CanvasRenderingContext2D.createPattern()
The
CanvasRenderingContext2D.createPattern()
method of the Canvas 2D API creates a pattern using the specified image and repetition.
This method returns a CanvasPattern
.
This method doesn't draw anything to the canvas directly. The pattern it creates must
be assigned to the CanvasRenderingContext2D.fillStyle
or
CanvasRenderingContext2D.strokeStyle
properties, after which it is
applied to any subsequent drawing.
Syntax
CanvasPattern ctx.createPattern(image, repetition);
Parameters
image
-
A
CanvasImageSource
to be used as the pattern's image. It can be any of the following:HTMLImageElement
(<img>
)SVGImageElement
(<image>
)-
HTMLVideoElement
(<video>
, by using the capture of the video) HTMLCanvasElement
(<canvas>
)ImageBitmap
OffscreenCanvas
repetition
-
A
DOMString
indicating how to repeat the pattern's image. Possible values are:"repeat"
(both directions)"repeat-x"
(horizontal only)"repeat-y"
(vertical only)"no-repeat"
(neither direction)
If
repetition
is specified as an empty string (""
) ornull
(but notundefined
), a value of"repeat"
will be used.
Return value
CanvasPattern
-
An opaque object describing a pattern.
Examples
Creating a pattern from an image
This example uses the createPattern()
method to create a
CanvasPattern
with a repeating source image. Once created, the pattern is
assigned to the canvas context's fill style and applied to a rectangle.
The original image looks like this:
HTML
<canvas id="canvas" width="300" height="300"></canvas>
JavaScript
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var img = new Image();
img.src = 'canvas_createpattern.png';
img.onload = function() {
var pattern = ctx.createPattern(img, 'repeat');
ctx.fillStyle = pattern;
ctx.fillRect(0, 0, 300, 300);
};
Creating a pattern from a canvas
In this example we create a pattern from the contents of an offscreen canvas. We then apply it to the fill style of our primary canvas, and fill that canvas with the pattern.
JavaScript
// Create a pattern, offscreen
const patternCanvas = document.createElement('canvas');
const patternContext = patternCanvas.getContext('2d');
// Give the pattern a width and height of 50
patternCanvas.width = 50;
patternCanvas.height = 50;
// Give the pattern a background color and draw an arc
patternContext.fillStyle = '#fec';
patternContext.fillRect(0, 0, patternCanvas.width, patternCanvas.height);
patternContext.arc(0, 0, 50, 0, .5 * Math.PI);
patternContext.stroke();
// Create our primary canvas and fill it with the pattern
const canvas = document.createElement('canvas');
const ctx = canvas.getContext('2d');
const pattern = ctx.createPattern(patternCanvas, 'repeat');
ctx.fillStyle = pattern;
ctx.fillRect(0, 0, canvas.width, canvas.height);
// Add our primary canvas to the webpage
document.body.appendChild(canvas);
Result
Specifications
Specification |
---|
HTML Standard # dom-context-2d-createpattern-dev |
Browser compatibility
BCD tables only load in the browser
Gecko-specific notes
-
Starting with Gecko 5.0 (Firefox 5.0 / Thunderbird 5.0 / SeaMonkey 2.2), specifying a
null
orundefined
image correctly throws aTYPE_MISMATCH_ERR
exception. -
Starting with Gecko 16.0 (Firefox 16.0 / Thunderbird 16.0 / SeaMonkey 2.13), specifying
null
for therepetition
parameter is now allowed and results in the repetition being set to"repeat"
(bug 762657).
See also
- The interface defining this method:
CanvasRenderingContext2D
CanvasPattern