Web/API/CanvasRenderingContext2D/setTransform

The CanvasRenderingContext2D.setTransform() method of the Canvas 2D API resets (overrides) the current transformation to the identity matrix, and then invokes a transformation described by the arguments of this method. This lets you scale, rotate, translate (move), and skew the context.

Note: See also the transform() method; instead of overriding the current transform matrix, it multiplies it with a given one.

Syntax

ctx.setTransform(a, b, c, d, e, f);
ctx.setTransform(matrix);

The transformation matrix is described by: <math display="inline">\begin{bmatrix} a & c & e \\ b & d & f \\ 0 & 0 & 1 \\ \end{bmatrix}</math>

Parameters

setTransform() has two types of parameter that it can accept. The older type consists of several parameters representing the individual components of the transformation matrix to set:

a (m11): Horizontal scaling. A value of 1 results in no scaling.
b (m12): Vertical skewing.
c (m21): Horizontal skewing.
d (m22): Vertical scaling. A value of 1 results in no scaling.
e (dx): Horizontal translation (moving).
f (dy): Vertical translation (moving).

The newer type consists of a single parameter, matrix, representing a 2D transformation matrix to set (technically, a DOMMatrixInit object; any object will do as long as it contains the above components as properties).

Examples

Skewing a shape

This example skews a rectangle both vertically (.2) and horizontally (.8). Scaling and translation remain unchanged.

HTML

<canvas id="canvas"></canvas>

JavaScript

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

ctx.setTransform(1, .2, .8, 1, 0, 0);
ctx.fillRect(0, 0, 100, 100);

Result

Retrieving and passing a DOMMatrix object

In the following example, we have two <canvas> elements. We apply a transform to the first one's context using the first type of setTransform() and draw a square on it, then retrieve the matrix from it using CanvasRenderingContext2D.getTransform().

We then apply the retrieved matrix directly to the second canvas context by passing the DOMMatrix object directly to setTransform() (i.e. the second type), and draw a circle on it.

HTML

<canvas width="240"></canvas>
<canvas width="240"></canvas>

CSS

canvas {
  border: 1px solid black;
}

JavaScript

const canvases = document.querySelectorAll('canvas');
const ctx1 = canvases[0].getContext('2d');
const ctx2 = canvases[1].getContext('2d');

ctx1.setTransform(1, .2, .8, 1, 0, 0);
ctx1.fillRect(25, 25, 50, 50);

let storedTransform = ctx1.getTransform();
console.log(storedTransform);

ctx2.setTransform(storedTransform);
ctx2.beginPath();
ctx2.arc(50, 50, 50, 0, 2 * Math.PI);
ctx2.fill();

Result

Specifications

Specification	Status	Comment
HTML Living StandardThe definition of 'CanvasRenderingContext2D.setTransform' in that specification.	Living Standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`setTransform`	Chrome Full support Yes	Edge Full support 12	Firefox Full support 3	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 4	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
Accept matrix object as parameter	Chrome Full support 68	Edge Full support 79	Firefox Full support 70	IE No support No	Opera Full support 55	Safari Full support 11	WebView Android Full support 68	Chrome Android Full support 68	Firefox Android No support No	Opera Android Full support 48	Safari iOS Full support 11	Samsung Internet Android Full support 10.0

Legend

Full support: Full support
No support: No support