js上传和预览图片

时间：2023-11-09 19:25:26
[1].[代码] [HTML]代码 跳至 [1]

<!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">

#preview{width:260px;height:190px;border:1px solid #000;overflow:hidden;}

#imghead {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 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;

        }

</script>

</head>

<body>

<div id="preview">

    <img id="imghead" width=100 height=100 border=0 src='<%=request.getContextPath()%>/images/defaul.jpg'>

</div>

    <input type="file" onchange="previewImage(this)" />

</body>

</html>

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