兼容好的JS图片上传预览代码

转 ： http://www.codefans.net/articles/1395.shtml

兼容好的JS图片上传预览代码（谷歌，IE11）

<html xmlns="http://www.w3.org/1999/xhtml">
 
<head>
<title>本地图片预览</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;
            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;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/btn_area.jpg'><!--无预览时的默认图像，自己弄一个-->
</div>
    <br/>
    <input type="file" onchange="previewImage(this)" />
</body>
</html>

#####################################

IE8, IE9,IE10 本地上传图片预览
<script>
function PreviewImage(imgFile)
{
    var filextension=imgFile.value.substring(imgFile.value.lastIndexOf("."),imgFile.value.length);
    filextension=filextension.toLowerCase();
    if ((filextension!='.jpg')&&(filextension!='.gif')&&(filextension!='.jpeg')&&(filextension!='.png')&&(filextension!='.bmp'))
    {
        alert("对不起，系统仅支持标准格式的照片，请您调整格式后重新上传，谢谢 !");
        imgFile.focus();
    }
    else
    {
        var path;
        if(document.all)//IE
        {
            imgFile.select();
            path = document.selection.createRange().text;
            document.getElementById("imgPreview").innerHTML="";
            document.getElementById("imgPreview").style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled='true',sizingMethod='scale',src=\"" + path + "\")";//使用滤镜效果
        }
        else//FF
        {
            path = imgFile.files[0].getAsDataURL();
            document.getElementById("imgPreview").innerHTML = "<img id='img1' width='120px' height='100px' src='"+path+"'/>";
            //document.getElementById("img1").src = path;
        }
    }
}
</script>
</head>
<body>
<input type="file" onchange='PreviewImage(this)' />
<br />
<div id="imgPreview" style='width:120px; height:100px;'>
    <img id="img1" src="" width="120" height="100" />
</div>