previewImage.js //图片上传预览 IE是用了滤镜。 <input type="file" id="upload_file" value="" name="car_loaction1" onchange="previewImage(this)"> <a class="thumbnail" href="#" id="preview"> <img alt="" src="http://placehold.it/160x120"> </a>

gistfile1.txt

 
  //图片上传预览    IE是用了滤镜。
function previewImage(file)
{
 var MAXWIDTH  = 260; 
 var MAXHEIGHT = 180;
 var div = document.getElementById('preview');
 if (file.files && file.files[0])
 {
     div.innerHTML ='<img id=imghead>';
     var img = document.getElementById('imghead');
     img.onload = function(){
       var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
       img.width  =  rect.width;
       img.height =  rect.height;
//        img.style.marginLeft = rect.left+'px';
       img.style.marginTop = rect.top+'px';
     }
     var reader = new FileReader();
     reader.onload = function(evt){img.src = evt.target.result;}
     reader.readAsDataURL(file.files[0]);
 }
 else //兼容IE
 {
   var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
   file.select();
   var src = document.selection.createRange().text;
   div.innerHTML = '<img id=imghead>';
   var img = document.getElementById('imghead');
   img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
   var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
   status =('rect:'+rect.top+','+rect.left+','+rect.width+','+rect.height);
   div.innerHTML = "<div id=divhead style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;"+sFilter+src+"\"'></div>";
 }
}
function clacImgZoomParam( maxWidth, maxHeight, width, height ){
   var param = {top:0, left:0, width:width, height:height};
   if( width>maxWidth || height>maxHeight )
   {
       rateWidth = width / maxWidth;
       rateHeight = height / maxHeight;
       
       if( rateWidth > rateHeight )
       {
           param.width =  maxWidth;
           param.height = Math.round(height / rateWidth);
       }else
       {
           param.width = Math.round(width / rateHeight);
           param.height = maxHeight;
       }
   }
   
   param.left = Math.round((maxWidth - param.width) / 2);
   param.top = Math.round((maxHeight - param.height) / 2);
   return param;
}