ArcEngine开发——点击选择要素功能实现

实现了 地图  元素的点击选择如图）

        private void   axMapControl1_OnMouseDown(object sender, ESRI.ArcGIS.Controls.IMapControlEvents2_OnMouseDownEvent e)

          {

              int m_px = e.x;

              int m_py = e.y;

              IMap m_pMap = axMapControl1.Map;

           ClickSelectFeature(ref m_pMap,m_px,m_py);

          }

          private void ClickSelectFeature( ref IMap m_pMap, int x,int y)

        {        

              // get the layer

              IFeatureLayer pFeatureLayer = m_pMap.get_Layer(0) as IFeatureLayer;

              if (pFeatureLayer == null) return;

              IFeatureClass pFeatureClass = pFeatureLayer.FeatureClass;//get the feature

              if (pFeatureClass == null) return;

           //get mouse position

              IActiveView pActiveView = m_pMap as IActiveView;

              IPoint pPoint = pActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(x, y);

            //Use a 4 pixel buffer around the cursor for feature search
double length;

              length = ConvertPixelsToMapUnits(pActiveView, 4);

              ITopologicalOperator pTopo = pPoint as ITopologicalOperator;

              IGeometry pBuffer = pTopo.Buffer(length);//建立4个地图单位的缓冲区

              IGeometry pGeometry =  pBuffer.Envelope;//确定鼠标周围隐藏的选择框

              //新建一个空间约束器

              ISpatialFilter pSpatialFilter;

              IQueryFilter pFilter;

           //设置查询约束条件

           pSpatialFilter = new SpatialFilter();

              pSpatialFilter.Geometry = pGeometry;


              switch (pFeatureClass.ShapeType)

              {

               case esriGeometryType.esriGeometryPoint:

                      pSpatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelContains;

                      break;

               case esriGeometryType.esriGeometryPolyline:

                      pSpatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelCrosses;

                      break;

                  case esriGeometryType.esriGeometryPolygon:

                      pSpatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;

                      break;

                  default:

                      break;

              }

           pSpatialFilter.GeometryField = pFeatureClass.ShapeFieldName;

              pFilter = pSpatialFilter;

           //Do the Search 从图层中查询出满足约束条件的元素

              IFeatureCursor pCursor = pFeatureLayer.Search(pFilter, false);


              //select

              IFeature pFeature = pCursor.NextFeature();

              m_pMap.SelectFeature(pFeatureLayer, pFeature);          

              while (pFeature != null)

              {

                  m_pMap.SelectFeature(pFeatureLayer, pFeature);

                  pFeature = pCursor.NextFeature();

              }

           pActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeoSelection, null, null);

      }

       private double ConvertPixelsToMapUnits(IActiveView pActiveView, double pixelUnits)

          {

              // Uses the ratio of the size of the map in pixels to map units to do the conversion

              IPoint p1 = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.UpperLeft;

              IPoint p2 = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.UpperRight;

              int x1, x2, y1, y2;

              pActiveView.ScreenDisplay.DisplayTransformation.FromMapPoint(p1, out x1, out y1);

              pActiveView.ScreenDisplay.DisplayTransformation.FromMapPoint(p2, out x2, out y2);

              double pixelExtent = x2 - x1;

              double realWorldDisplayExtent = pActiveView.ScreenDisplay.DisplayTransformation.VisibleBounds.Width;

              double sizeOfOnePixel = realWorldDisplayExtent / pixelExtent;

              return pixelUnits * sizeOfOnePixel;

          }

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