arcgis jsapi接口入门系列（10）：图形高亮

jsapi也有提供高亮的实现接口，但这里没用，而用的是一种改变图形（graphic）样式的思路

本文实现效果是：地图有多个面图形，当鼠标移动到面的上方，面高亮显示，鼠标移出后高亮解除

初始化

        //高亮初始化
        highlightInit: function () {
            //添加一个图形图层存放要高亮的图形
            let layer = new this.apiInstance.GraphicsLayer({
                id: "highlightLayer",
                //空间参考，一般要跟地图的一样
                spatialReference: this.mapView.spatialReference,
            });
            //图层添加到地图
            this.map.add(layer);

            //添加两个面
            let wkt = "POLYGON((113.527839 22.27028,113.527238 22.2557786,113.5437178 22.2597268,113.54423 22.2730306,113.527839 22.27028))";
            let style = {
                color: [50, 205, 50, 0.2],
                outline: {
                    color: [255, 0, 0],
                     1
                }
            };
            let graphic = mapUtil.geometry.wktToPolygonGraphic(this.apiInstance, wkt, style, this.mapView.spatialReference, null);
            layer.graphics.add(graphic);

            wkt = "POLYGON((113.51319 22.26819,113.51473 22.257561,113.520480 22.25747,113.519966 22.26904,113.51319 22.26819))";
            graphic = mapUtil.geometry.wktToPolygonGraphic(this.apiInstance, wkt, style, this.mapView.spatialReference, null);
            layer.graphics.add(graphic);
        },

监听鼠标移动事件，这段代码通常在地图初始化后执行

                    //鼠标移动事件
                    this.mapView.on("pointer-move", function (event) {
                        this.mapView.hitTest(event).then(function (response) {
                            //鼠标移动到图形时高亮图形的实现
                            //原理：监听鼠标移动事件，当鼠标移动到某图形时，就改变改图形的样式（高亮实际是换一种更“亮”的样式），然后鼠标移出图形，就把图形样式恢复回去

                            //当前鼠标下的图形，也就是应该高亮的图形
                            let pointerFacilityGraphic = null;

                            if (response.results[0]) {
                                //获取到当前鼠标下方的图形
                                var graphic = response.results[0].graphic;

                                if (graphic.layer) {
                                    if (graphic.layer.id === "highlightLayer") {
                                        //当前鼠标下的图形，也就是应该高亮的图形
                                        pointerFacilityGraphic = graphic;
                                    }
                                }
                            }

                            //实现高亮图形效果
                            if (pointerFacilityGraphic == null && this.highlightFacilityGraphic != null) {
                                //当鼠标下没有图形，当前有高亮图形，把当前高亮的效果去掉
                                this.setGraphicHighlight(this.highlightFacilityGraphic, false);
                                this.highlightFacilityGraphic = null;
                            }
                            else if (pointerFacilityGraphic != null && this.highlightFacilityGraphic == null) {
                                //当鼠标下有图形，当前没有高亮图形，把鼠标图形设为高亮
                                this.setGraphicHighlight(pointerFacilityGraphic, true);
                                this.highlightFacilityGraphic = pointerFacilityGraphic;
                            }
                            else if (pointerFacilityGraphic != null && this.highlightFacilityGraphic === pointerFacilityGraphic) {
                                //当鼠标下有图形，且跟当前高亮图形是同一个，不做任何事
                            }
                            else if (pointerFacilityGraphic != null && this.highlightFacilityGraphic !== pointerFacilityGraphic) {
                                //当鼠标下有图形，且跟当前高亮图形不同一个，把鼠标图形设为高亮，把当前高亮的效果去掉
                                this.setGraphicHighlight(this.highlightFacilityGraphic, false);
                                this.setGraphicHighlight(pointerFacilityGraphic, true);
                                this.highlightFacilityGraphic = pointerFacilityGraphic;
                            }

                        }.bind(this))
                    }.bind(this));

设置图层高亮

        //设置图形高亮效果
        //参数1：图形
        //参数2：是否高亮
        setGraphicHighlight: function (graphic, isHighlight) {
            //基础样式
            //本例中，正常样式的填充透明度是0.2，高亮时透明度0.7
            let style = {
                type: "simple-fill",
                color: [50, 205, 50, 0.2],
                outline: {
                    color: [255, 0, 0],
                     1
                }
            };

            if (isHighlight) {
                //高亮
                style.color = [50, 205, 50, 0.7];
                graphic.symbol = style;
            }
            else {
                //不高亮
                style.color = [50, 205, 50, 0.2];
                graphic.symbol = style;
            }
        },