jquery实现图片上传前本地预览

时间：2023-11-25 12:34:08
<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script src="js/jquery1.8.3-min.js"></script>
</head>
<body>
<div style="width:500px;margin:0px auto;"><h2>图片上传预览演示</h2>
    <div><img id="ImgPr" width="120" height="120" /></div>
    <input type="file" id="up" />
</div>
<script>
    /*
     *参数说明: Img:图片ID;Width:预览宽度;Height:预览高度;ImgType:支持文件类型;Callback:选择文件显示图片后回调方法;
     *使用方法:
     <div>
     <img id="ImgPr" width="120" height="120" /></div>
     <input type="file" id="up" />
     把需要进行预览的IMG标签外 套一个DIV 然后给上传控件ID给予uploadPreview事件
     $("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120, ImgType: ["gif", "jpeg", "jpg", "bmp", "png"], Callback: function () { }});
     */
    jQuery.fn.extend({
        uploadPreview: function (opts) {
            var _self = this,
                    _this = $(this);
            opts = jQuery.extend({
                Img: "ImgPr",
                Width: 100,
                Height: 100,
                ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],
                Callback: function () {}
            }, opts || {});
            _self.getObjectURL = function (file) {
                var url = null;
                if (window.createObjectURL != undefined) {
                    url = window.createObjectURL(file)
                } else if (window.URL != undefined) {
                    url = window.URL.createObjectURL(file)
                } else if (window.webkitURL != undefined) {
                    url = window.webkitURL.createObjectURL(file)
                }
                return url
            };
            _this.change(function () {
                if (this.value) {
                    if (!RegExp("\.(" + opts.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {
                        alert("选择文件错误,图片类型必须是" + opts.ImgType.join("，") + "中的一种");
                        this.value = "";
                        return false
                    }
                    if ($.browser.msie) {
                        try {
                            $("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
                        } catch (e) {
                            var src = "";
                            var obj = $("#" + opts.Img);
                            var div = obj.parent("div")[0];
                            _self.select();
                            if (top != self) {
                                window.parent.document.body.focus()
                            } else {
                                _self.blur()
                            }
                            src = document.selection.createRange().text;
                            document.selection.empty();
                            obj.hide();
                            obj.parent("div").css({
                                'filter': 'progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)',
                                'width': opts.Width + 'px',
                                'height': opts.Height + 'px'
                            });
                            div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src
                        }
                    } else {
                        $("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
                    }
                    opts.Callback()
                }
            })
        }
    });

    $(function () {
        $("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120 });
    });
</script>
</body>
</html>

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