CanvasRenderingContext2D: globalCompositeOperation property
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.
Value
A string identifying which of the compositing or blending mode operations to use.
Operations
Examples
Changing the composite operation
This example uses the globalCompositeOperation
property to draw two
rectangles that exclude themselves where they overlap.
HTML
html
<canvas id="canvas"></canvas>
JavaScript
js
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 |
---|
HTML Standard # dom-context-2d-globalcompositeoperation-dev |
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 (Firefox 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