地图的放大、缩小和漫游

    利用工具方式进行地图操作，包括两个事件，第一个事件是工具栏上按钮点击事件；第二个事件是MapObjects控件上的操作事件（MouseDown事件）。
    对第一个事件的响应通常是改变鼠标指针的形状，同时记录按钮的功能。
    

private void toolStrip1_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
        {
            switch (e.ClickedItem.Name)
            {
                case "Zoomin":
                    map_mouse_symbol = "zoomin";
                    axMap1.MousePointer = MapObjects2.MousePointerConstants.moZoomIn;
                    break;
                case "Zoomout":
                    map_mouse_symbol = "zoomout";
                    axMap1.MousePointer = MapObjects2.MousePointerConstants.moZoomOut;
                    break;
                case "Pan":
                    map_mouse_symbol = "pan";
                    axMap1.MousePointer = MapObjects2.MousePointerConstants.moPan;
                    break;
                case "FullView":
                    map_mouse_symbol = "fullview";
                    axMap1.MousePointer = MapObjects2.MousePointerConstants.moArrow;
                    axMap1.Extent = axMap1.FullExtent;
                    axMap1.Refresh();
                    break;
            }
        }

    对于第二个事件的响应是根据点击按钮的功能，从而执行相应的代码。如果是放大事件，则利用MapObjects控件的TrackRectangle返回用户在地图上定义的Rectangle，并返回放大后地图的范围；如果是缩小事件，则根据定义的Rectangle大小确定比例，即地图控件高度（或宽度）与用户定义的Rectangle高度（或宽度）之比，Rectangle越小，缩小的比例越大；如果是漫游功能，则利用MapObjects控件的Pan方法。
    

MapObjects2.Rectangle rect; //范围
switch (axMap1.MousePointer)
{
    //放大
    case MapObjects2.MousePointerConstants.moZoomIn:
    {
         rect = axMap1.TrackRectangle(); //得到鼠标拖动范围
         if (rect == null || rect.Width < 0.00005 || rect.Height < 0.00005) //如果选择区域很小，可以认为是 单击、点选
         {
             rect = axMap1.Extent;
             rect.ScaleRectangle(0.5); //设置放大比例
          }
          axMap1.Extent = rect;
          break;
     }

     //缩小 ，当点击图层缩小时，由于宽度和高度为0，将会发生分母为0错误，用户可自行解决
     case MapObjects2.MousePointerConstants.moZoomOut:
     {
         MapObjects2.Rectangle Tempr;
         Tempr = axMap1.Extent;
         rect = axMap1.TrackRectangle();
         double NewSR;
         if (rect == null || rect.Width < 0.00005 || rect.Height < 0.00005)
         {
             if (axMap1.Extent.Width / rect.Width > axMap1.Extent.Height / rect.Height)
             {
                NewSR = axMap1.Extent.Height / rect.Height;
             }
             else
             {
                 NewSR = axMap1.Extent.Width / rect.Width;
             }
             Tempr.ScaleRectangle(NewSR);
          }
          else
          {
             Tempr.ScaleRectangle(2.0); //设置缩小比率
          }
          axMap1.Extent = Tempr;
          break;
      }
      //漫游
      case MapObjects2.MousePointerConstants.moPan:
      {
           axMap1.Pan();
           break;
      }