Why does canvas.toDataURL() throw a security exception?

javascript html canvas cross-domain
pop850 picture pop850 · Mar 5, 2010 · Viewed 70.6k times · Source

Did I not get enough sleep or what? This following code

var frame=document.getElementById("viewer");
frame.width=100;
frame.height=100;

var ctx=frame.getContext("2d");
var img=new Image();
img.src="http://www.ansearch.com/images/interface/item/small/image.png"

img.onload=function() {
    // draw image
    ctx.drawImage(img, 0, 0)

    // Here's where the error happens:
    window.open(frame.toDataURL("image/png"));
}

is throwing this error: 

SECURITY_ERR: DOM Exception 18

There's no way this shouldn't work! Can anyone explain this, please?

Answer

Bob picture Bob · Mar 5, 2010

In the specs it says:

Whenever the toDataURL() method of a canvas element whose origin-clean flag is set to false is called, the method must raise a SECURITY_ERR exception.

If the image is coming from another server I don't think you can use toDataURL()

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