图片上传点击浏览可以预览图片
图片上传点击浏览可以预览图片
leona_lily 发表于3年前
图片上传点击浏览可以预览图片
  • 发表于 3年前
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<!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 content="text/html; charset=utf-8" http-equiv="Content-Type">
<title>Js实现图片上传前在本地预览</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.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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