空间查询的实现

空间查询是一个经常要用到的功能，它是通过给定一定的范围，查询得到在这个空间范围内的要素的查询方式。下面的代码是在返回鼠标点击点周围长宽100个地图单位的矩形范围内的要素。

过程描述

Dim pMap As IMap Dim pPoint As IPoint Set pMap = MapControl1.Map Dim pFeatureLayer As IFeatureLayer Set pFeatureLayer = pMap.Layer(1) Set pPoint = MapControl1.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(x, y) Dim pEnv As IEnvelope Set pEnv = New Envelope Set pEnv = MapControl1.ActiveView.Extent pEnv.Height = 100 pEnv.Width = 100 pEnv.CenterAt pPoint MsgBox pPoint.x MsgBox pEnv.XMax Dim pGeometry As IGeometry Set pGeometry = pEnv Set pGeometry.SpatialReference = pMap.SpatialReference pFeatureLayer.Selectable = True Dim pSFilter As ISpatialFilter Set pSFilter = New SpatialFilter With pSFilter Set .Geometry = pGeometry .GeometryField = pFeatureLayer.FeatureClass.ShapeFieldName .SpatialRel = esriSpatialRelIntersects End With Dim b As Boolean b = pSFilter.FilterOwnsGeometry Dim pFeatureCursor As IFeatureCursor Set pFeatureCursor = pFeatureLayer.Search(pSFilter, False)