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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 .putImageData() method of the Canvas 2D API paints data from the given ImageData object onto the canvas. If a dirty rectangle is provided, only the pixels from that rectangle are painted. This method is not affected by the canvas transformation matrix.

注意： Image data can be retrieved from a canvas using the getImageData() 方法。

You can find more information about putImageData() and general manipulation of canvas contents in the article Pixel manipulation with canvas .

句法

void ctx.putImageData(imageData, dx, dy);
void ctx.putImageData(imageData, dx, dy, dirtyX, dirtyY, dirtyWidth, dirtyHeight);
					

参数

imageData

ImageData object containing the array of pixel values.

dx

Horizontal position (x coordinate) at which to place the image data in the destination canvas.

dy

Vertical position (y coordinate) at which to place the image data in the destination canvas.

dirtyX 可选

Horizontal position (x coordinate) of the top-left corner from which the image data will be extracted. Defaults to 0 .

dirtyY 可选

Vertical position (y coordinate) of the top-left corner from which the image data will be extracted. Defaults to 0 .

dirtyWidth 可选

Width of the rectangle to be painted. Defaults to the width of the image data.

dirtyHeight 可选

Height of the rectangle to be painted. Defaults to the height of the image data.

Errors thrown

NotSupportedError

Thrown if any of the arguments is infinite.

InvalidStateError

Thrown if the ImageData object's data has been detached.

范例

Understanding putImageData

To understand what this algorithm does under the hood, here is an implementation on top of CanvasRenderingContext2D.fillRect() .

HTML

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

JavaScript

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
function putImageData(ctx, imageData, dx, dy,
    dirtyX, dirtyY, dirtyWidth, dirtyHeight) {
  var data = imageData.data;
  var height = imageData.height;
  var width = imageData.width;
  dirtyX = dirtyX || 0;
  dirtyY = dirtyY || 0;
  dirtyWidth = dirtyWidth !== undefined? dirtyWidth: width;
  dirtyHeight = dirtyHeight !== undefined? dirtyHeight: height;
  var limitBottom = dirtyY + dirtyHeight;
  var limitRight = dirtyX + dirtyWidth;
  for (var y = dirtyY; y < limitBottom; y++) {
    for (var x = dirtyX; x < limitRight; x++) {
      var pos = y * width + x;
      ctx.fillStyle = 'rgba(' + data[pos*4+0]
                        + ',' + data[pos*4+1]
                        + ',' + data[pos*4+2]
                        + ',' + (data[pos*4+3]/255) + ')';
      ctx.fillRect(x + dx, y + dy, 1, 1);
    }
  }
}
// Draw content onto the canvas
ctx.fillRect(0, 0, 100, 100);
// Create an ImageData object from it
var imagedata = ctx.getImageData(0, 0, 100, 100);
// use the putImageData function that illustrates how putImageData works
putImageData(ctx, imagedata, 150, 0, 50, 50, 25, 25);
					

结果

Data loss due to browser optimization

Due to the lossy nature of converting to and from premultiplied alpha color values, pixels that have just been set using putImageData() might be returned to an equivalent getImageData() as different values.

JavaScript

const canvas = document.createElement("canvas");
canvas.width = 1;
canvas.height = 1;
const context = canvas.getContext("2d");
const imgData = context.getImageData(0, 0, canvas.width, canvas.height);
const pixels = imgData.data;
pixels[0 + 0] = 1;
pixels[0 + 1] = 127;
pixels[0 + 2] = 255;
pixels[0 + 3] = 1;
console.log("before:", pixels);
context.putImageData(imgData, 0, 0);
const imgData2 = context.getImageData(0, 0, canvas.width, canvas.height);
const pixels2 = imgData2.data;
console.log("after:", pixels2);
					

The output might look like:

before: Uint8ClampedArray(4) [ 1, 127, 255, 1 ]
after: Uint8ClampedArray(4) [ 255, 255, 255, 1 ]
					

规范

规范	状态	注释
HTML 实时标准 The definition of 'CanvasRenderingContext2D.putImageData' 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
putImageData	Chrome Yes	Edge 12	Firefox 2	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

图例

完整支持

完整支持

Gecko-specific notes

• Starting in Gecko 10.0 (Firefox 10.0 / Thunderbird 10.0 / SeaMonkey 2.7), non-finite values to any of these parameters cause the call to putImageData() to be silently ignored, rather than throwing an exception.
• To comply with the specification, starting with Gecko 16.0 (Firefox 16.0 / Thunderbird 16.0 / SeaMonkey 2.13), a call with an invalid number of arguments (only 3 or 7 arguments are valid), will now throw an error ( bug 762657 ).

另请参阅

• The interface defining this method: CanvasRenderingContext2D
• ImageData 对象
• CanvasRenderingContext2D.getImageData()
• Pixel manipulation with canvas

元数据

• 最后修改： Apr 14, 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()