware cursor](https://github.com/aseprite/aseprite/issues/913).
-
-### Known issues
-
-If you use the official version of Allegro 4.4 library (i.e. you
-compile with `USE_SHARED_ALLEGRO4=ON`) you will experience a couple of
-known issues solved in
-[our patched version of Allegro 4.4 library](https://github.com/aseprite/aseprite/tree/master/src/allegro):
-
-* You will
-  [not be able to resize the window](https://github.com/aseprite/aseprite/issues/192)
-  ([patch](https://github.com/aseprite/aseprite/commit/920f6275d55113507121afcbcda80adb44cc0563)).
-* You will have problems
-  [adding HSV colors in non-English systems](https://github.com/aseprite/aseprite/commit/27b55030e26e93c5e8d9e7e21206c8709d46ff22)
-  using the warning icon.
-
-## Mac OS X details
 
 You need the old Mac OS X 10.4 SDK universal, which can be obtained
 from Xcode 3.1 Developer Tools (Xcode 3.1 Developer DVD,
@@ -128,7 +145,7 @@ cmake with the following parameters:
     -DCMAKE_OSX_SYSROOT:STRING=/SDKs/MacOSX10.4u.sdk
     -DWITH_HarfBuzz=OFF
 
-### Issues with Retina displays
+## Issues with Retina displays
 
 If you have a Retina display, check this issue:
 
@@ -144,8 +161,16 @@ After running `cmake -G`, you can edit `build/CMakeCache.txt` file,
 and enable the `USE_SHARED_` flag (set its value to `ON`) of the
 library that you want to be linked dynamically.
 
-# Profiling
+## Linux issues
 
-You must compile with `Profile` configuration. For example on Linux:
+If you use the official version of Allegro 4.4 library (i.e. you
+compile with `USE_SHARED_ALLEGRO4=ON`) you will experience a couple of
+known issues solved in
+[our patched version of Allegro 4.4 library](https://github.com/aseprite/aseprite/tree/master/src/allegro):
 
-    /.../aseprite/build$ cmake .. -G "Unix Makefiles" -DCMAKE_BUILD_TYPE:STRING=Profile -DCOMPILER_GCC:BOOL=ON
+* You will
+  [not be able to resize the window](https://github.com/aseprite/aseprite/issues/192)
+  ([patch](https://github.com/aseprite/aseprite/commit/920f6275d55113507121afcbcda80adb44cc0563)).
+* You will have problems
+  [adding HSV colors in non-English systems](https://github.com/aseprite/aseprite/commit/27b55030e26e93c5e8d9e7e21206c8709d46ff22)
+  using the warning icon.