aseprite/docs/files/ase.txt

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ASE Files (.ASE) Format description
Copyright (C) 2004-2009 by David Capello
----------------------------------------------------------------------
1. References
2. Introduction
3. Header
4. Frames
5. New chunk types
6. File Format Changes
========================================
1. References
========================================
ASE files use Intel (little-endian) byte order.
BYTE An 8-bit unsigned integer value
WORD A 16-bit unsigned integer value
DWORD A 32-bit unsigned integer value
LONG A 32-bit signed integer value
BYTE[n] "n" bytes.
RECT Four LONGs (in the order: x-pos, y-pos, width, heigth)
STRING length=WORD (how many characters to read next)
string=BYTE[length]
The \0 character isn't included.
========================================
2. 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 the images are more easy
to read (there aren't differences with old frames). The palette isn't
included for color depths more than 8, but when the sprite is 8 bpp,
the palette is in a FLI color chunk (it could be type=11 or type=4).
See fli.txt for details.
To read the sprite, just do this:
* Read the ASE header (section 3)
* For each frame do (how many frames? the ASE header has that
information):
+ Read the frame header (section 4)
+ 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)
========================================
3. Header
========================================
A 128-byte header (same as FLC/FLI header, but with other magic
number):
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 (must be 0)
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
DWORD Ignore this field
WORD Number of colors (0 means 256 for old sprites)
BYTE[94] For future (set to zero)
========================================
4. Frames
========================================
After the header come the "frames" data. Each frame has this little
header of 16 bytes:
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:
DWORD Chunk size
WORD Chunk type
BYTE[] Chunk data
========================================
5. New chunk types
========================================
Layer Chunk (0x2004)
----------------------------------------
In the first frame should be a set of layer chunks to determine the
entire layers layout:
WORD Flags:
LAYER_IS_READABLE = 0x0001
LAYER_IS_WRITABLE = 0x0002
LAYER_IS_LOCKMOVE = 0x0004
LAYER_IS_BACKGROUND = 0x0008
WORD Layer type (0=normal (image) layer, 1=layer set)
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)
BLEND_MODE_NORMAL = 0
BLEND_MODE_DISSOLVE = 1
BLEND_MODE_MULTIPLY = 2
BLEND_MODE_SCREEN = 3
BLEND_MODE_OVERLAY = 4
BLEND_MODE_HARD_LIGHT = 5
BLEND_MODE_DODGE = 6
BLEND_MODE_BURN = 7
BLEND_MODE_DARKEN = 8
BLEND_MODE_LIGHTEN = 9
BLEND_MODE_ADDITION = 10
BLEND_MODE_SUBTRACT = 11
BLEND_MODE_DIFFERENCE = 12
BLEND_MODE_HUE = 13
BLEND_MODE_SATURATION = 14
BLEND_MODE_COLOR = 15
BLEND_MODE_LUMINOSITY = 16
BLEND_MODE_COPY = 17
BYTE[4] 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)
WORD X position
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
BYTE[] Pixel data (see NOTE.3)
+ For cel type = 1 (Linked Cel):
WORD Frame position to link with
+ For cel type = 2 (RLE compressed image, only for Indexed images):
WORD Width in pixels
WORD Height in pixels
XXXXX -todo-
Mask Chunk (0x2016) DEPRECATED
----------------------------------------
WORD X position
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.
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
NOTE.3: The raw pixel data is saved row by row from top to bottom, and
each scanline is from pixel by pixel from left to right.
In RGB images, each pixel have 4 bytes in the order R, G, B, A.
In Grayscale images, each pixel have 2 bytes in the order K, A.
In Indexed images, each pixel have 1 byte (the index).
========================================
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.
2) The format of ASE 0.6 beta has a header with a background color
after the two last reserved DWORD
...
WORD Speed (milliseconds between frame, like in FLC files)
DWORD Set be 0
DWORD Set be 0
DWORD Background-color <------ *
BYTE[96] For future (set to zero)
* This field is deprecated, and now it should be 0 or his value
should be completely ignored. The only drawback is that the
sprite will have a transparent background instead of a colored
one.