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aseprite/docs/ase-file-specs.md
David Capello 02b225868d Fix slices' user data serialization on .ase format
2017-04-12 08:57:02 -03:00

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Aseprite File Format (.ase/.aseprite) Specifications
====================================================
> Copyright (C) 2001-2017 by David Capello
1. [References](#1-references)
2. [Introduction](#2-introduction)
3. [Header](#3-header)
4. [Frames](#4-frames)
5. [Chunk Types](#5-chunk-types)
6. [File Format Changes](#6-file-format-changes)
1. 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).
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 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](#3-header)
* For each frame do (how many frames? the ASE header has that information):
+ Read the [frame header](#4-frames)
+ 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):
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)
4. 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
5. 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
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
```
6. 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.
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