1.首先添加放大和缩小的按钮

        <input type="image" disabled="disabled" id="btnZoomIn" style="height: 30px; width: 30px;"
            src="http://icons.iconarchive.com/icons/visualpharm/must-have/256/Zoom-In-icon.png" />
        <input type="image" disabled="disabled" id="btnZoomOut" style="height: 30px; width: 30px"
            src="http://icons.iconarchive.com/icons/visualpharm/must-have/256/Zoom-Out-icon.png" />

2.在reportLoaded中初始化

            var viewer = GrapeCity.ActiveReports.Viewer({
                element: '#viewerContainer',
                reportService: {
                    url: '/ActiveReports.ReportService.asmx'
                },
                uiType: 'desktop',
                reportLoaded: function () {
                    reportsButtons.prop('disabled', false);
                    currZoom = 1;
                    repName = viewer.option('report').id;
                    $("#btnZoomIn").prop("disabled", false);
                    $("#btnZoomOut").prop("disabled", false);
                },
                localeUri: 'Scripts/i18n/Localeuri.txt'
            });

3.添加放大缩小功能的实现

            $("#btnZoomIn").click(function () {
                var repExt = repName.substr(repName.indexOf(".") + 1)
                if (repExt == "rdlx") {
                    elem = $(".document-view");
                } else {
                    elem = $(".document-view").find("div").eq(0).children("div");
                }
                currZoom *= 1.1;
                elem.css("zoom", currZoom);
                elem.css("-moz-transform", "Scale(" + currZoom + ")");
                elem.css("-moz-transform-origin", "0 0");
           
            });
            $("#btnZoomOut").click(function () {
                var repExt = repName.substr(repName.indexOf(".") + 1)
                if (repExt == "rdlx") {
                    elem = $(".document-view");
                } else {
                    elem = $(".document-view").find("div").eq(0).children("div");
                }
                if (currZoom > 0.6) {
                    currZoom *= 0.9;
                    elem.css("zoom", currZoom);
                    elem.css("-moz-transform", "Scale(" + currZoom + ")");
                    elem.css("-moz-transform-origin", "0 0");
                 }
            });