OffscreenCanvas.convertToBlob()

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This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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

Syntax

Promise<Blob> OffscreenCanvas.convertToBlob(options);

Parameters

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.

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

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

Specifications

Currently drafted as a proposal: OffscreenCanvas.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
convertToBlob
Experimental
Chrome Full support 69Edge ? Firefox Partial support 46
Notes Alternate Name Disabled
Partial support 46
Notes Alternate Name Disabled
Notes See bug 1390089.
Alternate Name Uses the non-standard name: toBlob
Disabled From version 46: this feature is behind the gfx.offscreencanvas.enabled preference. To change preferences in Firefox, visit about:config.
IE No support NoOpera Full support 56Safari No support NoWebView Android No support NoChrome Android Full support 69Firefox Android Partial support 46
Notes Alternate Name Disabled
Partial support 46
Notes Alternate Name Disabled
Notes See bug 1390089.
Alternate Name Uses the non-standard name: toBlob
Disabled From version 46: this feature is behind the gfx.offscreencanvas.enabled preference. To change preferences in Firefox, visit about:config.
Opera Android Full support YesSafari iOS No support NoSamsung Internet Android No support No

Legend

Full support  
Full support
Partial support  
Partial support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.
Uses a non-standard name.
Uses a non-standard name.

 

See also