Render several frames from one snapshot

Create a render session when exporting or comparing several frames from the same artwork. Recreate the session after making a revision.

Reuse a frozen render sourceCopy Anchor Link

For repeated frames, create createShotRenderSession(animation) or createEditorialRenderSession(sequence, animations) once. The session validates and copies its inputs during creation. Subsequent edits to the original values do not affect it; create another session for the new revision. Both provide durationFrames, rational frameRate, frame(number) returning a canvas, and png(number) returning a promise of PNG bytes. Callers own returned canvases and should reset their 2D context after use; png() handles canvas cleanup internally. Returned metadata is separate from the private snapshot.

Artwork-cache surfaces, camera-composition surfaces and review-sheet canvases use the shared 32 megapixel surface validator. Nonpositive, fractional or unsafe dimensions report INVALID_ARGUMENT with details.reason: 'INVALID_SURFACE_DIMENSIONS'; area overflow reports RESOURCE_LIMIT with reason: 'SURFACE_PIXEL_LIMIT'. Both include width, height and maxPixels. Numerical overflow during artwork-bound calculation reports RESOURCE_LIMIT, reason: 'ARTWORK_BOUNDS_RANGE' and layerId instead of treating the artwork as empty. These are per-surface checks, not a cap on total render memory. createRenderSession accepts a nonnegative safe-integer maxCacheBytes; zero disables retained artwork caching. Invalid cache budgets report INVALID_ARGUMENT with reason: 'INVALID_CACHE_BUDGET'.

const session = createEditorialRenderSession(sequence, animations);
await writeFile('frame-24.png', await session.png(24));
const mapping = session.resolve(24);

Editorial sessions additionally expose resolve(frame) with the same source mapping as resolveEditorialFrame. The resolver uses precomputed rational conversion and binary search over validated clip starts. createEditorialResolver(sequence, animations) supplies the same isolated mapping and duration without initializing canvas rendering. Resolution is independent of call order. All transitions in a render session must have matching source dimensions, even if a particular frame request does not touch them; cuts may change dimensions. Sessions hold their copied artwork in memory and do not constitute a persisted cache, render queue or memory-budget guarantee.