CanvasRenderingContext2D.transform() - Web APIs 编辑

The CanvasRenderingContext2D.transform() method of the Canvas 2D API multiplies the current transformation with the matrix described by the arguments of this method. This lets you scale, rotate, translate (move), and skew the context.

Note: See also the setTransform() method, which resets the current transform to the identity matrix and then invokes transform().

Syntax

void ctx.transform(a, b, c, d, e, f);

The transformation matrix is described by: $\left[ \begin{array}{ccc} a & c & e \\ b & d & f \\ 0 & 0 & 1 \end{array} \right]$

Parameters

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).

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

Result

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• The interface defining this method: CanvasRenderingContext2D
• CanvasRenderingContext2D.setTransform()