Struct WebPDecoder

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pub struct WebPDecoder<R> {Show 13 fields
    r: R,
    memory_limit: usize,
    width: u32,
    height: u32,
    kind: ImageKind,
    animation: AnimationState,
    is_lossy: bool,
    has_alpha: bool,
    num_frames: u32,
    loop_count: LoopCount,
    loop_duration: u64,
    chunks: HashMap<WebPRiffChunk, Range<u64>>,
    webp_decode_options: WebPDecodeOptions,
}

Expand description

WebP image format decoder.

Fields§

§r: R§memory_limit: usize§width: u32§height: u32§kind: ImageKind§animation: AnimationState§is_lossy: bool§has_alpha: bool§num_frames: u32§loop_count: LoopCount§loop_duration: u64§chunks: HashMap<WebPRiffChunk, Range<u64>>§webp_decode_options: WebPDecodeOptions

Implementations§

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impl<R: BufRead + Seek> WebPDecoder<R>

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pub fn new(r: R) -> Result<Self, DecodingError>

Create a new WebPDecoder from the reader r. The decoder performs many small reads, so the reader should be buffered.

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pub fn new_with_options( r: R, webp_decode_options: WebPDecodeOptions, ) -> Result<Self, DecodingError>

Create a new WebPDecoder from the reader r with the options WebPDecodeOptions. The decoder performs many small reads, so the reader should be buffered.

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fn read_data(&mut self) -> Result<(), DecodingError>

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pub fn set_memory_limit(&mut self, limit: usize)

Sets the maximum amount of memory that the decoder is allowed to allocate at once.

TODO: Some allocations currently ignore this limit.

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pub fn background_color_hint(&self) -> Option<[u8; 4]>

Get the background color specified in the image file if the image is extended and animated webp.

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pub fn set_background_color( &mut self, color: [u8; 4], ) -> Result<(), DecodingError>

Sets the background color if the image is an extended and animated webp.

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

Returns the (width, height) of the image in pixels.

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pub fn has_alpha(&self) -> bool

Returns whether the image has an alpha channel. If so, the pixel format is Rgba8 and otherwise Rgb8.

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pub fn is_animated(&self) -> bool

Returns true if the image is animated.

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pub fn is_lossy(&mut self) -> bool

Returns whether the image is lossy. For animated images, this is true if any frame is lossy.

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pub fn num_frames(&self) -> u32

Returns the number of frames of a single loop of the animation, or zero if the image is not animated.

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pub fn loop_count(&self) -> LoopCount

Returns the number of times the animation should loop.

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pub fn loop_duration(&self) -> u64

Returns the total duration of one loop through the animation in milliseconds, or zero if the image is not animated.

This is the sum of the durations of all individual frames of the image.

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fn read_chunk( &mut self, chunk: WebPRiffChunk, max_size: usize, ) -> Result<Option<Vec<u8>>, DecodingError>

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pub fn icc_profile(&mut self) -> Result<Option<Vec<u8>>, DecodingError>

Returns the raw bytes of the ICC profile, or None if there is no ICC profile.

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pub fn exif_metadata(&mut self) -> Result<Option<Vec<u8>>, DecodingError>

Returns the raw bytes of the EXIF metadata, or None if there is no EXIF metadata.

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pub fn xmp_metadata(&mut self) -> Result<Option<Vec<u8>>, DecodingError>

Returns the raw bytes of the XMP metadata, or None if there is no XMP metadata.

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pub fn output_buffer_size(&self) -> Option<usize>

Returns the number of bytes required to store the image or a single frame, or None if that would take more than usize::MAX bytes.

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

Returns the raw bytes of the image. For animated images, this is the first frame.

Fails with ImageTooLarge if buf has length different than output_buffer_size()

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pub fn read_frame(&mut self, buf: &mut [u8]) -> Result<u32, DecodingError>

Reads the next frame of the animation.

The frame contents are written into buf and the method returns the duration of the frame in milliseconds. If there are no more frames, the method returns DecodingError::NoMoreFrames and buf is left unchanged.