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javascript - Save HTML5 canvas with images as an image - Stack Overflow

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I'm trying to save a canvas with images to PNG, but when I try this:

var myCanvas = document.getElementById("myCanvas");
var img = document.createElement('img');
var ctx = myCanvas.getContext ? myCanvas.getContext('2d') : null;
img.src = 'image.png';

img.onload = function () {  
    ctx.drawImage(img, 0, 0, myCanvas.width, myCanvas.height);
}

var data = myCanvas.toDataURL("image/png");
if (!window.open(data)) {
    document.location.href = data;
}

I only get a blank transparent image without the image. What am I doing wrong?

I'm trying to save a canvas with images to PNG, but when I try this:

var myCanvas = document.getElementById("myCanvas");
var img = document.createElement('img');
var ctx = myCanvas.getContext ? myCanvas.getContext('2d') : null;
img.src = 'image.png';

img.onload = function () {  
    ctx.drawImage(img, 0, 0, myCanvas.width, myCanvas.height);
}

var data = myCanvas.toDataURL("image/png");
if (!window.open(data)) {
    document.location.href = data;
}

I only get a blank transparent image without the image. What am I doing wrong?

Share Improve this question edited May 22, 2014 at 12:23 famousgarkin 14.1k5 gold badges59 silver badges74 bronze badges asked Sep 27, 2012 at 11:52 JaapJaap 1691 gold badge4 silver badges9 bronze badges
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1 Answer 1

Reset to default 6

You need to put the window.open call in the load handler since this happens asynchronously.

img.onload = function () {  
    ctx.drawImage(img, 0, 0, myCanvas.width, myCanvas.height);

    var data = myCanvas.toDataURL("image/png");
    if (!window.open(data)) {
        document.location.href = data;
    }
}
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