Crate png

PNG encoder and decoder

This crate contains a PNG encoder and decoder. It supports reading of single lines or whole frames.

The decoder

The most important types for decoding purposes are Decoder and Reader. They both wrap a std::io::Read. Decoder serves as a builder for Reader. Calling Decoder::read_info reads from the Read until the image data is reached.

Using the decoder

use std::fs::File;

// The decoder is a build for reader and can be used to set various decoding options
// via `Transformations`. The default output transformation is `Transformations::EXPAND
// | Transformations::STRIP_ALPHA`.
let decoder = png::Decoder::new(File::open("tests/pngsuite/basi0g01.png").unwrap());
let (info, mut reader) = decoder.read_info().unwrap();
// Allocate the output buffer.
let mut buf = vec![0; info.buffer_size()];
// Read the next frame. An APNG might contain multiple frames.
reader.next_frame(&mut buf).unwrap();
// Inspect more details of the last read frame.
let in_animation = reader.info().frame_control.is_some();

Encoder

Using the encoder

// For reading and opening files
use std::path::Path;
use std::fs::File;
use std::io::BufWriter;

let path = Path::new(r"/path/to/image.png");
let file = File::create(path).unwrap();
let ref mut w = BufWriter::new(file);

let mut encoder = png::Encoder::new(w, 2, 1); // Width is 2 pixels and height is 1.
encoder.set_color(png::ColorType::RGBA);
encoder.set_depth(png::BitDepth::Eight);
let mut writer = encoder.write_header().unwrap();

let data = [255, 0, 0, 255, 0, 0, 0, 255]; // An array containing a RGBA sequence. First pixel is red and second pixel is black.
writer.write_image_data(&data).unwrap(); // Save

Modules

chunk

Chunk types and functions

Structs

AnimationControl	Animation control information
Decoder	PNG Decoder
Encoder	PNG Encoder
FrameControl	Frame control information
Info	PNG info struct
Limits	Limits on the resources the Decoder is allowed too use
OutputInfo	Output info
PixelDimensions	Pixel dimensions information
Reader	PNG reader (mostly high-level interface)
StreamWriter	Streaming png writer
StreamingDecoder	PNG StreamingDecoder (low-level interface)
Transformations	Output transformations
Writer	PNG writer

Enums

BitDepth	Bit depth of the png file
BlendOp	How pixels are written into the buffer.
ColorType	Describes the layout of samples in a pixel
Compression	The type and strength of applied compression.
Decoded	Result of the decoding process
DecodingError
DisposeOp	How to reset buffer of an animated png (APNG) at the end of a frame.
EncodingError
FilterType	The byte level filter applied to scanlines to prepare them for compression.
Unit	Physical unit of the pixel dimensions