Poor performance of html5 canvas under firefox

Question

I have the following html5 code:

<canvas id="myCanvas" width=600 height=600>
</canvas>

followed by some javascript:

<script type="text/javascript">
<!--
    var img = new Image();
    img.addEventListener('load', function()
    {
        reDraw('', this);
    }, false);

    img.src = "wood.png";

    function reDraw(canv, image)
        {
        var canvas = canv;
        if (canvas == '')
        {
            canvas = $("canvas");
        }

        var size = canvas.attr("width");
        var elem = canvas.get(0);

        if (!elem || !elem.getContext){
            return;
        }

        var context = elem.getContext('2d');
        if (!context || !context.drawImage)
            {
            return;
        }

        context.drawImage(image, 0, 0, size, size);
    };


    window.onresize = function() {
        var size = window.innerWidth;
        if (window.innerHeight < size)
        {
            size = window.innerHeight;
        };
        size = size/2;

        $("canvas").each(function()
        {
            $(this).attr({width: size, height: size});
            reDraw($(this), img);
        });
    };

// -->
</script>

Now the problem is that under Chrome this code works smoothly, but under FireFox (3.6.15) when I resize the window, then it takes a while to work. What can be the problem? And how to fix it, so it would also work smoothly under FF?

Answer 1

Firefox's drawImage function has poor performance

You might want to consider adding a setTimeout function in the onresize to prevent it from trying to redraw while the user is dragging the window to improve performance.