转自原文

 

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<喎�"/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+PGltZyBzcmM9"/uploadfile/Collfiles/20141028/20141028091440197.png" alt="\">

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({            width:175,            height:75,            title:"请输入缓冲区距离",            content:""        });        $("#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

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。