onMouseClicked: {

            clickNum++

            if(clickNum == 1){//鼠标点击第一次 确实起点位置 并添加图形

                console.log(clickNum)

                dis_startPoint = mouse.mapPoint

                //graphicsOverlayer.graphics.append(createGraphic(dis_startPoint,startMarkSymbol))

                var dis_start = GeometryEngine.project(dis_startPoint,spatialReference.createWgs84())

                dis_startGraphic.geometry = dis_start

                console.log(dis_startPoint)

            }

            if(clickNum == 2){//鼠标点击第二次 确定终点位置 并添加图形

                console.log(clickNum)

                clickNum = 0;

                dis_endPoint = mouse.mapPoint

                var dis_end = GeometryEngine.project(dis_endPoint,spatialReference.createWgs84())

                dis_endGraphic.geometry = dis_end

                console.log(dis_endPoint)

                //创建路径线

                var polylineBuilder = ArcGISRuntimeEnvironment.createObject("PolylineBuilder", {spatialReference:SpatialReference.createWgs84()});

                polylineBuilder.addPoints([dis_startGraphic.geometry,dis_endGraphic.geometry])

                var polyline = polylineBuilder.geometry;

                //生成路径线

                var maxSegmentLength = 1;

                var unitOfMeasurement = ArcGISRuntimeEnvironment.createObject("LinearUnit", {linearUnitId: Enums.LinearUnitIdKilometers});

                var curveType = Enums.GeodeticCurveTypeGeodesic;

                var pathGeometry = GeometryEngine.densifyGeodetic(polyline, maxSegmentLength, unitOfMeasurement, curveType);

                pathGraphic.geometry = pathGeometry;

                //计算距离

                distanceText = GeometryEngine.lengthGeodetic(pathGeometry,unitOfMeasurement,curveType).toFixed(2)

                console.log("polyline builded",distanceText + "km")

            }

        }