This crate aims to provide an interface that parses and decompresses GIF files. It exposes a simple API with 2 functions: one for parsing bytes into a compressed GIF data stream, and another for decompressing the stream into a list of image frames.
This repository also contains a crate to render GIFs. It provides a command-line executable that
uses minifb to render pixels.
jif aims to decode any GIF from GIPHY. Any deviation from Giphy's rendering should be
considered a bug.
The following legend defines the symbols used in this grammar:
| Symbol | Definition |
|---|---|
<> |
grammar word |
::= |
defines symbol |
* |
zero or more occurrences |
+ |
one or more occurrences |
| |
alternate element |
[] |
optional element |
<GIF Data Stream> ::= Header <Logical Screen> <Data>* Trailer
<Logical Screen> ::= Logical Screen Descriptor [Global Color Table]<Data> ::= <Graphic Block> | <Special-Purpose Block><Graphic Block> ::= [Graphic Control Extension] <Graphic-Rendering Block><Graphic-Rendering Block> ::= <Table-Based Image> | Plain Text Extension<Table-Based Image> ::= Image Descriptor [Local Color Table] Image Data
<Special-Purpose Block> ::= Application Extension | Comment Extension
jif uses an AFL fuzzer to assert correctness. GIFs that crash are stored in /regression for the purpose of running
regression tests.
To fuzz, simply:
./fuzz.sh
https://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
https://web.archive.org/web/20050217131148/http://www.danbbs.dk/~dino/whirlgif/lzw.html
https://www.w3.org/Graphics/GIF/spec-gif89a.txt