在Arcengine的教程中，几乎都有创建鹰眼的教程，但是全是千篇一律，而且还有不足之处，比如在添加或者删除图层时，主MapCtrol的视图会发生变化，但鹰眼却不会触发事件，所以本文在原教程的基础上添加了图层添加和删除的监听事件。

1、首先是mapcontrol1的视图范围发生变化时 触发的事件

private void axMapControl1_OnExtentUpdated(object sender, IMapControlEvents2_OnExtentUpdatedEvent e)//当主视图的显示范围发生变化时，引发的事件 鹰眼
        {
            IGraphicsContainer pGraphicsContainer = axMapControl2.Map as IGraphicsContainer;
          
            pGraphicsContainer.DeleteAllElements();
            IRectangleElement pRectangle = new RectangleElementClass();
            IElement pEle = pRectangle as IElement;
            IEnvelope pEnv = e.newEnvelope as IEnvelope;
            pEle.Geometry = pEnv;
            //设置颜色
            IRgbColor rgb = new RgbColorClass();
            rgb.Red = 200;
            rgb.Green = 0;
            rgb.Blue = 0;
            rgb.Transparency = 255;

            //产生一个线符号
            ILineSymbol pLineSymbol = new SimpleLineSymbolClass();
            pLineSymbol.Width = 2;
            pLineSymbol.Color = rgb;
            //设置填充符号的属性
            IFillSymbol pFillSymbol = new SimpleFillSymbolClass();
            rgb.Transparency=0;
            pFillSymbol.Color = rgb;
            pFillSymbol.Outline = pLineSymbol;

            IFillShapeElement pfillshape = pRectangle as IFillShapeElement;
            pfillshape.Symbol = pFillSymbol;

            pGraphicsContainer.AddElement(pEle, 0);
            axMapControl2.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null);
            axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null);
        }

2、在加载mxd时触发的事件，但在添加图层时不会触发

  private void axMapControl1_OnMapReplaced_1(object sender, IMapControlEvents2_OnMapReplacedEvent e)
        {
            //鹰眼
            IMap pMap = axMapControl1.Map;
            for (int i = 0; i < pMap.LayerCount; i++)
            {
                axMapControl2.Map.AddLayer(pMap.get_Layer(i));
            }
            axMapControl2.Extent = axMapControl2.FullExtent;

        }

3、mapcontrol2的move与down事件

  private void axMapControl2_OnMouseDown(object sender, IMapControlEvents2_OnMouseDownEvent e)//点击鹰眼所引发的事件
        {
            if (e.button == 1)
            {
                IPoint pt = new PointClass();
                pt.X = e.mapX;
                pt.Y = e.mapY;
                //IEnvelope pEnvelope = axMapControl1.Extent as IEnvelope;
                //pEnvelope.CenterAt(pt);
                //axMapControl1.Extent = pEnvelope;
                axMapControl1.CenterAt(pt);
                axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);

            }
            if (e.button == 2)
            {
                IEnvelope pEnvelope = axMapControl2.TrackRectangle();
                axMapControl1.Extent = pEnvelope;
                axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
            }
        }

 private void axMapControl2_OnMouseMove(object sender, IMapControlEvents2_OnMouseMoveEvent e)//在鹰眼上移动引发的事件
        {
           
            if (e.button == 1)
            {
                IPoint pt = new PointClass();
                pt.X = e.mapX;
                pt.Y = e.mapY;
                axMapControl1.CenterAt(pt);
                axMapControl2.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null);
            }
        }

4、最后就是监听图层的添加与删除事件

  private IActiveViewEvents_Event itemEvent;//声明增删图层的事件

在Form_Load中添加以下代码：

            itemEvent = (IActiveViewEvents_Event)axMapControl1.Map;
            itemEvent.ItemAdded += new IActiveViewEvents_ItemAddedEventHandler(iae_ItemAdded);
            itemEvent.ItemDeleted += new IActiveViewEvents_ItemDeletedEventHandler(iae_ItemDeleted);

最后定义添加删除图层的方法：

 private void iae_ItemAdded(object m) //添加图层 触发的事件
        {
          
            for (int i = 0; i < axMapControl1.Map.LayerCount; i++)
            {

                axMapControl2.AddLayer(axMapControl1.get_Layer(i));
            }
            axMapControl2.Extent = axMapControl1.Extent;
            axMapControl2.Refresh();
        }

        private void iae_ItemDeleted(object c) // //删除图层 触发的事件
        {
            axMapControl2.Map.DeleteLayer(m_Layer);    // m_Layer 是根据HitTest方法得到的
            axMapControl2.Extent = axMapControl1.Extent;
             axMapControl2.Refresh();
        }

如此，在增删图层时，鹰眼也会随之变化

鹰眼的创建，弥补教材中鹰眼的不足之处