距离查询
距离查询，是指查询距离指定几何对象一定距离范围内的地物。对于点几何对象，则查询以该点为圆心，以距离半径画圆，落在该圆形范围内的地物；对于线和面几何对象，则查询距离对像边界一定范围内的地物。
本例将以World地图为例，[email protected]图层中，距离中心点30地图单位（度）内的首都，并把查询结果作为Marker标注在地图上。
var local, map, layer, markerLayer1, markerLayer2,
centerPoint = new SuperMap.Geometry.Point(121, 31),//指定的查询中心点
url = "http://www.supermapol.com/iserver/services/vm3sbiax/rest/maps/World";
var value = "VZ88xbrMEMpGv4yiisTojgVq",
name = "ak";
SuperMap.Credential.CREDENTIAL = new SuperMap.Credential(value, "ak");
function init(){
map = new SuperMap.Map("map",{controls: [
new SuperMap.Control.LayerSwitcher(),
new SuperMap.Control.ScaleLine(),
new SuperMap.Control.Zoom(),
new SuperMap.Control.Navigation({
dragPanOptions: {
enableKinetic: true
}
})]
});
layer = new SuperMap.Layer.TiledDynamicRESTLayer("World", url, {transparent: true, cacheEnabled: true}, {maxResolution:"auto"});
layer.events.on({"layerInitialized":addLayer});
markerLayer1 = new SuperMap.Layer.Markers("Markers");
markerLayer2 = new SuperMap.Layer.Markers("Markers");
//在地图上具体位置上画一个图形
var point = centerPoint,
size = new SuperMap.Size(44, 40), //查询点的图标的大小
offset = new SuperMap.Pixel(-(size.w/2), -size.h),
icon = new SuperMap.Icon("http://www.supermapol.com/static/portal/images/markers/mark_purple.png", size, offset);
markerLayer1.addMarker(new SuperMap.Marker(new SuperMap.LonLat(point.x, point.y), icon)); //把查询点作为Marker添加到地图上，并指定图标
}
function addLayer() {
map.addLayers([layer, markerLayer1, markerLayer2]);
map.setCenter(new SuperMap.LonLat(0, 0), 0);
}
function queryByDistance() {
markerLayer2.clearMarkers();
//查询[email protected]图层中，距离中心点30地图单位（度）内的首都
var queryByDistanceParams = new SuperMap.REST.QueryByDistanceParameters({
queryParams: new Array(new SuperMap.REST.FilterParameter({name: "[email protected]"})),
returnContent: true,
distance: 30,
geometry: centerPoint
});
//使用QueryByDistanceService接口，执行距离查询
var queryByDistanceService = new SuperMap.REST.QueryByDistanceService(url);
queryByDistanceService.events.on({
"processCompleted": processCompleted,
"processFailed": processFailed
});
queryByDistanceService.processAsync(queryByDistanceParams);
}
//返回查询结果，并把查询结果中的要素，作为Marker添加到地图上
function processCompleted(queryEventArgs) {
var i, j, result = queryEventArgs.result;
for(i = 0;i < result.recordsets.length; i++) {
for(j = 0; j < result.recordsets[i].features.length; j++) {
var point = result.recordsets[i].features[j].geometry,
size = new SuperMap.Size(44, 33),
offset = new SuperMap.Pixel(-(size.w/2), -size.h),
icon = new SuperMap.Icon("http://www.supermapol.com/static/portal/images/markers/mark_blue.png", size, offset);
markerLayer2.addMarker(new SuperMap.Marker(new SuperMap.LonLat(point.x, point.y), icon));
}
}
}
function processFailed(e) {
alert(e.error.errorMsg);
}
function clearFeatures() {
//清除上次的显示结果
markerLayer2.clearMarkers();
}
在线演示与源码编辑
您可以在线访问完整代码、体验演示效果，也可以直接在线编辑源码并实时查看效果。