js实现图片上传及预览---------------------->>兼容ie6-8 火狐以及谷歌

时间：2021-12-08 03:50:24
<head runat="server">

    <title>图片上传及预览(兼容ie6/7/8 firefox/chrome)</title>

    <script src="../Scripts/jquery-1.4.2.min.js" type="text/javascript"></script>

</head>

<body>

    <form id="form1" runat="server">

    <div>

        <div>

            <asp:FileUpload ID="fileAppImg" runat="server" Style="font-size: 13px;" onchange="previewImage(this,'preview','appImg')" /></div>

        <div id="preview" style="margin-top: 10px;">

            <img id="appImg" src="../SourceImg/ContentPage/AccountAuth/zjyl.jpg" alt="" style="margin-left: 1px;

                height: 214px; width: 160px;" />

        </div>

    </div>

    </form>

</body>

</html>

<%--图片上传预览--%>

<script type="text/javascript">

    //图片上传预览

    function previewImage(file, div, img) {

        MAXWIDTH = 160;

        MAXHEIGHT = 214;

        var div = document.getElementById(div);

        if (file.files && file.files[0]) {

            //验证图片大小

            var imgType = /\.[^\.]+$/.exec(file.value);

            if (imgType != ".jpg" && imgType != ".png") {

                alert("仅支持jpg和png两种格式的图片");

                file.value = "";

                $("#txtShowIcon").val("未选中文件");

                return;

            }

            div.innerHTML = "<img id='" + img + "'>";

            var img = document.getElementById(img);

            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 {

            //验证图片大小

            var imgType = /\.[^\.]+$/.exec(file.value);

            if (imgType != ".jpg" && imgType != ".png") {

                alert("仅支持jpg和png两种格式的图片");

                return;

            }

            var filePath = file.value;

            //IE浏览器

            var sFilter = 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';

            file.select();

            var src = document.selection.createRange().text;

            div.innerHTML = '<img id="' + img + '">';

            var img = document.getElementById(img);

            //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 };

        param.width = maxWidth;

        param.height = maxHeight;

        param.left = 0;

        param.top = 0;

        return param;

    }

</script>

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