rememberFilmstripFrames
Remembers the frames of a timeline strip over composition, and closes them when this leaves composition.
Fetching is driven by FilmstripFrames.onVisibleRange, so a strip that never reports its window never decodes anything. Requests are served one at a time, since extraction running alongside a preview contends with it for the device's decoders.
The cache is dropped whenever anything that would change a rendered frame changes: an edit that moves the pixels, or a different heightPx. An edit that changes nothing a frame is rendered from, such as a clip's gain, keeps every frame already held. A different set of positions keeps the frames whose position survives and closes the rest, so a strip being zoomed only asks for the positions it gained.
Return
State keyed to renderer, the same instance across recompositions.
Parameters
What renders the frames, usually the Filmstrip itself.
The edit to render from.
Where in the composition each strip item sits.
The height to render at, in pixels. Null renders at the composition's own output height, and a height of zero or less renders nothing.
How many bytes of decoded frames to hold.
How many items either side of the visible ones to keep ready.
The export these frames stand in for, which renders them at the HDR grade that export resolves to.