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>

===================================

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兼容好的JS图片上传预览代码