Struct DctScanlineDecoder 

pub struct DctScanlineDecoder { /* private fields */ }

Scanline decoder for DCTDecode (JPEG) data.

Decodes the full JPEG internally on construction, then yields one scanline at a time based on the decoded pixel stride.

Implementations

impl DctScanlineDecoder

pub fn new( jpeg_data: &[u8], width: u32, height: u32, comps: u8, bpc: u8, ) -> Result<Self, DecodeError>

Create a new scanline decoder from JPEG-compressed data.

The row stride is computed automatically as (width * comps * bpc + 7) / 8, matching PDFium’s pitch formula.

pub fn from_decoded( data: Vec<u8>, width: u32, height: u32, comps: u8, bpc: u8, ) -> Self

Create from already-decoded pixel data.

Trait Implementations

impl ScanlineDecoder for DctScanlineDecoder

fn width(&self) -> u32

Image width in pixels. Mirrors PDFium’s GetWidth().

fn height(&self) -> u32

Image height in pixels. Mirrors PDFium’s GetHeight().

fn count_comps(&self) -> u8

Number of color components per pixel (e.g. 1 for gray, 3 for RGB, 4 for CMYK). Mirrors PDFium’s CountComps().

fn bpc(&self) -> u8

Bits per color component (e.g. 1, 8, 16). Mirrors PDFium’s GetBPC().

fn row_stride(&self) -> usize

Number of bytes per row: (width * count_comps * bpc + 7) / 8.

fn decode_scanline(&mut self) -> Result<Option<&[u8]>, DecodeError>

Decode and return the next scanline.

fn reset(&mut self) -> Result<(), DecodeError>

Reset the decoder to the first scanline.

fn current_line(&self) -> Option<usize>

Current line index (0-based), or None if no lines have been read yet.