HTMLCanvasElement.mozOpaque

The non-standard 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.

This has been standardized as setting the alpha option to false when creating a drawing context with HTMLCanvasElement.getContext(). Use of mozOpaque should be avoided. Firefox will stop supporting it in the future.

Syntax

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

Examples

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;

Specifications

Not part of any standard.

Browser compatibility

See also

• The interface defining it, HTMLCanvasElement.
• The moz-opaque HTML attribute of the <canvas> element.
• Optimizing your JavaScript game for Firefox OS