Question

我将此作为我的源画布

HTML

 <h1>Source Canvas</h1>
 <canvas id="source" width=436 height=567></canvas>
 <h1>Destination Canvas</h1>
 <canvas id="destination" width=436 height=567></canvas>

的javascript

 var sourceImage, ctx, sourceCanvas, destinationCanvas;
        //get the canvases
        sourceCanvas = document.getElementById('source');
        destinationCanvas = document.getElementById('destination');

    //draw the source image to the source canvas
    ctx = sourceCanvas.getContext('2d');

     function start() {

                ctx.drawImage(img1, 0, 0);

                ctx.globalCompositeOperation = "source-atop";

                var pattern = ctx.createPattern(img, 'repeat');
                ctx.rect(0, 0, sourceCanvas.width, sourceCanvas.height);
                ctx.fillStyle = pattern;
                ctx.fill();

                ctx.globalAlpha = .10;
                ctx.drawImage(img1, 0, 0);
                ctx.drawImage(img1, 0, 0);
                ctx.drawImage(img1, 0, 0);
                 //ctx.globalAlpha = 1;
            }
     var img1 = new Image();
     var img = new Image();
    img.onload = function () {

              img1.onload = function () {
                  start();
              }
img1.src = "https://dl.dropboxusercontent.com/u/139992952/stackoverflow/4jiSz1.png";
}
img.src = "https://dl.dropboxusercontent.com/u/139992952/stackoverflow/BooMu1.png";

我想在目标画布中显示源画布中的内容。

我累了

var image, destinationCtx;

//create the image
image = new Image();

//get the base64 data
image.src = sourceCanvas.toDataURL('image/png');

//get the destination context
destinationCtx = destinationCanvas.getContext('2d');

//copy the data
destinationCtx.drawImage(image, 0, 0);

//done

但没有运气。我错过了什么吗？通过imageData复制，通过Base64数据复制，通过直接绘制复制任何方法都可以完成我的工作。当我尝试

http://jsperf.com/copying-a-canvas-element 它复制，但当我把我的源画布作家它不起作用？我错过了什么吗？

Answer 1

您可以直接将一个画布复制到另一个画布上。像这样......

var destinationCtx;

//get the destination context
destinationCtx = destinationCanvas.getContext('2d');

//copy the data
destinationCtx.drawImage(sourceCanvas, 0, 0);

Answer 2

您可以使用源画布中的getImageData和putImageData到目标画布。与其他方式相比，这是最快的。

var sourceCtx, destinationCtx, imageData;

sourceCtx = sourceCanvas.getContext('2d');
destinationCtx = destinationCanvas.getContext('2d');

imageData = sourceCtx.getImageData(0, 0, sourceCanvas.width - 1, sourceCanvas.height - 1);

destinationCtx.putImageData(imageData, 0, 0);

来源：/ https://jsperf.com/copying-a-canvas-element

如何从一个画布复制到其他画布

2 个答案: