Struct image::codecs::webp::lossless::LosslessDecoder

pub(crate) struct LosslessDecoder<R> {
    r: R,
    bit_reader: BitReader,
    frame: LosslessFrame,
    transforms: [Option<TransformType>; 4],
    transform_order: Vec<u8>,
}

Fields

r: R

bit_reader: BitReader

frame: LosslessFrame

transforms: [Option<TransformType>; 4]

transform_order: Vec<u8>

Implementations

impl<R: Read> LosslessDecoder<R>

pub(crate) fn new(r: R) -> LosslessDecoder<R>

Create a new decoder

pub(crate) fn decode_frame(&mut self) -> ImageResult<&LosslessFrame>

Reads the frame

pub(crate) fn decode_frame_implicit_dims( &mut self, width: u16, height: u16, ) -> ImageResult<&LosslessFrame>

fn decode_image_stream( &mut self, xsize: u16, ysize: u16, is_argb_img: bool, ) -> ImageResult<Vec<u32>>

Reads Image data from the bitstream Can be in any of the 5 roles described in the Specification ARGB Image role has different behaviour to the other 4 xsize and ysize describe the size of the blocks where each block has its own entropy code

fn read_transforms(&mut self) -> ImageResult<u16>

Reads transforms and their data from the bitstream

fn adjust_color_map(color_map: &mut [u32])

Adjusts the color map since it’s subtraction coded

fn read_huffman_codes( &mut self, read_meta: bool, xsize: u16, ysize: u16, color_cache: Option<ColorCache>, ) -> ImageResult<HuffmanInfo>

Reads huffman codes associated with an image

fn read_huffman_code(&mut self, alphabet_size: u16) -> ImageResult<HuffmanTree>

Decodes and returns a single huffman tree

fn read_huffman_code_lengths( &mut self, code_length_code_lengths: Vec<u16>, num_symbols: u16, ) -> ImageResult<Vec<u16>>

Reads huffman code lengths

fn decode_image_data( &mut self, width: u16, height: u16, huffman_info: HuffmanInfo, ) -> ImageResult<Vec<u32>>

Decodes the image data using the huffman trees and either of the 3 methods of decoding

fn read_color_cache(&mut self) -> ImageResult<Option<u8>>

Reads color cache data from the bitstream

fn get_copy_distance( bit_reader: &mut BitReader, prefix_code: u16, ) -> ImageResult<usize>

Gets the copy distance from the prefix code and bitstream

fn plane_code_to_distance(xsize: u16, plane_code: usize) -> usize

Gets distance to pixel

Trait Implementations

impl<R: Debug> Debug for LosslessDecoder<R>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.