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HTMLCanvasElement: mozOpaque property

files/en-us/web/api/htmlcanvaselement/mozopaque/index.md

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{{APIRef("Canvas API")}}{{deprecated_header}}{{non-standard_header}}

The non-standard HTMLCanvasElement.mozOpaque property is a boolean value reflecting the moz-opaque HTML attribute of the {{HTMLElement("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 {{domxref("HTMLCanvasElement.getContext()")}}. Use of mozOpaque should be avoided. Firefox will stop supporting it in the future.

Value

A boolean value.

Examples

Given this {{HTMLElement("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

{{Compat}}

See also