# [Rust](https://www.rust-lang.org) version of [LodePNG](http://lodev.org/lodepng)
This is a pure Rust PNG image decoder and encoder. Allows easy reading and writing of PNG files without any system dependencies.
The easiest way to use LodePNG is to include the [lodepng crate](https://crates.io/crates/lodepng).
To do so, add this to your `Cargo.toml`:
```toml
[dependencies]
lodepng = "2.0.0"
```
See [API reference](https://docs.rs/lodepng/) for details. Requires Rust 1.21 or later.
### Loading image example
```rust
let image = lodepng::decode32_file("in.png")?;
```
returns image of type `lodepng::Bitmap<lodepng::RGBA<u8>>` with fields `.width`, `.height`, and `.buffer` (the buffer is a `Vec`).
The RGB/RGBA pixel types are from the [RGB crate](https://crates.io/crates/rgb), which you can import separately to use the same pixel struct throughout the program, without casting. But if you want to read the image buffer as bunch of raw bytes, ignoring the RGB(A) pixel structure, use:
```rust
[dependencies]
rgb = "0.8"
```
```rust
extern crate rgb;
use rgb::*;
…
let bytes: &[u8] = image.buffer.as_bytes();
```
### Saving image example
```rust
lodepng::encode32_file("out.png", &buffer, width, height)
```
The buffer can be a slice of any type as long as it has 4 bytes per element (e.g. `struct RGBA` or `(u8,u8,u8,u8)`).
### Advanced
```rust
let mut state = lodepng::State::new();
state.remember_unknown_chunks(true);
match state.decode("in.png") {
Ok(lodepng::Image::RGB(image)) => {…}
Ok(lodepng::Image::RGBA(image)) => {…}
Ok(lodepng::Image::RGBA16(image)) => {…}
Ok(lodepng::Image::Gray(image)) => {…}
Ok(_) => {…}
Err(err) => {…}
}
for chunk in state.info_png().unknown_chunks() {
println!("{:?} = {:?}", chunk.name(), chunk.data());
}
// Color profile (to be used with e.g. LCMS2)
let icc_data = state.info_png().get_icc();
```
## Upgrading from 1.x
* `CVec` has been replaced with a regular `Vec`. Delete extra `.as_ref()` that the compiler may complain about.
* `LCT_*` constants have been changed to `ColorType::*`.
* `Chunk`/`Chunks` renamed to `ChunkRef`/`ChunksIter`
* `auto_convert` is a boolean
* `bitdepth` has a getter/setter
* There is no C any more!