HTMLCanvasElement: mozOpaque property

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Non-standard: This feature is not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

The non-standard HTMLCanvasElement.mozOpaque property is a boolean value 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.

Note: 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.

Value

A boolean value.

Examples

Given this <canvas> element:

html
<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.

js
const canvas = document.getElementById("canvas");
console.log(canvas.mozOpaque); // true
// deactivate it
canvas.mozOpaque = false;

Specifications

Not part of any standard.

Browser compatibility

See also