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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

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.

注意： 另请参阅 transform() method; instead of overriding the current transform matrix, it multiplies it with a given one.

句法

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

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

参数

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).

范例

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);
					

结果

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();
					

结果

规范

规范	状态	注释
HTML 实时标准 The definition of 'CanvasRenderingContext2D.setTransform' in that specification.	实时标准

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	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 Yes	Edge 12	Firefox 3	IE Yes	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android 4	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes
Accept matrix object as parameter	Chrome 68	Edge 79	Firefox 70	IE No	Opera 55	Safari 11	WebView Android 68	Chrome Android 68	Firefox Android No	Opera Android 48	Safari iOS 11	Samsung Internet Android 10.0

图例

完整支持

完整支持

不支持

不支持

另请参阅

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

元数据

• 最后修改： Sep 13, 2019

相关话题

1. CanvasRenderingContext2D
2. 特性

   1. canvas
   2. currentTransform
   3. direction
   4. fillStyle
   5. filter
   6. font
   7. globalAlpha
   8. globalCompositeOperation
   9. imageSmoothingEnabled
   10. imageSmoothingQuality
   11. lineCap
   12. lineDashOffset
   13. lineJoin
   14. lineWidth
   15. miterLimit
   16. shadowBlur
   17. shadowColor
   18. shadowOffsetX
   19. shadowOffsetY
   20. strokeStyle
   21. textAlign
   22. textBaseline
3. 方法

   1. addHitRegion()
   2. arc()
   3. arcTo()
   4. beginPath()
   5. bezierCurveTo()
   6. clearHitRegions()
   7. clearRect()
   8. clip()
   9. closePath()
   10. createImageData()
   11. createLinearGradient()
   12. createPattern()
   13. createRadialGradient()
   14. drawFocusIfNeeded()
   15. drawImage()
   16. drawWidgetAsOnScreen()
   17. drawWindow()
   18. ellipse()
   19. fill()
   20. fillRect()
   21. fillText()
   22. getImageData()
   23. getLineDash()
   24. getTransform()
   25. isPointInPath()
   26. isPointInStroke()
   27. lineTo()
   28. measureText()
   29. moveTo()
   30. putImageData()
   31. quadraticCurveTo()
   32. rect()
   33. removeHitRegion()
   34. resetTransform()
   35. restore()
   36. rotate()
   37. save()
   38. scale()
   39. scrollPathIntoView()
   40. setLineDash()
   41. setTransform()
   42. stroke()
   43. strokeRect()
   44. strokeText()
   45. transform()
   46. translate()