how to draw a imageUrl in Canvas?

Question

I am using html5 canvas with SignalR. I got the canvas Url By this,

var refreshCanvas = canvasParent.toDataURL();
whiteBoard.server.refreshCanvas(refreshCanvas);

I am getting data on client-side also, as a url string by:

whiteBoard.client.refreshCanvas = function (refreshCanvas){
    //alert(refreshCanvas);
    var img = new Image;
    img.onload = function () {
        contextParent.drawImage(img, 0, 0);
    };
    img.src = refreshCanvas;
}

I have checked that imagedata Url is coming as string but my problem is how to draw that imageUrl data onto my canvas.

my canvas name is "canvasParent" and context name is "contextParent".

I am getting image Url As :

data:image/png;base64,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That is not a URL. That is the binary representation of an image — jasonscript, Jul 09 '15 at 08:06
Possible duplicate of http://stackoverflow.com/questions/17879641/displaying-images-in-html5-canvas-from-binary-data — jasonscript, Jul 09 '15 at 08:08
img.src = dataURL; Maybe this helps: http://stackoverflow.com/questions/18976327/binary-array-to-canvas — Joep, Jul 09 '15 at 08:12
then what should i do to print that binary representation of an image into a canvas. @ jasonscript — , Jul 09 '15 at 08:17
What did you do? Only img.src = dataURL; won't work off coarse, you need some extra code to specify dataURL. Did you check the link? — Joep, Jul 09 '15 at 08:23
http://stackoverflow.com/questions/4773966/drawing-an-image-from-a-data-url-to-a-canvas — Joep, Jul 09 '15 at 08:29
whiteBoard.client.refreshCanvas = function (refreshCanvas) { var img = new Image; img.onload = function () { ctx.drawImage(img, 0, 0); // Or at whatever offset you like }; img.src = refreshCanvas; } — , Jul 09 '15 at 08:37
I simply want to show that imageUrl data in the canvas .,but that is not working. i am getting urldata on refreshCanvas .@jeop — , Jul 09 '15 at 08:38
So you are actually taking a snapshot of the canvas to draw it back to itself ? Why ? Ps: you are calling `whiteBoard.server.refreshCanvas();` but defined `whiteBoard.client.refreshCanvas();` maybe this is the issue. — Kaiido, Jul 10 '15 at 02:28
No I am working On signalR ,so whiteBoard.server.refreshCanvas(); and whiteBoard.client.refreshCanvas(); both are correct..@Kalido — , Jul 10 '15 at 11:16
Ok I don't know signalR nor ASP.net btw, but I assume that `contextParent` is `canvasParent`'s context. So you are actually drawing one canvas to itself. Also, if you are only defining `whiteBoard.client.refreshCanvas`, it seems really strange that `whiteBoard.server.refreshCanvas` got updated too. Except if `whiteBoard.client` and `whiteBoard.server` are actually two instances of the same object. — Kaiido, Jul 11 '15 at 10:48

how to draw a imageUrl in Canvas?

0 Answers0