The
CanvasRenderingContext2D
.globalCompositeOperation
property of the Canvas 2D API sets the type of compositing operation to apply when
drawing new shapes.
See also Compositing and clipping in the Canvas Tutorial.
Syntax
ctx.globalCompositeOperation = type;
type
is a String
identifying which of the compositing or
blending mode operations to use.
Types
Examples
Changing the composite operation
This example uses the globalCompositeOperation
property to draw two
rectangles that exclude themselves where they overlap.
HTML
<canvas id="canvas"></canvas>
JavaScript
const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
ctx.globalCompositeOperation = 'xor';
ctx.fillStyle = 'blue';
ctx.fillRect(10, 10, 100, 100);
ctx.fillStyle = 'red';
ctx.fillRect(50, 50, 100, 100);
Result
Specifications
Specification | Status | Comment |
---|---|---|
HTML Living Standard The definition of 'CanvasRenderingContext2D.globalCompositeOperation' in that specification. |
Living Standard | |
Compositing and Blending Level 1 | Candidate Recommendation |
Browser compatibility
BCD tables only load in the browser
WebKit/Blink-specific notes
- In WebKit- and Blink-based Browsers, a non-standard and deprecated method
ctx.setCompositeOperation()
is implemented besides this property. - Support for
"plus-darker"
and"darker"
were removed in Chrome 48. Developers looking for a replacement should use"darken"
.
Gecko-specific notes
- An early Canvas specification draft specified the value
"darker"
. However, Firefox removed support for"darker"
in version 4 (bug 571532). See also this blog post that suggests using"difference"
as a way to achieve a similar affect to"darker"
.
See also
- The interface defining this property:
CanvasRenderingContext2D
CanvasRenderingContext2D.globalAlpha