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.
Syntax
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.
Examples
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" }
Specifications
Currently drafted as a proposal: OffscreenCanvas.
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | Not supported | 46 (46) [1] | Not supported | Not supported | Not supported |
| Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|
| Basic support | Not supported | 46.0 (46) [1] | Not supported | Not supported | Not supported |
[1] This feature is behind a feature preference setting. In about:config, set gfx.offscreencanvas.enabled to true.
See also
- The interface defining this method,
OffscreenCanvas.