paintOnce()

paintOnce() waits for a Prism-owned paint pass. It does not export image data.

await document.fonts.ready;
await runtime.paintOnce();

const blob = await new Promise<Blob | null>((resolve) => {
  canvas.toBlob(resolve, "image/png");
});

Use it when you need a deterministic readiness point before calling normal canvas APIs such as toBlob() or toDataURL().

paintOnce() works without starting the runtime loop.