rosetta-squint-decode — Rust port

Byte-exact PIL-compatible image decoder library, Rust port (1.70+, edition 2021).

Decodes BMP, PNG, GIF (first frame), JPEG, WebP, TIFF, and HEIC to a raw RGB or RGBA byte buffer matching what PIL.Image.open(...).tobytes() produces.

Quick start

use std::fs;
use rosetta_squint_decode::{decode, detect_format, Channels, DecodeErrorKind};

let bytes = fs::read("photo.jpg")?;

if let Some(fmt) = detect_format(&bytes) {
    println!("detected: {:?}", fmt);
}

match decode(&bytes) {
    Ok(img) => {
        println!("{}x{} channels={:?} format={:?}",
            img.width, img.height, img.channels, img.format);
        // img.data is Vec<u8>, len = width * height * (3 if RGB, 4 if RGBA)
    }
    Err(e) => eprintln!("decode failed: {:?} ({})", e.kind, e.detail),
}

Build + test

cargo build
cargo test --no-fail-fast              # 42 tests, all passing on Linux x86-64

Tests resolve fixtures and goldens from ../../spec/. Run from this crate directory.

API

pub struct DecodedImage {
    pub width: usize,
    pub height: usize,
    pub data: Vec<u8>,          // row-major, length = width * height * (3 or 4)
    pub channels: Channels,
    pub format: Format,
}

pub enum Channels { Rgb, Rgba }
pub enum Format   { Bmp, Png, Gif, Jpeg, Webp, Tiff, Heic }

pub enum DecodeErrorKind {
    UnsupportedFormat,
    CorruptInput,
    Truncated,
    UnsupportedFeature,
}

pub struct DecodeError {
    pub kind: DecodeErrorKind,
    pub format: Option<Format>,
    pub detail: String,
}

Dependencies

Crate dependencies (all pinned in Cargo.toml):

• image = "0.25" (features: png, gif, tiff) — pure-Rust PNG/GIF/TIFF
• mozjpeg-sys = "2" — compiles libjpeg-turbo from source. No system libjpeg needed.
• libwebp-sys2 = "0.1.11" (feature 0_5) — compiles libwebp from source. No system libwebp needed.
• libheif-rs = "2.7" (feature v1_17) — FFI to system libheif, pinned to 1.17 ABI
• thiserror = "1"

System packages required for HEIC support on Ubuntu:

sudo apt install libheif-dev libheif-plugin-libde265 libde265-dev libde265-0 pkg-config

(macOS Homebrew: brew install libheif.)

The first build compiles libjpeg-turbo and libwebp from source — expect ~2 minutes the first time.

Cargo dependency

Not on crates.io yet. Use a path dependency:

[dependencies]
rosetta-squint-decode = { path = "../rosetta-squint-decode/rust/rosetta-squint-decode" }

Format support

See also

• USAGE.md — examples for all 5 ports + end-to-end hash example
• STATUS.md — install matrix, Python parity story, gaps
• ../../spec/SPEC.md — bit-level specification

License

BSD-2-Clause.