CanvasRenderingContext2D.setTransform()

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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: [acebdf001]\left[ \begin{array}{ccc} a & c & e \\ b & d & f \\ 0 & 0 & 1 \end{array} \right]

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 Standard
The definition of 'CanvasRenderingContext2D.setTransform' in that specification.
Living Standard

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
setTransformChrome Full support YesEdge Full support 12Firefox Full support 3IE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes
Accept matrix object as parameterChrome Full support 68Edge No support NoFirefox Full support 70IE No support NoOpera Full support 55Safari Full support 11WebView Android Full support 68Chrome Android Full support 68Firefox Android No support NoOpera Android Full support 48Safari iOS Full support 11Samsung Internet Android No support No

Legend

Full support  
Full support
No support  
No support

See also