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POStoring HTML5 canvas containing images
 

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  1. POStoring HTML5 canvas containing images
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    <p>How do you store a canvas that contains images using the toDataURL method? Everything works fine for text and drawing, but I don't know how to handle images. Any help would be appreciated. Thanks</p> <p>I have modified my question as follows: </p> <p>This works when the image is pulled directly from a .png. However, when I call the Google Charts API, toDataURL doesn't work even though the image renders correctly on the canvas. Google Charts is returning a .png. Anyone have any ideas? Thanks.</p> <pre><code>&lt;!DOCTYPE HTML&gt; &lt;html&gt; &lt;head&gt; &lt;meta charset="utf-8"&gt; &lt;script type="text/javascript" charset="utf-8"&gt; function test() { var c = document.getElementById("drawing-canvas"); var cxt = c.getContext("2d"); // This doesn't work. //var imgsrc = 'http://chart.apis.google.com/chart?cht=tx&amp;chf=bg,s,ffffff&amp;chco=000000&amp; chl=a'; // This works var imgsrc = 'chart.png'; var img = new Image(); img.src = imgsrc; cxt.drawImage(img,0,0); } function wr() { var cc = document.getElementById("drawing-canvas"); var url = cc.toDataURL(); var newImg = document.createElement("img"); newImg.src = url; document.body.appendChild(newImg); } &lt;/script&gt; &lt;/head&gt; &lt;body onload = "test();"&gt; &lt;canvas id="drawing-canvas" width = "500px" height = "500px" style="background-color: #ffffff; border: 2px solid #000000;"&gt; Your browser does not support the canvas element. &lt;/canvas&gt; &lt;input type = "button" value = "go" onclick = "wr();"&gt; &lt;/body&gt; &lt;/html&gt; </code></pre>
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    1. COWhen I use drawImage on the canvas and the source is a .png everything works fine. When I use an image obtained from the Google Charts API it renders correctly in the canvas, but I can't save it with toDataURL.
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    2. COYes, thanks, this worked when I saved the image on the server. I am having problems with caching though. I tried img.src = "chart.png' + '?' + Math.random(); but drawImage(img,x,y) doesn't work for some reason. However, it does work when I construct img.src = 'chart.png?12345'. Any ideas?
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