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js实现上传图片实时预览，兼容chrome IE firefox多浏览器

2016-01-27 16:53 1201 查看

直接上代码吧，一张图、多张图，都比较适用

<html>
<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">
.imgDiv{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,imgDiv,imgId){
//file表单，图片显示div，图片id
var MAXWIDTH  = 260;
var MAXHEIGHT = 180;
var div = document.getElementById(imgDiv);
if (file.files && file.files[0])
{
div.innerHTML ='<img class="imghead" id='+imgId+'>';
var img = document.getElementById(imgId);
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 class="imghead" id='+imgId+'>';
var img = document.getElementById(imgId);
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-left:"+rect.left+"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 class="imgDiv" id="d0"></div>
<input type="file" onchange="previewImage(this,'d0','img0')" />
<div class="imgDiv" id="d1"></div>
<input type="file" onchange="previewImage(this,'d1','img1')" />
<div class="imgDiv" id="d2"></div>
<input type="file" onchange="previewImage(this,'d2','img2')" />
<div class="imgDiv" id="d3"></div>
<input type="file" onchange="previewImage(this,'d3','img3')" />

</body>
</html>

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标签： javascript 上传图片浏览器兼容火狐 IE

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