鼠标拖动添加指北针，鼠标拖动的范围为指北针的范围

来源：互联网发布：他改变了中国知乎编辑：程序博客网时间：2024/06/05 17:14

         }

         //如果捕捉的区域对象为空或是区域高或宽为0 就退出函数
         if (m_Feedback == null)
         {
            m_Feedback = null;
            m_InUse = false;
            return;
         }
         IEnvelope envelope = m_Feedback.Stop();
         if ((envelope.IsEmpty) || (envelope.Width == 0) || (envelope.Height == 0))
         {
            m_Feedback = null;
            m_InUse = false;
            return;
         }
         //建立并弹出指北针样式选择框
         SelectSymbolDialog symbolForm = new SelectSymbolDialog("请选择指北针的显示样式：");
         //得到选中的指北针样式
         IStyleGalleryItem styleGalleryItem = symbolForm.GetItem(esriSymbologyStyleClass.esriStyleClassNorthArrows);
         // 释放选择窗体
         symbolForm.Dispose();
         //如果没有选择就退出函数
         if (styleGalleryItem == null)
         {
            return;
         }
         //得到焦点地图的框架结构
         IMapFrame mapFrame = (IMapFrame)m_HookHelper.ActiveView.GraphicsContainer.FindFrame(m_HookHelper.ActiveView.FocusMap);
         //创建一个环境框架
         IMapSurroundFrame mapSurroundFrame = new MapSurroundFrameClass();
         //把声明的环境框架和地图框架联系起来
         mapSurroundFrame.MapFrame = mapFrame;
         mapSurroundFrame.MapSurround = (IMapSurround)styleGalleryItem.Item;
         //把环境框架转换成一个元素
         IElement element = (IElement)mapSurroundFrame;
         element.Geometry = envelope;
         //把元素添加到容器中，并绘制
         m_HookHelper.ActiveView.GraphicsContainer.AddElement((IElement)mapSurroundFrame, 0);
         //刷新
         m_HookHelper.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, mapSurroundFrame, null);
         m_Feedback = null;
         m_InUse = false;
      }

}