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extern crate png;
use self::png::HasParameters;
use std::io::{self, Cursor, Read, Write};
use color::ColorType;
use image::{ImageDecoder, ImageError, ImageResult};
pub struct PNGDecoder<R: Read> {
colortype: ColorType,
reader: png::Reader<R>,
}
impl<R: Read> PNGDecoder<R> {
pub fn new(r: R) -> ImageResult<PNGDecoder<R>> {
let decoder = png::Decoder::new(r);
let (_, mut reader) = decoder.read_info()?;
let colortype = reader.output_color_type().into();
Ok(PNGDecoder { colortype, reader })
}
}
impl<R: Read> ImageDecoder for PNGDecoder<R> {
type Reader = Cursor<Vec<u8>>;
fn dimensions(&self) -> (u64, u64) {
let (w, h) = self.reader.info().size();
(w as u64, h as u64)
}
fn colortype(&self) -> ColorType {
self.colortype
}
fn into_reader(self) -> ImageResult<Self::Reader> {
Ok(Cursor::new(self.read_image()?))
}
fn read_image(mut self) -> ImageResult<Vec<u8>> {
let mut data = vec![0; self.reader.output_buffer_size()];
self.reader.next_frame(&mut data)?;
Ok(data)
}
}
pub struct PNGEncoder<W: Write> {
w: W,
}
impl<W: Write> PNGEncoder<W> {
pub fn new(w: W) -> PNGEncoder<W> {
PNGEncoder { w }
}
pub fn encode(self, data: &[u8], width: u32, height: u32, color: ColorType) -> io::Result<()> {
let (ct, bits) = color.into();
let mut encoder = png::Encoder::new(self.w, width, height);
encoder.set(ct).set(bits);
let mut writer = try!(encoder.write_header());
writer.write_image_data(data).map_err(|e| e.into())
}
}
impl From<(png::ColorType, png::BitDepth)> for ColorType {
fn from((ct, bits): (png::ColorType, png::BitDepth)) -> ColorType {
use self::png::ColorType::*;
let bits = bits as u8;
match ct {
Grayscale => ColorType::Gray(bits),
RGB => ColorType::RGB(bits),
Indexed => ColorType::Palette(bits),
GrayscaleAlpha => ColorType::GrayA(bits),
RGBA => ColorType::RGBA(bits),
}
}
}
impl From<ColorType> for (png::ColorType, png::BitDepth) {
fn from(ct: ColorType) -> (png::ColorType, png::BitDepth) {
use self::png::ColorType::*;
let (ct, bits) = match ct {
ColorType::Gray(bits) => (Grayscale, bits),
ColorType::RGB(bits) => (RGB, bits),
ColorType::Palette(bits) => (Indexed, bits),
ColorType::GrayA(bits) => (GrayscaleAlpha, bits),
ColorType::RGBA(bits) => (RGBA, bits),
ColorType::BGRA(bits) => (RGBA, bits),
ColorType::BGR(bits) => (RGB, bits),
};
(ct, png::BitDepth::from_u8(bits).unwrap())
}
}
impl From<png::DecodingError> for ImageError {
fn from(err: png::DecodingError) -> ImageError {
use self::png::DecodingError::*;
match err {
IoError(err) => ImageError::IoError(err),
Format(desc) => ImageError::FormatError(desc.into_owned()),
InvalidSignature => ImageError::FormatError("invalid signature".into()),
CrcMismatch { .. } => ImageError::FormatError("CRC error".into()),
Other(desc) => ImageError::FormatError(desc.into_owned()),
CorruptFlateStream => {
ImageError::FormatError("compressed data stream corrupted".into())
}
}
}
}