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js上传图片，并预览

2014-03-20 09:29 120 查看

<!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>

引用地址：http://www.oschina.net/code/snippet_819257_22844

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标签： js 图片预览

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