HTML5 Canvas getImageData安全错误

Question

HTML5 Canvas getImageData安全错误

May*_*sya 7 javascript html5 canvas cors html5-canvas

我想将彩色图像更改为灰度,但是当我尝试使用getImageData时出现安全性错误.

Uncaught SecurityError: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': The canvas has been tainted by cross-origin data.

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我知道这个错误已经到处讨论过,但没有一个有明确的解决方案.请帮忙!

<html>
<script>
function grayscale()
{
    var myCanvas = document.getElementById("c1");
    var myCanvasContext = myCanvas.getContext("2d");

    var img = document.getElementById("myImage");
    img.crossOrigin = "anonymous";

    var imgWidth = img.width;
    var imgHeight = img.height;

    myCanvas.width = imgWidth;
    myCanvas.height = imgHeight;

    myCanvasContext.drawImage(img,0,0);

    var imageData = myCanvasContext.getImageData(0,0, imgWidth, imgHeight);

    for (j=0; j<imageData.height; i++)
    {
            for (i=0; i<imageData.width; j++)
            {
                    var index=(i*4)*imageData.width+(j*4);
                    var red=imageData.data[index];
                    var green=imageData.data[index+1];
                    var blue=imageData.data[index+2];
                    var alpha=imageData.data[index+3];
                    var average=(red+green+blue)/3;
                    imageData.data[index]=average;
                    imageData.data[index+1]=average;
                    imageData.data[index+2]=average;
                    imageData.data[index+3]=alpha;
            }
    }
}
</script>
<body>
<img id="myImage" onload="grayscale()" src="doggie.png"></img>

<canvas id = "c1" width = "200px" height = "200px" style="border:1px solid #000000;">

</canvas>

</body>
</html>

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Answer 1

小智 2

最近我也有同样的问题。您必须在同一域（与您的代码）上拥有图像，或者在图像所在的服务器上设置跨域。

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