CanvasRenderingContext2D.transform()

The CanvasRenderingContext2D.transform() method of the Canvas 2D API multiplies the current transformation with the matrix described by the arguments of this method. You are able to scale, rotate, move and skew the context.

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

SyntaxEdit

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.

b (m12)

Horizontal skewing.

c (m21)

Vertical skewing.

d (m22)

Vertical scaling.

e (dx)

Horizontal moving.

f (dy)

Vertical moving.

ExamplesEdit

Using the transform method

This is just a simple code snippet which uses the transform method.

HTML

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

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

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

Edit the code below and see your changes update live in the canvas:

<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
  <input id="edit" type="button" value="Edit" />
  <input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code">
ctx.transform(1,1,0,1,0,0);
ctx.fillRect(0,0,100,100);</textarea>

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;

function drawCanvas() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  eval(textarea.value);
}

reset.addEventListener("click", function() {
  textarea.value = code;
  ctx.setTransform(1, 0, 0, 1, 0, 0);
  drawCanvas();
});

edit.addEventListener("click", function() {
  textarea.focus();
})

textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);

SpecificationsEdit

Browser compatibilityEdit

See alsoEdit

• The interface defining it, CanvasRenderingContext2D
• CanvasRenderingContext2D.setTransform()