jQuery File Upload 判断图片尺寸，限定图片宽高的办法

1.必须熟读jQuery File Upload 文档，在add方法中进行判断，如果不符合条件，就用 data.abort()方法取消上传动作。

$("file").fileupload({...}).on('fileuploadadd', function (e, data) {
        var files=data.files;
            if(navigator.userAgent.indexOf("MSIE 8.0")>0 || navigator.userAgent.indexOf("MSIE 9.0")>0){
                var objPreviewSizeFake = $('<img style="filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);width:300px;visibility:hidden;"  />').appendTo('body').getDOMNode();
                objPreviewSizeFake.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
                //var objPreviewSizeFake = $(".conImage").get(0);//jquery对象转化为DOM对象
                var fileupload = document.getElementById("head");
                var $fileupload = $(fileupload);
                $fileupload.select();
                $fileupload.blur();
                path = document.selection.createRange().text;

                if (/"\w\W"/.test(path)) {
                    path = path.slice(1,-1);
                }

                objPreviewSizeFake.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = path;
                width_${fileInputId}=objPreviewSizeFake.offsetWidth;
                height_${fileInputId}=objPreviewSizeFake.offsetHeight;
                if(width_${fileInputId}> 800 || height_${fileInputId}> 800){
                    alert("上传的图片的宽和高都不能超过800px，当前图片高度"+width_${fileInputId}+"px,宽度"+height_${fileInputId}+"px，请裁剪后再上传。否则无法通过审核噢。");
                    data.abort();
                }
                document.selection.empty();
            }else{
                for (var i = 0; i < files.length; i++) {
                    var file = files[i];
                    var reader = new FileReader();
                    var ret = [];
                    reader.onload = function(theFile) {
                        var image = new Image();
                        image.onload = function() {
                            width_${fileInputId}=this.width;
                            height_${fileInputId}=this.height;
                            if(width_${fileInputId}> 800 || height_${fileInputId}> 800){
                                alert("上传的图片的宽和高都不能超过800px，当前图片高度"+width_${fileInputId}+"px,宽度"+height_${fileInputId}+"px，请裁剪后再上传。否则无法通过审核噢。");
                                data.abort();
                            }
                        };
                        image.src = theFile.target.result;
                    }
                    reader.readAsDataURL(file);
                }
            }
    })

2.参考：

http://www.imooc.com/article/12798