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## tiny-png
Tiny Rust PNG decoder.
This decoder can be used without `std` or `alloc` by disabling the `std` feature (enabled by default).
## Goals
- Correctly decode all valid non-interlaced PNG files which can fit in memory.
- Small code size
- No dependencies other than `core`.
- No panics.
- Minimal if any unsafe code
## Non-goals
- Adam7 interlacing (interlaced PNGs are rare, and this would require additional code complexity
— but if you want to add it behind a feature gate, feel free to)
- Significantly sacrificing code size for speed (except maybe with a feature enabled)
- Checking block CRCs (increases code complexity
and there’s already Adler32 checksums for IDAT chunks)
## Example usage
Basic usage:
```rust
let mut buffer = vec![0; 1 << 20]; // hope this is big enough!
let mut png = &include_bytes!("../examples/image.png")[..];
let image = tiny_png::read_png(&mut png, None, &mut buffer).expect("bad PNG");
assert!(png.is_empty(), "extra data after PNG image end");
println!("{}×{} image", image.width(), image.height());
let pixels = image.pixels();
println!("top-left pixel is #{:02x}{:02x}{:02x}", pixels[0], pixels[1], pixels[2]);
// (^ this only makes sense for RGB 8bpc images)
```
Allocate the right number of bytes:
```rust
let mut png = &include_bytes!("../examples/image.png")[..];
let header = tiny_png::read_png_header(&mut png).expect("bad PNG");
let mut buffer = vec![0; header.required_bytes()];
let image = tiny_png::read_png(&mut png, Some(&header), &mut buffer).expect("bad PNG");
assert!(png.is_empty(), "extra data after PNG image end");
println!("{}×{} image", image.width(), image.height());
let pixels = image.pixels();
println!("top-left pixel is #{:02x}{:02x}{:02x}", pixels[0], pixels[1], pixels[2]);
// (^ this only makes sense for RGB 8bpc images)
```
## Features
- `std` (default: enabled) — use standard library. enabling it allows you to read from `BufReader<File>` but
adds `std` as a dependency.
- `adler` (default: disabled) — check Adler-32 checksums. slightly increases code size and
slightly decreases performance but verifies integrity of PNG files.
## Development
A `pre-commit` git hook is provided to run `cargo fmt` and `cargo clippy`. You can install it with:
```sh
ln -s ../../pre-commit .git/hooks/
```
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