This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.
The OffscreenCanvas.toBlob() method creates a Blob object representing the image contained in the canvas.
SyntaxEdit
Promise<Blob> OffscreenCanvas.toBlob(type, encoderOptions);
Parameters
typeOptional- A
DOMStringindicating the image format. The default type isimage/png. encoderOptionsOptional- A
Numberbetween0and1indicating image quality if the requested type isimage/jpegorimage/webp. If this argument is anything else, the default value for image quality is used. Other arguments are ignored.
Return value
A Promise returning a Blob object representing the image contained in the canvas.
ExamplesEdit
var offscreen = new OffscreenCanvas(256, 256);
var gl = offscreen.getContext("webgl");
// ... some drawing using the gl context ...
offscreen.toBlob().then(function(blob) {
console.log(blob);
});
// Blob { size: 334, type: "image/png" }SpecificationsEdit
Currently drafted as a proposal: OffscreenCanvas.
Browser compatibilityEdit
[1] This feature is behind a feature preference setting. In about:config, set gfx.offscreencanvas.enabled to true.
See alsoEdit
- The interface defining this method,
OffscreenCanvas.