Struct PreviewPass 

pub struct PreviewPass { /* private fields */ }

The portable half of a preview pass: which frame the next preview is of, and what becomes of the picture once something has decoded it.

What is not here is the loop. The pass walks forwards one preview at a time and something has to advance it: a thread on native (PreviewIndex), an idle callback in a browser (crate::web_previews). Both drive this, so the stride derivation, the slot bookkeeping and the shrink are written once and a browser preview is the same picture a native one is.

Implementations

impl PreviewPass

pub fn new( options: PreviewOptions, dimensions: &VideoDimensions, frame_count: u64, ) -> Self

A pass over frame_count frames of a dimensions source, with the stride PreviewOptions::stride derives from the two.

pub fn store(&self) -> PreviewStore

A handle on the pictures, for whatever answers seeks from them.

pub fn stride(&self) -> u64

How many frames apart this pass’s previews are.

pub fn next_frame(&self) -> Option<FrameIndex>

The frame the next preview is of, or None once the pass has visited every position.

pub fn accept(&mut self, picture: &VideoFrame, limits: &Limits)

Shrinks picture into the position next_frame named, and advances past it.

A picture that cannot be shrunk leaves its slot empty, exactly as a frame that would not decode does: the index is an optimization, and a gap in it costs a fallback to the neighbor rather than an error the caller has to show.

pub fn skip(&mut self)

Advances past a position whose frame would not decode, leaving its slot empty.