Struct J2kDecoder 

pub struct J2kDecoder<'a> { /* private fields */ }

JPEG 2000 / HTJ2K decoder with WSI-shaped full-frame, ROI, and scaled output methods.

The decoder borrows compressed tile bytes and owns reusable native decode context so repeated operations can avoid reparsing backend state.

Implementations

impl<'a> J2kDecoder<'a>

pub fn inspect(input: &'a [u8]) -> Result<Info, J2kError>

Inspect JP2/J2C/HTJ2K metadata without decoding pixels.

Errors

Returns J2kError when the input cannot be parsed or inspected as a supported JPEG 2000 / HTJ2K image.

pub fn new(input: &'a [u8]) -> Result<Self, J2kError>

Create a decoder from compressed bytes.

Errors

Returns J2kError for unsupported or malformed input.

pub fn from_view(view: J2kView<'a>) -> Result<Self, J2kError>

Create a decoder from a previously parsed J2kView.

Errors

Returns J2kError if the parsed view cannot be promoted to a decoder.

pub fn info(&self) -> &Info

Header-derived image metadata.

pub fn cpu_decode_parallelism(&self) -> CpuDecodeParallelism

Return the CPU decode parallelism policy for this decoder.

pub fn set_cpu_decode_parallelism(&mut self, parallelism: CpuDecodeParallelism)

Set the CPU decode parallelism policy for this decoder.

pub fn bytes(&self) -> &'a [u8]

Original compressed bytes backing this decoder.

pub fn passthrough_candidate(&self) -> Option<PassthroughCandidate<'a>>

Return a byte-preserving passthrough candidate when the native parser classified the compressed syntax and payload shape.

pub fn decode_into( &mut self, out: &mut [u8], stride: usize, fmt: PixelFormat, ) -> Result<DecodeOutcome<Infallible>, J2kError>

Decode the full image into out using stride bytes per output row.

Errors

Returns J2kError when the format is unsupported, the output buffer is too small, or the codestream fails during decode.

pub fn decode_into_with_scratch( &mut self, _pool: &mut J2kScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, ) -> Result<DecodeOutcome<Infallible>, J2kError>

Decode the full image with caller-owned scratch.

The current native full-frame path writes directly into the caller’s output buffer; the pool is accepted to satisfy the shared codec trait and is used by reduced-resolution and row-bounded paths.

Errors

Same as Self::decode_into.

pub fn decode_region_into( &mut self, _pool: &mut J2kScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, ) -> Result<DecodeOutcome<Infallible>, J2kError>

Decode a source-coordinate region into out.

roi is expressed in full-resolution source pixels. The output buffer must hold roi.w * roi.h * fmt.bytes_per_pixel() bytes with the provided row stride.

Errors

Returns J2kError when the region is out of bounds, the output buffer is too small, the format is unsupported, or decode fails.

pub fn decode_scaled_into( &mut self, pool: &mut J2kScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, scale: Downscale, ) -> Result<DecodeOutcome<Infallible>, J2kError>

Decode the full image at a reduced resolution.

scale uses the shared Downscale contract; Downscale::None delegates to full-resolution decode.

Errors

Returns J2kError when the format or scale request is unsupported, the output buffer is too small, or decode fails.

pub fn decode_region_scaled_into( &mut self, pool: &mut J2kScratchPool, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, scale: Downscale, ) -> Result<DecodeOutcome<Infallible>, J2kError>

Decode a source-coordinate region at a reduced resolution.

roi is expressed in full-resolution source pixels. The decoded output covers roi.scaled_covering(scale) in reduced-resolution coordinates.

Errors

Returns J2kError when the region is out of bounds, the scale or pixel format is unsupported, the output buffer is too small, or decode fails.

pub fn decode_rows_u8_bounded<R: RowSink<u8>>( &mut self, sink: &mut R, options: J2kRowDecodeOptions, ) -> Result<DecodeOutcome<Infallible>, DecodeRowsError<J2kError, R::Error>>

Decode rows into a u8 row sink while bounding host output scratch to at most options.max_rows_per_stripe() rows.

Errors

Returns a decode error for unsupported formats or malformed input, and forwards sink errors without converting them to successful decodes.

pub fn decode_rows_u16_bounded<R: RowSink<u16>>( &mut self, sink: &mut R, options: J2kRowDecodeOptions, ) -> Result<DecodeOutcome<Infallible>, DecodeRowsError<J2kError, R::Error>>

Decode rows into a u16 row sink while bounding host output scratch to at most options.max_rows_per_stripe() rows.

Errors

Returns a decode error for unsupported formats or malformed input, and forwards sink errors without converting them to successful decodes.

Trait Implementations

impl ImageCodec for J2kDecoder<'_>

type Error = J2kError

Codec-specific error type.

type Warning = Infallible

Non-fatal warning type returned in successful decode outcomes.

type Pool = J2kScratchPool

Caller-owned scratch pool type used to reuse allocations.

impl<'a> ImageDecode<'a> for J2kDecoder<'a>

type View = J2kView<'a>

Borrowed parse product that can later construct a decoder.

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

Inspect metadata without decoding pixels.

fn parse(input: &'a [u8]) -> Result<Self::View, Self::Error>

Parse compressed bytes into a borrowed view.

fn from_view(view: Self::View) -> Result<Self, Self::Error>

Build a decoder from a parsed view.

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

Decode the full image into caller-owned output.

fn decode_into_with_scratch( &mut self, pool: &mut Self::Pool, out: &mut [u8], stride: usize, fmt: PixelFormat, ) -> Result<DecodeOutcome<Self::Warning>, Self::Error>

Decode the full image into caller-owned output with reusable scratch.

fn decode_region_into( &mut self, pool: &mut Self::Pool, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, ) -> Result<DecodeOutcome<Self::Warning>, Self::Error>

Decode a source-coordinate region into caller-owned output.

fn decode_scaled_into( &mut self, pool: &mut Self::Pool, out: &mut [u8], stride: usize, fmt: PixelFormat, scale: Downscale, ) -> Result<DecodeOutcome<Self::Warning>, Self::Error>

Decode the full image at reduced resolution into caller-owned output.

fn decode_region_scaled_into( &mut self, pool: &mut Self::Pool, out: &mut [u8], stride: usize, fmt: PixelFormat, roi: Rect, scale: Downscale, ) -> Result<DecodeOutcome<Self::Warning>, Self::Error>

Decode a source-coordinate region at reduced resolution into caller-owned output.

fn decode_request_into( &mut self, pool: &mut Self::Pool, out: &mut [u8], stride: usize, fmt: PixelFormat, request: DecodeRequest, ) -> Result<DecodeOutcome<Self::Warning>, Self::Error>

Decode a normalized full/ROI/scaled request into caller-owned output.

impl<'a> ImageDecodeRows<'a, u8> for J2kDecoder<'a>

fn decode_rows<R: RowSink<u8>>( &mut self, sink: &mut R, ) -> Result<DecodeOutcome<Self::Warning>, DecodeRowsError<Self::Error, R::Error>>

Decode rows into sink without requiring one contiguous output buffer.

impl<'a> ImageDecodeRows<'a, u16> for J2kDecoder<'a>

fn decode_rows<R: RowSink<u16>>( &mut self, sink: &mut R, ) -> Result<DecodeOutcome<Self::Warning>, DecodeRowsError<Self::Error, R::Error>>

Decode rows into sink without requiring one contiguous output buffer.