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Firefox3,IE6,IE7,IE8上传图片预览(转)

 
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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 http-equiv="Content-Type" content="text/html; charset=utf-8" />       
<title>Firefox3,IE6,IE7,IE8上传图片预览</title>       
<style type="text/css">
#preview_wrapper{        
    display:inline-block;        
    width:300px;        
    height:300px;        
    background-color:#CCC;        
}        
#preview_fake{ /* 该对象用户在IE下显示预览图片 */        
    filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);        
}        
#preview_size_fake{ /* 该对象只用来在IE下获得图片的原始尺寸,无其它用途 */        
    filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);          
    visibility:hidden;        
}        
#preview{ /* 该对象用户在FF下显示预览图片 */        
    width:300px;        
    height:300px;        
}
</style>
<style type="text/css">       
#preview_wrapper{        
    display:inline-block;        
    width:300px;        
    height:300px;        
    background-color:#CCC;        
}        
#preview_fake{ /* 该对象用户在IE下显示预览图片 */        
    filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);        
}        
#preview_size_fake{ /* 该对象只用来在IE下获得图片的原始尺寸,无其它用途 */        
    filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);          
    visibility:hidden;        
}        
#preview{ /* 该对象用户在FF下显示预览图片 */        
    width:300px;        
    height:300px;        
} 
</style>   
<script type="text/javascript"> 
       
function onUploadImgChange(sender){        
    if( !sender.value.match( /.jpg|.gif|.png|.bmp/i ) ){        
        alert('图片格式无效!');        
        return false;        
    }        
            
    var objPreview = document.getElementById( 'preview' );        
    var objPreviewFake = document.getElementById( 'preview_fake' );        
    var objPreviewSizeFake = document.getElementById( 'preview_size_fake' );
    
            
    if( sender.files &&  sender.files[0] ){        
        objPreview.style.display = 'block';        
        objPreview.style.width = 'auto';        
        objPreview.style.height = 'auto';        
                
        // Firefox 因安全性问题已无法直接通过 input[file].value 获取完整的文件路径        
        objPreview.src = sender.files[0].getAsDataURL();            
    }else if( objPreviewFake.filters ){         
        // IE7,IE8 在设置本地图片地址为 img.src 时出现莫名其妙的后果        
        //(相同环境有时能显示,有时不显示),因此只能用滤镜来解决        
                
        // IE7, IE8因安全性问题已无法直接通过 input[file].value 获取完整的文件路径        
        sender.select();        
        var imgSrc = document.selection.createRange().text;        
                
        objPreviewFake.filters.item(        
            'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;        
        objPreviewSizeFake.filters.item(        
            'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;        
                
        autoSizePreview( objPreviewFake,         
            objPreviewSizeFake.offsetWidth, objPreviewSizeFake.offsetHeight );        
        objPreview.style.display = 'none';        
    }        
}        
       
function onPreviewLoad(sender){
    autoSizePreview( sender, sender.offsetWidth, sender.offsetHeight );        
}
       
function autoSizePreview( objPre, originalWidth, originalHeight ){     
    var zoomParam = clacImgZoomParam( 300, 300, originalWidth, originalHeight );        
    objPre.style.width = zoomParam.width + 'px';        
    objPre.style.height = zoomParam.height + 'px';        
    objPre.style.marginTop = zoomParam.top + 'px';        
    objPre.style.marginLeft = zoomParam.left + 'px';        
}        
       
function clacImgZoomParam( maxWidth, maxHeight, width, height ){        
    var param = { width:width, height:height, top:0, left:0 };        
            
    if( width>maxWidth || height>maxHeight ){        
        rateWidth = width / maxWidth;        
        rateHeight = height / maxHeight;        
                
        if( rateWidth > rateHeight ){        
            param.width =  maxWidth;        
            param.height = height / rateWidth;        
        }else{        
            param.width = width / rateHeight;        
            param.height = maxHeight;        
        }        
    }        
            
    param.left = (maxWidth - param.width) / 2;        
    param.top = (maxHeight - param.height) / 2;        
            
    return param;        
}        
</script>       
       
</head>       
       
<body>       
    <div id="preview_wrapper">       
        <div id="preview_fake">       
            <img id="preview" onload="onPreviewLoad(this)"/>       
        </div>       
    </div>       
    <br/>       
    <input id="upload_img" type="file" onchange="onUploadImgChange(this)"/>       
    <br/>       
    <img id="preview_size_fake"/><span id="swh"></span>     
</body>       
</html>

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