OffscreenCanvas.convertToBlob()

The OffscreenCanvas.convertToBlob() method creates a Blob object representing the image contained in the canvas.

Promise<Blob> OffscreenCanvas.convertToBlob(options);

options Optional

You can specify several options when converting your OffscreenCanvas object into a Blob object, for example:

const blob = offscreenCanvas.convertToBlob({
  type: "image/jpeg",
  quality: 0.95
});

options:

• type: A DOMString indicating the image format. The default type is image/png.
• quality: A Number between 0 and 1 indicating image quality if the type option is image/jpeg or image/webp. If this argument is anything else, the default value for image quality is used. Other arguments are ignored.

A Promise returning a Blob object representing the image contained in the canvas.

var offscreen = new OffscreenCanvas(256, 256);
var gl = offscreen.getContext("webgl");

// ... some drawing using the gl context ...

offscreen.convertToBlob().then(function(blob) {
  console.log(blob);
});

// Blob { size: 334, type: "image/png" }

Currently drafted as a proposal: OffscreenCanvas.

• The interface defining this method, OffscreenCanvas.