[−][src]Trait image::ImageDecoder

pub trait ImageDecoder<'a>: Sized {
    type Reader: Read + 'a;
    fn dimensions(&self) -> (u32, u32);

    fn color_type(&self) -> ColorType;

    fn into_reader(self) -> ImageResult<Self::Reader>;

    fn original_color_type(&self) -> ExtendedColorType { ... }

    fn total_bytes(&self) -> u64 { ... }

    fn scanline_bytes(&self) -> u64 { ... }

    fn read_image(self, buf: &mut [u8]) -> ImageResult<()> { ... }

    fn read_image_with_progress<F: Fn(Progress)>(
        self, 
        buf: &mut [u8], 
        progress_callback: F
    ) -> ImageResult<()> { ... }
}

The trait that all decoders implement

Associated Types

type Reader: Read + 'a

The type of reader produced by into_reader.

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Required methods

fn dimensions(&self) -> (u32, u32)

Returns a tuple containing the width and height of the image

fn color_type(&self) -> ColorType

Returns the color type of the image data produced by this decoder

fn into_reader(self) -> ImageResult<Self::Reader>

Returns a reader that can be used to obtain the bytes of the image. For the best performance, always try to read at least scanline_bytes from the reader at a time. Reading fewer bytes will cause the reader to perform internal buffering.

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Provided methods

fn original_color_type(&self) -> ExtendedColorType

Retuns the color type of the image file before decoding

fn total_bytes(&self) -> u64

Returns the total number of bytes in the decoded image.

This is the size of the buffer that must be passed to read_image or read_image_with_progress. The returned value may exceed usize::MAX, in which case it isn't actually possible to construct a buffer to decode all the image data into.

fn scanline_bytes(&self) -> u64

Returns the minimum number of bytes that can be efficiently read from this decoder. This may be as few as 1 or as many as total_bytes().

fn read_image(self, buf: &mut [u8]) -> ImageResult<()>

Returns all the bytes in the image.

This function takes a slice of bytes and writes the pixel data of the image into it. Although not required, for certain color types callers may want to pass buffers which are aligned to 2 or 4 byte boundaries to the slice can be cast to a u16 or u32. To accommodate such casts, the returned contents will always be in native endian.

Panics

This function panics if buf.len() != self.total_bytes().

Examples

use zerocopy::{AsBytes, FromBytes};
fn read_16bit_image(decoder: impl ImageDecoder) -> Vec<16> {
    let mut buf: Vec<u16> = vec![0; decoder.total_bytes()/2];
    decoder.read_image(buf.as_bytes());
    buf
}

fn read_image_with_progress<F: Fn(Progress)>(
    self,
    buf: &mut [u8],
    progress_callback: F
) -> ImageResult<()>

Same as read_image but periodically calls the provided callback to give updates on loading progress.

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Implementors

impl<'a, R: 'a + BufRead> ImageDecoder<'a> for HDRAdapter<R>[src]

type Reader = HdrReader<R>

impl<'a, R: 'a + Read + Seek> ImageDecoder<'a> for BmpDecoder<R>[src]

type Reader = BmpReader<R>

impl<'a, R: 'a + Read + Seek> ImageDecoder<'a> for IcoDecoder<R>[src]

type Reader = IcoReader<R>

impl<'a, R: 'a + Read + Seek> ImageDecoder<'a> for TgaDecoder<R>[src]

type Reader = TGAReader<R>

impl<'a, R: 'a + Read + Seek> ImageDecoder<'a> for TiffDecoder<R>[src]

type Reader = TiffReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for DdsDecoder<R>[src]

type Reader = DXTReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for DxtDecoder<R>[src]

type Reader = DXTReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for FarbfeldDecoder<R>[src]

type Reader = FarbfeldReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for GifDecoder<R>[src]

type Reader = GifReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for JpegDecoder<R>[src]

type Reader = JpegReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for PngDecoder<R>[src]

type Reader = PNGReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for PnmDecoder<R>[src]

type Reader = PnmReader<R>

impl<'a, R: 'a + Read> ImageDecoder<'a> for WebPDecoder<R>[src]

type Reader = WebpReader<R>

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