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//! Decoding and encoding of QOI images
use crate::{
error::{DecodingError, EncodingError},
ColorType, ImageDecoder, ImageEncoder, ImageError, ImageFormat, ImageResult,
};
use std::io::{Cursor, Read, Write};
/// QOI decoder
pub struct QoiDecoder<R> {
decoder: qoi::Decoder<R>,
}
impl<R> QoiDecoder<R>
where
R: Read,
{
/// Creates a new decoder that decodes from the stream ```reader```
pub fn new(reader: R) -> ImageResult<Self> {
let decoder = qoi::Decoder::from_stream(reader).map_err(decoding_error)?;
Ok(Self { decoder })
}
}
impl<'a, R: Read + 'a> ImageDecoder<'a> for QoiDecoder<R> {
type Reader = Cursor<Vec<u8>>;
fn dimensions(&self) -> (u32, u32) {
(self.decoder.header().width, self.decoder.header().height)
}
fn color_type(&self) -> ColorType {
match self.decoder.header().channels {
qoi::Channels::Rgb => ColorType::Rgb8,
qoi::Channels::Rgba => ColorType::Rgba8,
}
}
fn into_reader(mut self) -> ImageResult<Self::Reader> {
let buffer = self.decoder.decode_to_vec().map_err(decoding_error)?;
Ok(Cursor::new(buffer))
}
}
fn decoding_error(error: qoi::Error) -> ImageError {
ImageError::Decoding(DecodingError::new(ImageFormat::Qoi.into(), error))
}
fn encoding_error(error: qoi::Error) -> ImageError {
ImageError::Encoding(EncodingError::new(ImageFormat::Qoi.into(), error))
}
/// QOI encoder
pub struct QoiEncoder<W> {
writer: W,
}
impl<W: Write> QoiEncoder<W> {
/// Creates a new encoder that writes its output to ```writer```
pub fn new(writer: W) -> Self {
Self { writer }
}
}
impl<W: Write> ImageEncoder for QoiEncoder<W> {
fn write_image(
mut self,
buf: &[u8],
width: u32,
height: u32,
color_type: ColorType,
) -> ImageResult<()> {
if !matches!(color_type, ColorType::Rgba8 | ColorType::Rgb8) {
return Err(ImageError::Encoding(EncodingError::new(
ImageFormat::Qoi.into(),
format!("unsupported color type {color_type:?}. Supported are Rgba8 and Rgb8."),
)));
}
// Encode data in QOI
let data = qoi::encode_to_vec(buf, width, height).map_err(encoding_error)?;
// Write data to buffer
self.writer.write_all(&data[..])?;
self.writer.flush()?;
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::fs::File;
#[test]
fn decode_test_image() {
let decoder = QoiDecoder::new(File::open("tests/images/qoi/basic-test.qoi").unwrap())
.expect("Unable to read QOI file");
assert_eq!((5, 5), decoder.dimensions());
assert_eq!(ColorType::Rgba8, decoder.color_type());
}
}
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