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用戶端讀取圖檔檔案

<!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>Ajax檔案上傳</title>      

<style type="text/css"> 

#preview{width:100px;height:100px;border:1px solid #000;overflow:hidden;} 

#imghead {filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);} 

</style> 

<script type="text/javascript"> 

function previewImage(file) 

  var MAXWIDTH  = 100; 

  var MAXHEIGHT = 100; 

  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 

    var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="'; 

    file.select(); 

    var src = document.selection.createRange().text; 

    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;margin-left:"+rect.left+"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='../images/head01_big.jpg'> 

</div> 

    <br/>      

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

</body>      

</html>