Struct ProgressiveDecoder 

pub struct ProgressiveDecoder { /* private fields */ }

Decoder that supports scan-by-scan progressive output.

Progressive JPEGs encode image data in multiple scans, each refining the image quality. This decoder lets you consume scans one at a time and output the best available reconstruction at any point.

Implementations

impl ProgressiveDecoder

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

Create from JPEG data. Returns error if not a progressive JPEG. Applies crate::common::types::DecodeLimits::default; use Self::with_limits to tighten (e.g. a max_memory ceiling for the coefficient buffers this decoder holds across scans).

pub fn with_limits(data: &[u8], limits: DecodeLimits) -> Result<Self>

Like Self::new with caller-chosen resource limits, applied from marker parsing onward (issue #355).

pub fn has_multiple_scans(&self) -> bool

Check if the JPEG has multiple scans (i.e., is progressive).

pub fn num_scans(&self) -> usize

Get total number of scans in the image.

pub fn width(&self) -> usize

Get image width in pixels.

pub fn height(&self) -> usize

Get image height in pixels.

pub fn consume_input(&mut self) -> Result<bool>

Consume the next scan from input. Returns true if a scan was consumed, false if all scans are done.

pub fn input_complete(&self) -> bool

Check if all input scans have been consumed.

pub fn scans_consumed(&self) -> usize

Get the number of scans consumed so far.

pub fn output(&self) -> Result<Image>

Output the current image state (after consuming some scans). Returns the best available reconstruction from scans consumed so far. Each call to consume_input() followed by output() gives a progressively better image.

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

Consume all remaining scans and output the final image. Equivalent to calling consume_input() in a loop then output().