arcgis jsapi接口入门系列(5):几何(点线面)基本操作

        point: function () {
            //通过wkt生成点
            //wkt,代表点的坐标
            let wkt = "POINT(113.566806 22.22445)";

            //wkt转点几何对象
            // * @param apiInstance api
            //     * @param wkt wkt
            //     * @param sr 空间参考
            let point = mapUtil.geometry.wktToPoint(this.apiInstance, wkt, this.mapView.spatialReference);

            //通过坐标生成点,坐标格式是arcgis jsapi的标准,详情可看官方文档
            let coord = [113.566806, 22.22445];
            // * @param apiInstance api
            //     * @param wkt wkt
            //     * @param sr 空间参考
            point = mapUtil.geometry.coordToPoint(this.apiInstance, coord, this.mapView.spatialReference);

            //点转wkt
            wkt = mapUtil.geometry.pointToWkt(point);

            //获取点坐标
            let x = point.x;
            let y = point.y;


        },

线

        polyline: function () {
            //通过wkt生成线
            //wkt,代表线的坐标
            let wkt = "LINESTRING(113.545949 22.24015749,113.56989 22.24916,113.55324 22.220588)";
            // * @param apiInstance api
            //     * @param wkt wkt
            //     * @param sr 空间参考
            let polyline = mapUtil.geometry.wktToPolyline(this.apiInstance, wkt, this.mapView.spatialReference);

            //通过坐标生成线,坐标格式是arcgis jsapi的标准,详情可看官方文档
            let coord = [[[113.545949, 22.24015749], [113.56989, 22.24916], [113.55324, 22.220588]]];
            // * @param apiInstance api
            //     * @param coord 坐标对象,格式如:[[[113.545949, 22.24015749], [113.56989, 22.24916], [113.55324, 22.220588]]]
            //     * @param sr 空间参考
            polyline = mapUtil.geometry.coordToPolyline(this.apiInstance, coord, this.mapView.spatialReference);

            //线转wkt
            wkt = mapUtil.geometry.polylineToWkt(polyline);

            //几何对象是否几何正确的检查与修复
            //线和面(点不会)存在几何错误的情况,当有几何错误,几何对象的某些操作会出错,jsapi提供检查是否有几何错误的isSimple方法以及解决几何错误的simplify方法
            if (this.apiInstance.geometryEngine.isSimple(polyline) === false) {
                polyline = this.apiInstance.geometryEngine.simplify(polyline);
            }

            //遍历线的所有点的坐标
            //paths指线的“路径”,一条线可以有多条路径,但我们使用大多数情况都只有一条路径
            let path = polyline.paths[0];
            //遍历一条路径的所有点坐标
            for (let i = 0; i < path.length; i++) {
                //获取点坐标
                let pointCoord = path[i];
                let x = pointCoord[0];
                let y = pointCoord[1];

                //获取点对象
                let pointLine = polyline.getPoint(0, i);
            }

            //获取线的起点和终点(假设只有一个path)
            let pointStart = polyline.getPoint(0, 0);
            let pointEnd = polyline.getPoint(0, polyline.paths[0].length - 1);

            //获取线长度
            //jsapi提供两个获取长度的方法,大意是如果几何对象的坐标系是地理坐标系,例如wgs84,那就用geodesicLength,如果是平面坐标系,就用planarLength
            //参数2是计算的长度的单位,可以有这些值:meters | feet | kilometers | miles | nautical-miles | yards
            let length1 = this.apiInstance.geometryEngine.geodesicLength(polyline, "meters");
            //PS:因为测试数据是wgs84,所以把planarLength屏蔽了,其实不是无效代码
            // let length2 = this.apiInstance.geometryEngine.planarLength(polyline, "meters");

            //几何对象的范围
            let extent = polyline.extent;

        },

        polygon: function () {
            //通过wkt生成面
            let wkt = "POLYGON((113.527839 22.27028,113.527238 22.2557786,113.5437178 22.2597268,113.54423 22.2730306,113.527839 22.27028))";
            // * @param apiInstance api
            //     * @param wkt wkt
            //     * @param sr 空间参考
            let polygon = mapUtil.geometry.wktToPolygon(this.apiInstance, wkt, this.mapView.spatialReference);

            //通过坐标生成面,坐标格式是arcgis jsapi的标准,详情可看官方文档
            let coord = [[[113.527839, 22.27028], [113.527238, 22.2557786], [113.5437178, 22.2597268], [113.54423, 22.2730306], [113.527839, 22.27028]]];
            // * @param apiInstance api
            //     * @param coord 坐标对象 格式是arcgis jsapi标准,例如:[[[113.527839, 22.27028], [113.527238, 22.2557786], [113.5437178, 22.2597268], [113.54423, 22.2730306], [113.527839, 22.27028]]]
            //     * @param sr 空间参考
            polygon = mapUtil.geometry.coordToPolygon(this.apiInstance, coord, this.mapView.spatialReference);

            //面转wkt
            wkt = mapUtil.geometry.polygonToWkt(polygon);

            //几何对象是否几何正确的检查与修复
            //线和面(点不会)存在几何错误的情况,当有几何错误,几何对象的某些操作会出错,jsapi提供检查是否有几何错误的isSimple方法以及解决几何错误的simplify方法
            if (this.apiInstance.geometryEngine.isSimple(polygon) === false) {
                polygon = this.apiInstance.geometryEngine.simplify(polygon);
            }

            //遍历面的所有点的坐标
            //rings指面的“路径”,一条面对象可以有多个面,但我们使用大多数情况都只有一个面
            let ring = polygon.rings[0];
            //遍历一个面的所有点坐标
            for (let i = 0; i < ring.length; i++) {
                //获取点坐标
                let pointCoord = ring[i];
                let x = pointCoord[0];
                let y = pointCoord[1];

                //获取点对象
                let pointLine = polygon.getPoint(0, i);
            }

            //获取面的周长
            //jsapi提供两个获取长度的方法,大意是如果几何对象的坐标系是地理坐标系,例如wgs84,那就用geodesicLength,如果是平面坐标系,就用planarLength
            //参数2是计算的长度的单位,可以有这些值:meters | feet | kilometers | miles | nautical-miles | yards
            let length1 = this.apiInstance.geometryEngine.geodesicLength(polygon, "meters");
            //PS:因为测试数据是wgs84,所以把planarLength屏蔽了,其实不是无效代码
            // let length2 = this.apiInstance.geometryEngine.planarLength(polygon, "meters");

            //获取面积也是两个方法,也是geodesicArea和planarArea,情况和获取长度的相同
            //参数2是计算的面积的单位,可以有这些值:acres | ares | hectares | square-feet | square-meters | square-yards | square-kilometers | square-miles
            //PS:计算面积前要先检查是否有几何错误,目前已知有几何错误会导致面积计算不准确
            let area1 = this.apiInstance.geometryEngine.geodesicArea(polygon, "square-meters");
            // let area2 = this.apiInstance.geometryEngine.planarArea(polygon, "square-meters");

            //获取面是否自相交
            let isSelfIntersecting = polygon.isSelfIntersecting;

            //获取面的几何中心点
            let pointCenter = polygon.centroid;

            //几何对象的范围
            let extent = polygon.extent;

            //把extent转面
            //PS:extent是矩形,也属于面(多边形),因此逻辑上可以单向转换
            let polygon2 = this.apiInstance.Polygon.fromExtent(extent);
        },

extent(范围,矩形,envelope)

        extent: function () {
            //先生成任意矩形,作为测试数据
            let wkt = "LINESTRING(113.545949 22.24015749,113.56989 22.24916,113.55324 22.220588)";
            let polyline = mapUtil.geometry.wktToPolyline(this.apiInstance, wkt, this.mapView.spatialReference);
            let extent = polyline.extent;

            //矩形4个角的坐标
            let xmax = extent.xmax;
            let xmin = extent.xmin;
            let ymax = extent.ymax;
            let ymin = extent.ymin;
            //矩形的宽高
            let width = extent.width;
            let height = extent.height;

            //矩形中心点
            let centerPoint = extent.center;

            let point1 = mapUtil.geometry.xyToPoint(this.apiInstance, 113.545949, 22.24015749, this.mapView.spatialReference);
            //把矩形移动到以某个点为中心点的位置
            let extent3 = extent.centerAt(point1);

            //把矩形按比例缩放,例如值为1.2即放到到原来的1.2倍
            extent3 = extent.expand(1.2);

            //生成矩形
            let extent2 = new this.apiInstance.Extent({
                xmin: -9177882,
                ymin: 4246761,
                xmax: -9176720,
                ymax: 4247967,
                spatialReference: this.mapView.spatialReference
            });


        },

几何计算

        geometryCalculate: function () {
            //测试的线
            let wkt = "LINESTRING(113.545949 22.24015749,113.56989 22.24916,113.55324 22.220588)";
            let polyline = mapUtil.geometry.wktToPolyline(this.apiInstance, wkt, this.mapView.spatialReference);

            //测试的面
            wkt = "POLYGON((113.527839 22.27028,113.527238 22.2557786,113.5437178 22.2597268,113.54423 22.2730306,113.527839 22.27028))";
            let polygon = mapUtil.geometry.wktToPolygon(this.apiInstance, wkt, this.mapView.spatialReference);

            //以下只包含常用的几何操作,其他操作请看官方文档的geometryEngine类的方法

            //生成缓冲区
            //参数1:生成缓冲区的几何对象
            //参数2:缓冲半径
            //参数3:缓冲半径单位
            //PS:关于单位。当几何对象坐标系为地理坐标系时,如果单位用平面的坐标系,例如米,会报错,但是单位的选项没有经纬度
            //这情况可以传null,官方文档说法是默认值就是几何对象坐标系的单位
            let bufferPolygon = this.apiInstance.geometryEngine.buffer(polyline, 100, null);

            //判断两个几何对象是否重叠
            //intersects关系是只要有任意部分重叠就为true
            let isIntersect = this.apiInstance.geometryEngine.intersects(polyline, bufferPolygon);

            //获取两个几何对象的重叠部分并输出新的几何对象
            let intersectGeometry = this.apiInstance.geometryEngine.intersect(polygon, bufferPolygon);

            //计算两个几何对象的距离
            //参数3:距离的单位
            let distance = this.apiInstance.geometryEngine.distance(polyline, bufferPolygon, null);
        },
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