图片上传本地预览兼容ie8-原创手记-慕课网

工作中遇到的，总结下来了，图片上传本地预览限制图片最大为2M
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >

<head>     
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />     
<title>图片上传本地预览</title>     
<style type="text/css">
#preview1{width:260px;height:190px;border:1px solid #000;overflow:hidden;}
#imghead1 {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}
#preview2{width:260px;height:190px;border:1px solid #000;overflow:hidden;}
#imghead2 {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}
#preview3{width:260px;height:190px;border:1px solid #000;overflow:hidden;}
#imghead3 {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);}
</style>
<script type="text/javascript">
      //图片上传预览    IE是用了滤镜。
        function previewImage1(file)
        {
          var MAXWIDTH  = 260; 
          var MAXHEIGHT = 180;
          var div = document.getElementById('preview1');
          if (file.files && file.files[0])
          {
              div.innerHTML ='<img id=imghead1>';
              var img = document.getElementById('imghead1');
              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();
            file.blur();
            var src = document.selection.createRange().text;
            div.innerHTML = '<img id=imghead1>';
            var img = document.getElementById('imghead1');
            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;
        }
        function getPhotoSize1(obj){
        var fileSize = 0;
        var isIE = /msie/i.test(navigator.userAgent) && !window.opera;      
        if (isIE && !obj.files) {     
           fileSize = file.Size;     
        }else { 
           fileSize = obj.files[0].size;   
        } 
        fileSize=Math.round(fileSize/1024*100)/100; //单位为KB
        if(fileSize>=2048){
          alert("照片最大尺寸为2MB，请重新上传!");
        }else{
          previewImage1(obj);
        }
      }
</script>    
<script type="text/javascript">
      //图片上传预览    IE是用了滤镜。
        function previewImage2(file)
        {
          var MAXWIDTH  = 260; 
          var MAXHEIGHT = 180;
          var div = document.getElementById('preview2');
          if (file.files && file.files[0])
          {
              div.innerHTML ='<img id=imghead2>';
              var img = document.getElementById('imghead2');
              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();
            file.blur();
            var src = document.selection.createRange().text;
            div.innerHTML = '<img id=imghead2>';
            var img = document.getElementById('imghead2');
            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;
        }
        function getPhotoSize2(obj){
        var fileSize = 0;
        var isIE = /msie/i.test(navigator.userAgent) && !window.opera;      
        if (isIE && !obj.files) {     
           fileSize = file.Size;     
        }else { 
           fileSize = obj.files[0].size;   
        } 
        fileSize=Math.round(fileSize/1024*100)/100; //单位为KB
        if(fileSize>=2048){
          alert("照片最大尺寸为2MB，请重新上传!");
        }else{
          previewImage2(obj);
        }
      }
</script>  
<script type="text/javascript">
      //图片上传预览    IE是用了滤镜。
        function previewImage3(file)
        {
          var MAXWIDTH  = 260; 
          var MAXHEIGHT = 180;
          var div = document.getElementById('preview3');
          if (file.files && file.files[0])
          {
              div.innerHTML ='<img id=imghead3>';
              var img = document.getElementById('imghead3');
              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();
            file.blur();
            var src = document.selection.createRange().text;
            div.innerHTML = '<img id=imghead3>';
            var img = document.getElementById('imghead3');
            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;
            function getPhotoSize3(obj){
        var fileSize = 0;
        var isIE = /msie/i.test(navigator.userAgent) && !window.opera;      
        if (isIE && !obj.files) {     
           fileSize = file.Size;     
        }else { 
           fileSize = obj.files[0].size;   
        } 
        fileSize=Math.round(fileSize/1024*100)/100; //单位为KB
        if(fileSize>=2048){
          alert("照片最大尺寸为2MB，请重新上传!");
        }else{
          previewImage3(obj);
        }
      }
        }
</script>   
</head>     
<body>
<div id="preview1">
    <img id="imghead1" width=100% height=auto border=0 src=''>
</div>
<input type="file" onchange="getPhotoSize1(this)" />   
<div id="preview2">
    <img id="imghead2" width=100% height=auto border=0 src=''>
</div>
<input type="file" onchange="getPhotoSize2(this)" />   
<div id="preview3">
    <img id="imghead3" width=100% height=auto border=0 src=''>
</div>
<input type="file" onchange="getPhotoSize3(this)" />     
</body>     
</html>