javascript - How to compare content of two html5-canvas-elements? - Stack Overflow

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I would like to pare two images with javascript. One is drawn on a html5 canvas the other might be on another html5 canvas, or it might be a gif- or png-image-file. I need the parision for automated testing. Thanks for help!

I would like to pare two images with javascript. One is drawn on a html5 canvas the other might be on another html5 canvas, or it might be a gif- or png-image-file. I need the parision for automated testing. Thanks for help!

• javascript
• html5-canvas

Share Improve this question Follow asked Dec 1, 2011 at 12:59 user1027167user1027167 4,45877 gold badges3535 silver badges4141 bronze badges

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Sorted by: Reset to default 10

alright this isn't a plete solution for your problem but it might help you find a good way to pare the two canvas elements.

var ctx = canvas.getContext('2d');
var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
var pixels = imageData.data;

for(var i = 0, il = pixels.length; i < il; i++) {
    // pixels[i]
}

This is a basic example how to loop through all the pixels on the canvas. Depending on what you want to do you can pare the pixels with each other or you might want to pare the two imageData vars with each other

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