Struct ScanlineDecoder 

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

Row-by-row JPEG decoder.

Implementations

impl<'a> ScanlineDecoder<'a>

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

Create a new scanline decoder from raw JPEG data.

pub fn header(&self) -> &FrameHeader

Returns the JPEG frame header.

pub fn output_scanline(&self) -> usize

Returns the number of scanlines read so far.

pub fn set_output_format(&mut self, format: PixelFormat)

Set the output pixel format before starting decode.

pub fn set_fast_upsample(&mut self, fast: bool)

Enable or disable fast (nearest-neighbor) upsampling.

pub fn set_fast_dct(&mut self, fast: bool)

Enable or disable fast DCT for decoding.

pub fn set_dct_method(&mut self, method: DctMethod)

Set the DCT/IDCT method for decoding.

pub fn set_block_smoothing(&mut self, smooth: bool)

Enable or disable inter-block smoothing.

pub fn set_output_colorspace(&mut self, cs: ColorSpace)

Override the output color space.

pub fn set_merged_upsample(&mut self, enabled: bool)

Enable merged upsampling optimization (combines upsample + color convert).

When enabled and subsampling is 4:2:0 or 4:2:2, uses a merged path that avoids intermediate chroma buffers. Faster but uses box-filter replication instead of fancy triangle-filter upsampling.

pub fn set_crop_x(&mut self, x: usize, width: usize)

Set horizontal crop region for scanline-level decoding.

pub fn set_bottom_up(&mut self, bottom_up: bool)

Enable or disable bottom-up row order.

When true, the output rows are reversed after decompression so that row 0 of the output corresponds to the last row of the image. Matches libjpeg-turbo’s TJPARAM_BOTTOMUP on the decode side.

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

Decode and copy one scanline into buf.

pub fn skip_scanlines(&mut self, count: usize) -> Result<usize>

Skip scanlines without copying data.

pub fn finish(self) -> Result<Image>

Finalize and return the complete decoded Image.