This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The HTMLCanvasElement.mozOpaque property is a Boolean reflecting the moz-opaque HTML attribute of the <canvas> element. It lets the canvas know whether or not translucency will be a factor. If the canvas knows there's no translucency, painting performance can be optimized.


var opaque = canvas.mozOpaque;
canvas.mozOpaque = true;


Given this <canvas> element:

<canvas id="canvas" width="300" height="300" moz-opaque></canvas>

You can get or set the mozOpaque property. For example, you could conditionally set it to true if mimeType == 'image/jpeg', or similar, to gain performance in your application when translucency is not needed.

var canvas = document.getElementById('canvas');
console.log(canvas.mozOpaque); // true
// deactivate it
canvas.mozOpaque = false;


Not part of any standard.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support No support 3.5 (1.9.1) No support No support No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support No support 1.0 (1.9.1) No support No support No support

See also

Document Tags and Contributors

 Contributors to this page: nmve, fscholz, teoli
 Last updated by: nmve,