Prismv0.4
Guides

Export a PNG

Wait for one Prism-owned paint pass, then export with the normal canvas API.

Prism does not export image data itself. It gives you a deterministic readiness point before you call canvas APIs.

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

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

If your surfaces include images, make sure they are loaded or decoded before paintOnce().

await Promise.all(
  Array.from(document.images).map((image) =>
    image.complete ? undefined : image.decode()
  )
);

await document.fonts.ready;
await runtime.paintOnce();
canvas.toBlob((blob) => {
  // Save or upload the PNG blob.
}, "image/png");

Notes

  • paintOnce() works without start().
  • paintOnce() resolves after one Prism-owned paint pass.
  • paintOnce() does not call toBlob() or toDataURL() for you.

Cleanup

Stop painting, dispose surfaces, and return DOM ownership cleanly.

Convert coordinates

Convert between client, CSS-pixel, and backing-store canvas coordinates.

On this page

NotesRelated