Convert canvas to an image with JavaScript [duplicate]

Question

I want to convert canvas to an image with JavaScript, When I try to canvas.toDataURL("image/png"); It gives the following error

SecurityError: The operation is insecure

Answer 1

You have the right idea, and it will work in very simple cases such as:

var can = document.getElementById('canvas1');
var ctx = can.getContext('2d');

ctx.fillRect(50,50,50,50);

var img = new Image();
img.src = can.toDataURL();
document.body.appendChild(img);

http://jsfiddle.net/simonsarris/vgmFN/

But it becomes problematic if you have "dirtied" your canvas. This is done by drawing images to the canvas that are from a different origin. For instance, if your canvas is hosted at www.example.com, and you use images from www.wikipedia.org, then your canvas' origin-clean flag is set to false internally.

Once the origin-clean flag is set to false, you are no longer allowed to call toDataURL or getImageData

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Technically, images are of the same origin if domains, protocols, and ports match.

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If you are working locally (file://) then any image drawn will set off the flag. This makes debugging annoying, but with Chrome you can start it with the flag --allow-file-access-from-files to allow this.