image,onload event not working in chrome

Early73 picture Early73 · Apr 28, 2011 · Viewed 24.2k times · Source

I'm using html5 to create drag and drop image upload functionality. This works great for me in firefox but in chrome the image onload event only fires the first time. If I drag multiple images in only the first works and if I drag a second in it fails. I believe the problem is with the image onload.

here is the way my code works I have removed the irrelevant sections:

            var img = document.createElement("img");
            var reader = new FileReader();
            var canvas = document.createElement("canvas");
            var canvasData;
            var ctx = canvas.getContext("2d");
            var myFiles;
            var i = 0; 


                 reader.onload = (function (aImg)
                    { 
                        return function (e)
                        {
                            aImg.src = e.target.result;
                        };
                    })(img);

        img.onload = function (){

        //resizes image 
        //draws it to the canvas
        //posts to server

        i++;
        if(i < myFiles.length){
        processNext(i);
                            }
        }



    function processNext(filei) {

         var file = myFiles[filei];

            img.file = file;

            reader.readAsDataURL(file);


        }

i = 0;
myFiles = files;
processNext(0);

Does anyone know why this works in firefox but not chrome?

Answer

Harut picture Harut · Apr 28, 2011

Explanation from chromium tracker:

This is not a bug. WebKit is just more strict. You must instantiate a new Image() object before the replacement, like this:

var photo = document.getElementById('image_id');
var img = new Image();
img.addEventListener('load', myFunction, false);
img.src = 'http://newimgsource.jpg';
photo.src = img.src;

source: http://code.google.com/p/chromium/issues/detail?id=7731#c12