Struct Decoder 

pub struct Decoder<'a> { /* private fields */ }

A borrowed view of a JPEG stream ready to decode. Constructed via Decoder::new or Decoder::from_view. Decoder<'a>: Send + Sync.

Implementations

impl Decoder<'_>

pub fn decode_request( &self, request: DecodeRequest, ) -> Result<(Vec<u8>, DecodeOutcome), JpegError>

Decode into a freshly allocated tightly packed buffer using a request object instead of a method-name cross-product.

Errors

Returns an output-geometry, unsupported-format, or scan decode error.

impl Decoder<'_>

pub fn decode_into( &self, out: &mut [u8], stride: usize, fmt: PixelFormat, ) -> Result<DecodeOutcome, JpegError>

Decode the full image into the caller’s buffer.

Errors

• JpegError::OutputBufferTooSmall or JpegError::InvalidStride if the provided buffer/stride cannot hold the image at fmt.
• JpegError::NotImplemented if fmt requests a raw output the current release does not emit (e.g. RawYCbCr8).
• Any entropy- or structural-decode error from the scan walker.

pub fn decode_scaled_into( &self, out: &mut [u8], stride: usize, fmt: PixelFormat, scale: Downscale, ) -> Result<DecodeOutcome, JpegError>

Decode the full image into the caller’s buffer using the core PixelFormat + Downscale contract.

Errors

Returns an output-buffer, unsupported-format, or scan decode error.

pub fn decode_into_with_scratch( &self, pool: &mut ScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, ) -> Result<DecodeOutcome, JpegError>

Decode the full image into the caller’s buffer, reusing the supplied ScratchPool. On a long-running tile batch this eliminates the per-tile allocation of stripe buffers, the DC predictor, and the chroma upsample rows — the realistic WSI reader shape. The first call against a fresh pool does the allocation; subsequent calls at the same-or-smaller shape reuse the underlying Vecs.

Errors

Identical to Self::decode_into.

pub fn decode_scaled_into_with_scratch( &self, pool: &mut ScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, scale: Downscale, ) -> Result<DecodeOutcome, JpegError>

Self::decode_scaled_into with caller-owned scratch.

Errors

Returns an output-buffer, unsupported-format, or scan decode error.

pub fn decode_region_into( &self, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, ) -> Result<DecodeOutcome, JpegError>

Decode a rectangular region of the image into the caller’s buffer.

roi is expressed in source-image coordinates. If fmt requests a downscaled output, the written pixels cover the corresponding bounding box in the scaled image grid.

Errors

Returns an invalid-region, output-buffer, unsupported-format, or scan decode error.

pub fn decode_region_scaled_into( &self, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, scale: Downscale, ) -> Result<DecodeOutcome, JpegError>

Decode roi into the caller’s buffer using the core PixelFormat + Downscale contract.

Errors

Returns an invalid-region, output-buffer, unsupported-format, or scan decode error.

pub fn decode_region_scaled_into_with_scratch( &self, pool: &mut ScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, scale: Downscale, ) -> Result<DecodeOutcome, JpegError>

Self::decode_region_scaled_into with caller-owned scratch.

Errors

Returns an invalid-region, output-buffer, unsupported-format, or scan decode error.

impl Decoder<'_>

pub fn decode_rows<S>(&self, sink: &mut S) -> Result<DecodeOutcome, JpegError>

where S: RowSink<u8, Error = JpegError>,

Decode the full image into rows delivered to sink.

DCT-backed and 8-bit lossless color paths emit interleaved RGB8 rows. Lossless 16-bit grayscale SOF3 emits little-endian Gray16 rows, and supported lossless 16-bit color SOF3 emits little-endian Rgb16 rows.

Errors

Returns a scan decode error or an error reported by sink.

pub fn decode_rows_with_scratch<S>( &self, pool: &mut ScratchPool, sink: &mut S, ) -> Result<DecodeOutcome, JpegError>

where S: RowSink<u8, Error = JpegError>,

Self::decode_rows with caller-owned scratch. See Self::decode_into_with_scratch for the reuse contract.

Errors

Returns a scan decode error or an error reported by sink.

pub fn decode_component_rows_with_scratch<W>( &self, pool: &mut ScratchPool, writer: &mut W, ) -> Result<DecodeOutcome, JpegError>

where W: ComponentRowWriter,

Decode the full image into component rows.

Errors

Returns a scan decode error or an error reported by writer.

pub fn decode_region_component_rows_with_scratch<W>( &self, pool: &mut ScratchPool, writer: &mut W, roi: Rect, scale: Downscale, ) -> Result<DecodeOutcome, JpegError>

where W: ComponentRowWriter,

Decode roi into component rows, optionally at a reduced scale.

Errors

Returns an invalid-region or scan error, or an error reported by writer.

impl<'a> Decoder<'a>

pub fn inspect(input: &'a [u8]) -> Result<Info, JpegError>

Parse the headers without decoding pixels. The parser walks headers up to the first SOS and then performs a lightweight marker scan so Info::scan_count reflects all scans in the file.

Errors

Returns any structural, unsupported-SOF, or sanity-check error encountered before the Start-of-Scan marker. See JpegError.

pub fn new(input: &'a [u8]) -> Result<Self, JpegError>

Build a decoder ready for decode_into. Parses the full header, pre- builds every referenced Huffman table, and validates that the stream is one of the SOFs this release implements.

Errors

• Any parse error encountered before SOS (see Self::inspect).
• JpegError::NotImplemented for SOFs that parse but are not yet decodable for the requested shape (for example Progressive12 or unsupported Lossless predictors).
• JpegError::MissingHuffmanTable if the scan references a DC/AC table slot that was never defined by a DHT segment.

pub fn from_view(view: JpegView<'a>) -> Result<Self, JpegError>

Build a decoder from a previously parsed JpegView.

Errors

Returns an error when the view describes an unsupported JPEG shape or references missing or invalid coding tables.

pub fn from_view_in_context( view: JpegView<'a>, ctx: &mut DecoderContext, ) -> Result<Self, JpegError>

Build a decoder from a previously parsed JpegView, reusing shared compiled DHT/DQT state from ctx when table contents repeat.

Errors

Returns an error when the view describes an unsupported JPEG shape or references missing or invalid coding tables.

pub fn info(&self) -> &Info

The parsed header as a public Info.

Trait Implementations

impl<'a> Debug for Decoder<'a>

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

Formats the value using the given formatter.