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Object does not support this property or method IE8

I am using this HTML5 grayscialer code - http://webdesignerwall.com/demo/html5-grayscale/ However, in the javascript, IE8 returns the error "Object does not support this property or method." Does anybody know whats wrong with the JavaScript? I'm pretty sure this line right here is causing the error "var ctx = canvas.getContext('2d');" Thanks.

// $(".item img").css({"display":"none");

// On window load. This waits until images have loaded which is essential
$(window).load(function(){

    // Fade in images so there isn't a color "pop" document load and then on window load
    $(".item img").animate({opacity:1},500);

    // clone image
    $('.item img').each(function(){
        var el = $(this);
        el.css({"position":"absolute"}).wrap("<div class='img_wrapper' style='display: inline-block'>").clone().addClass('img_grayscale').css({"position":"absolute","z-index":"998","opacity":"0"}).insertBefore(el).queue(function(){
            var el = $(this);
            el.parent().css({"width":this.width,"height":this.height});
            el.dequeue();
        });
        this.src = grayscale(this.src);
    });

    // Fade image 
    $('.item img').mouseover(function(){
        $(this).parent().find('img:first').stop().animate({opacity:1}, 1000);
    })
    $('.img_grayscale').mouseout(function(){
        $(this).stop().animate({opacity:0}, 1000);
    });     
});

// Grayscale w canvas method
function grayscale(src){
    var canvas = document.createElement('canvas');
    var ctx = canvas.getContext('2d');
    var imgObj = new Image();
    imgObj.src = src;
    canvas.width = imgObj.width;
    canvas.height = imgObj.height; 
    ctx.drawImage(imgObj, 0, 0); 
    var imgPixels = ctx.getImageData(0, 0, canvas.width, canvas.height);
    for(var y = 0; y < imgPixels.height; y++){
        for(var x = 0; x < imgPixels.width; x++){
            var i = (y * 4) * imgPixels.width + x * 4;
            var avg = (imgPixels.data[i] + imgPixels.data[i + 1] + imgPixels.data[i + 2]) / 3;
            imgPixels.data[i] = avg; 
            imgPixels.data[i + 1] = avg; 
            imgPixels.data[i + 2] = avg;
        }
    }
    ctx.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height);
    return canvas.toDataURL();
}
like image 368
henryaaron Avatar asked Dec 04 '22 05:12

henryaaron


2 Answers

Internet Explorer version 8 and earlier do not support the canvas element.

like image 86
u.k Avatar answered Dec 17 '22 08:12

u.k


If you want to use canvas on IE8 you will need to look into Google's excanvas. Check it out here: http://code.google.com/p/explorercanvas/wiki/Instructions

like image 45
PriorityMark Avatar answered Dec 17 '22 08:12

PriorityMark