Arcgis for Js实现graphiclayer的空间查询（续）

上文中，实现了简单的针对graphiclayer的空间查询工作，在本节，将更加详细的介绍针对graphiclayer的空间查询。首先，空间查询的方式：提供多种类型的空间查询，包括点周边、线周边、面内等多种方式；其次，图形绘制完成后状态的展示；再次，结果的显示。实现后的结果如下：

点周边——输入缓冲区距离

点周边——查询结果

线周边——输入缓冲区距离

线周边——查询结果

面内——矩形

面内——圆形

面内——多边形

首先，绘制图形。

            var drawToolbar = new esri.toolbars.Draw(map);
            drawToolbar.on("draw-end",showDrawResults);
            on(dom.byId("point"), "click", function(){
                restoreMap();
                drawToolbar.activate(esri.toolbars.Draw.POINT);
            });
            on(dom.byId("polyline"), "click", function(){
                restoreMap();
                drawToolbar.activate(esri.toolbars.Draw.POLYLINE);
            });
            on(dom.byId("extent"), "click", function(){
                restoreMap();
                drawToolbar.activate(esri.toolbars.Draw.EXTENT);
            });
            on(dom.byId("circle"), "click", function(){
                restoreMap();
                drawToolbar.activate(esri.toolbars.Draw.CIRCLE);
            });
            on(dom.byId("polygon"), "click", function(){
                restoreMap();
                drawToolbar.activate(esri.toolbars.Draw.POLYGON);
            });
            /**
             * 显示绘制结果
             */
            function showDrawResults(evt){
                drawToolbar.deactivate();
                map.setMapCursor("default");
                var geometry = evt.geometry;
                if(geometry.type==="point" || geometry.type==="polyline"){
                    $('#map').modalInfowindow({
                        175,
                        height:75,
                        title:"请输入缓冲区距离",
                        content:"<input type='text' id='distance' />"
                    });
                    $("#distance").focus();
                    $("#distance").keydown(function (e){
                        // 回车键事件
                        if(e.which == 13) {
                            $("#close").click();
                        }
                    });
                    on(dom.byId("close"), "click", function(){
                        distance = dom.byId("distance").value;
                        $("#modal").remove();
                        doBuffer(geometry);
                    });
                }
                else{
                    queryGraphicByPolygon(geometry);
                }
            };

当为点或者线的时候，得首先进行缓冲区分析，获取缓冲区的geometry，缓冲区分析的代码如下：

            /**
             * 执行buffer
             * @param geometry
             */
            function doBuffer(geometry) {
                var symbol = null;
                switch (geometry.type) {
                    case "point":
                        symbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.STYLE_CIRCLE,
                                7,
                                new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                                        new Color([0,0,255]),
                                        1
                                ),
                                new Color([0,0,255])
                        );
                        break;
                    case "polyline":
                        symbol = new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                                new Color([0,0,255]),
                                2
                        );
                        break;
                    case "polygon":
                        symbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_NONE,
                                new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
                                        new Color([0,0,255]),
                                        2
                                ),
                                new Color([0,0,255,0.25]));
                        break;
                }
                var graphic = new Graphic(geometry, symbol);
                map.graphics.add(graphic);

                //setup the buffer parameters
                var params = new BufferParameters();
                params.distances = [distance];
                params.bufferSpatialReference = map.spatialReference;
                params.outSpatialReference = map.spatialReference;
                params.unit = GeometryService["UNIT_KILOMETER"];

                if (geometry.type === "polygon") {
                    //if geometry is a polygon then simplify polygon.  This will make the user drawn polygon topologically correct.
                    gsvc.simplify([geometry], function(geometries) {
                        params.geometries = geometries;
                        gsvc.buffer(params, function(bfGeometry){
                            queryGraphicByPolygon(bfGeometry[0]);
                        });
                    });
                }
                else {
                    params.geometries = [geometry];
                    gsvc.buffer(params, function(bfGeometry){
                        queryGraphicByPolygon(bfGeometry[0]);
                    });
                }
            }

在执行缓冲区分析的时候，会用到geometryservice。代码如下：

var gsvc = new GeometryService("http://localhost:6080/arcgis/rest/services/Utilities/Geometry/GeometryServer");

当缓冲区分析完成或者面要素绘制完成以后的geometry都为polygon，此时，执行空间查询：

            /**
             * 根据多边形进行查询
             * @param geometry
             */
            function queryGraphicByPolygon(geometry){
                var graphics = chartLayer.graphics;

                var sfs = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID,
                        new SimpleLineSymbol(SimpleLineSymbol.STYLE_DASHDOT,
                                new Color([255,0,0]), 2),
                        new Color([255,255,0,0.25])
                );
                var graphic = new Graphic(geometry,sfs);
                map.graphics.add(graphic);

                for(var i= 0, total=graphics.length;i<total;i++){
                    if(geometry.contains(graphics[i].geometry)){
                        selectedGraphics.push(graphics[i]);
                        graphics[i].symbol = createSymbol(iconPath,"#0ff");
                        chartLayer.redraw();
                    }
                }
            }

空间查询的逻辑很简单，就是通过判断自定义的区域内是否包含各点。