aseprite/docs/ase-file-specs.md
David Capello 14ba0ab411 Add addition/subtract/divide blending modes
Changes:
* Added SeparatorInView() to add separators inside a ListBox or ComboBox.
* Added BlendModeItem() to represent each item in the blending modes
  ComboBox.
* Now a ComboBox can contain any kind of widgets as children (not just
  ListItem). This is required to add separators in the blending modes
  ComboBox.

Feature request:
https://community.aseprite.org/t/additive-blending-feature/121
2017-07-24 15:25:13 -03:00

12 KiB

Aseprite File Format (.ase/.aseprite) Specifications

Copyright (C) 2001-2017 by David Capello

  1. References

  2. Introduction

  3. Header

  4. Frames

  5. Chunk Types

  6. File Format Changes

  7. References


ASE files use Intel (little-endian) byte order.

Data Type Details
BYTE An 8-bit unsigned integer value
WORD A 16-bit unsigned integer value
SIGNED WORD A 16-bit signed integer value
DWORD A 32-bit unsigned integer value
FIXED A 32-bit fixed point (16.16) value
BYTE[n] "n" bytes.
STRING WORD: string length (number of bytes)
BYTE[length]: characters (in UTF-8)
The \0 character is not included.
PIXEL One pixel, depending on the image pixel format:
RGB: Each pixel have 4 bytes in this order Red, Green, Blue, Alpha.
Grayscale: Each pixel have 2 bytes in the order Value, Alpha.
Indexed: Each pixel uses 1 byte (the index).
  1. Introduction

The format is much like FLI/FLC files, but with different magic number and differents chunks. Also, the color depth can be 8, 16 or 32 for Indexed, Grayscale and RGB respectively, and images are compressed images with zlib. Color palettes are in FLI color chunks (it could be type=11 or type=4). For color depths more than 8bpp, palettes are optional.

To read the sprite:

  • Read the ASE header
  • For each frame do (how many frames? the ASE header has that information):
    • Read the frame header
    • For each chunk in this frame (how many chunks? the frame header has that information)
      • Read the chunk (it should be layer information, a cel or a palette)
  1. Header

A 128-byte header (same as FLC/FLI header, but with other magic number):

Field Details
DWORD File size
WORD Magic number (0xA5E0)
WORD Frames
WORD Width in pixels
WORD Height in pixels
WORD Color depth (bits per pixel)
32 bpp = RGBA
16 bpp = Grayscale
8 bpp = Indexed
DWORD Flags:
1 = Layer opacity has valid value
WORD Speed (milliseconds between frame, like in FLC files) DEPRECATED: You should use the frame duration field from each frame header
DWORD Set be 0
DWORD Set be 0
BYTE Palette entry (index) which represent transparent color in all non-background layers (only for Indexed sprites).
BYTE[3] Ignore these bytes
WORD Number of colors (0 means 256 for old sprites)
BYTE Pixel width (pixel ratio is "pixel width/pixel height"). If this or pixel height field is zero, pixel ratio is 1:1
BYTE Pixel height
BYTE[92] For future (set to zero)
  1. Frames

After the header come the "frames" data. Each frame has this little header of 16 bytes:

Field Details
DWORD Bytes in this frame
WORD Magic number (always 0xF1FA)
WORD Number of "chunks" in this frame
WORD Frame duration (in milliseconds)
BYTE[6] For future (set to zero)

Then each chunk format is:

Field Details
DWORD Chunk size
WORD Chunk type
BYTE[] Chunk data
  1. Chunk Types

Old palette chunk (0x0004)

Ignore this chunk if you find the new palette chunk (0x2019) Aseprite v1.1 saves both chunks 0x0004 and 0x2019 just for backward compatibility.

  WORD          Number of packets
  + For each packet
    BYTE        Number of palette entries to skip from the last packet (start from 0)
    BYTE        Number of colors in the packet (0 means 256)
    + For each color in the packet
      BYTE      Red (0-255)
      BYTE      Green (0-255)
      BYTE      Blue (0-255)

Old palette chunk (0x0011)

Ignore this chunk if you find the new palette chunk (0x2019)

  WORD          Number of packets
  + For each packet
    BYTE        Number of palette entries to skip from the last packet (start from 0)
    BYTE        Number of colors in the packet (0 means 256)
    + For each color in the packet
      BYTE      Red (0-63)
      BYTE      Green (0-63)
      BYTE      Blue (0-63)

Layer Chunk (0x2004)

In the first frame should be a set of layer chunks to determine the entire layers layout:

  WORD          Flags:
                  1 = Visible
                  2 = Editable
                  4 = Lock movement
                  8 = Background
                  16 = Prefer linked cels
                  32 = The layer group should be displayed collapsed
                  64 = The layer is a reference layer
  WORD          Layer type
                  0 = Normal (image) layer
                  1 = Group
  WORD          Layer child level (see NOTE.1)
  WORD          Default layer width in pixels (ignored)
  WORD          Default layer height in pixels (ignored)
  WORD          Blend mode (always 0 for layer set)
                  Normal         = 0
                  Multiply       = 1
                  Screen         = 2
                  Overlay        = 3
                  Darken         = 4
                  Lighten        = 5
                  Color Dodge    = 6
                  Color Burn     = 7
                  Hard Light     = 8
                  Soft Light     = 9
                  Difference     = 10
                  Exclusion      = 11
                  Hue            = 12
                  Saturation     = 13
                  Color          = 14
                  Luminosity     = 15
                  Addition       = 16
                  Subtract       = 17
                  Divide         = 18
  BYTE          Opacity
                  Note: valid only if file header flags field has bit 1 set
  BYTE[3]       For future (set to zero)
  STRING        Layer name

Cel Chunk (0x2005)

This chunk determine where to put a cel in the specified layer/frame.

  WORD          Layer index (see NOTE.2)
  SIGNED WORD   X position
  SIGNED WORD   Y position
  BYTE          Opacity level
  WORD          Cel type
  BYTE[7]       For future (set to zero)

  + For cel type = 0 (Raw Cel):

    WORD        Width in pixels
    WORD        Height in pixels
    PIXEL[]     Raw pixel data: row by row from top to bottom,
                for each scanline read pixels from left to right.

  + For cel type = 1 (Linked Cel):

    WORD        Frame position to link with

  + For cel type = 2 (Compressed Image):

    WORD        Width in pixels
    WORD        Height in pixels
    BYTE[]      ZLIB compressed "Raw Cel" data. 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

Cel Extra Chunk (0x2006)

Adds extra information to the latest read cel.

  DWORD         Flags (set to zero)
                  1 - precise bounds are set
  FIXED         Precise X position
  FIXED         Precise Y position
  FIXED         Width of the cel in the sprite (scaled in real-time)
  FIXED         Height of the cel in the sprite
  BYTE[16]      For future use (set to zero)

Mask Chunk (0x2016) DEPRECATED

  SIGNED WORD   X position
  SIGNED WORD   Y position
  WORD          Width
  WORD          Height
  BYTE[8]       For future (set to zero)
  STRING        Mask name
  BYTE[]        Bit map data (size = height*((width+7)/8))
                Each byte contains 8 pixels (the leftmost pixels are
                packed into the high order bits)

Path Chunk (0x2017)

Never used.

Frame Tags Chunk (0x2018)

  WORD          Number of tags
  BYTE[8]       For future (set to zero)
  + For each tag
    WORD        From frame
    WORD        To frame
    BYTE        Loop animation direction
                0 - Forward
                1 - Reverse
                2 - Ping-pong
    BYTE[8]     For future (set to zero)
    BYTE[3]     RGB values of the tag color
    BYTE        Extra byte (zero)
    STRING      Tag name

Palette Chunk (0x2019)

  DWORD         New palette size (total number of entries)
  DWORD         First color index to change
  DWORD         Last color index to change
  BYTE[8]       For future (set to zero)
  + For each palette entry in [from,to] range (to-from+1 entries)
    WORD        Entry flags:
                  1 = Has name
    BYTE        Red (0-255)
    BYTE        Green (0-255)
    BYTE        Blue (0-255)
    BYTE        Alpha (0-255)
    + If has name bit in entry flags
      STRING    Color name

User Data Chunk (0x2020)

Insert this user data in the last read chunk. E.g. If we've read a layer, this user data belongs to that layer, if we've read a cel, it belongs to that cel, etc.

Field Details
DWORD Flags
1 - Has text
2 - Has color
If flags have bit 1
STRING Text
If flags have bit 2
BYTE Color Red (0-255)
BYTE Color Green (0-255)
BYTE Color Blue (0-255)
BYTE Color Alpha (0-255)

Slice Chunk (0x2022)

Field Details
DWORD Number of "slice keys"
DWORD Flags
1 - It's a 9-patches slice
2 - Has pivot information
DWORD Reserved
STRING Name
For each slice key ...
DWORD Frame number (this slice is valid from
this frame to the end of the animation)
SIGNED WORD Slice X origin coordinate in the sprite
SIGNED WORD Slice Y origin coordinate in the sprite
WORD Slice width (can be 0 if this slice hidden in the
animation from the given frame)
WORD Slice height
If flags have bit 1
SIGNED WORD Center X position (relative to slice bounds)
SIGNED WORD Center Y position
WORD Center width
WORD Center height
If flags have bit 2
WORD Pivot X position (relative to the slice origin)
WORD Pivot Y position (relative to the slice origin)

Notes

NOTE.1

The child level is used to show the relationship of this layer with the last one read, for example:

  Layer name and hierarchy      Child Level
  -----------------------------------------------
  - Background                  0
    `- Layer1                   1
  - Foreground                  0
    |- My set1                  1
    |  `- Layer2                2
    `- Layer3                   1

NOTE.2

The layer index is a number to identify any layer in the sprite, for example:

  Layer name and hierarchy      Layer index
  -----------------------------------------------
  - Background                  0
    `- Layer1                   1
  - Foreground                  2
    |- My set1                  3
    |  `- Layer2                4
    `- Layer3                   5
  1. File Format Changes

  1. The first change from the first release of the new .ase format, is the new frame duration field. This is because now each frame can have different duration.

    How to read both formats (old and new one)? You should set all frames durations to the "speed" field read from the main ASE header. Then, if you found a frame with the frame-duration field > 0, you should update the duration of the frame with that value.