鹰眼的实现
（ 1 ）载入地图到鹰眼控件
当地图载入到主 Map 控件时，同时也载入到鹰眼控件，在
axMapControl1_OnMapReplaced 事件响应函数（此函数上一讲中已经添加了）中添加如下代码：
private void axMapControl1_OnMapReplaced(object sender, IMapControlEvents2_OnMapReplacedEvent e)
{
// 前面代码省略
// 当主地图显示控件的地图更换时，鹰眼中的地图也跟随更换 this.axMapControl2.Map = new MapClass(); // 添加主地图控件中的所有图层到鹰眼控件中
for (int i = 1; i <= this.axMapControl1.LayerCount; i++) {
this.axMapControl2.AddLayer(this.axMapControl1.get_Layer(this.axMapControl1.LayerCount - i));
}
// 设置 MapControl 显示范围至数据的全局范围
this.axMapControl2.Extent = this.axMapControl1.FullExtent; // 刷新鹰眼控件地图
this.axMapControl2.Refresh(); }
（ 2 ）绘制鹰眼矩形框
为鹰眼控件 MapControl1 添加 OnExtentUpdated 事件，此事件是在主 Map 控件的显示范围改变时响应，从而相应更新鹰眼控件中的矩形框。其响应函数代码如下：
private void axMapControl1_OnExtentUpdated(object sender, IMapControlEvents2_OnExtentUpdatedEvent e)
{
// 得到新范围
IEnvelope pEnv = (IEnvelope)e.newEnvelope;
IGraphicsContainer pGra = axMapControl2.Map as IGraphicsContainer; IActiveView pAv = pGra as IActiveView;
// 在绘制前，清除 axMapControl2 中的任何图形元素 pGra.DeleteAllElements();
IRectangleElement pRectangleEle = new RectangleElementClass(); IElement pEle = pRectangleEle as IElement; pEle.Geometry = pEnv; // 设置鹰眼图中的红线框
IRgbColor pColor = new RgbColorClass(); pColor.Red = 255; pColor.Green = 0; pColor.Blue = 0;
pColor.Transparency = 255;
// 产生一个线符号对象
ILineSymbol pOutline = new SimpleLineSymbolClass(); pOutline.Width = 2; pOutline.Color = pColor; // 设置颜色属性
pColor = new RgbColorClass(); pColor.Red = 255; pColor.Green = 0; pColor.Blue = 0;
pColor.Transparency = 0; // 设置填充符号的属性
IFillSymbol pFillSymbol = new SimpleFillSymbolClass(); pFillSymbol.Color = pColor; pFillSymbol.Outline = pOutline;
IFillShapeElement pFillShapeEle = pEle as IFillShapeElement; pFillShapeEle.Symbol = pFillSymbol;
pGra.AddElement((IElement)pFillShapeEle, 0); // 刷新
pAv.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null); }
（ 3 ）鹰眼与主 Map 控件互动
为鹰眼控件 MapControl2 添加 OnMouseDown 事件，代码如下： private void axMapControl2_OnMouseDown(object sender, IMapControlEvents2_OnMouseDownEvent e)
{
if (this.axMapControl2.Map.LayerCount != 0) {
// 按下鼠标左键移动矩形框 if (e.button == 1) {
IPoint pPoint = new PointClass(); pPoint.PutCoords(e.mapX, e.mapY);
IEnvelope pEnvelope = this.axMapControl1.Extent; pEnvelope.CenterAt(pPoint);
this.axMapControl1.Extent = pEnvelope;
this.axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
}
// 按下鼠标右键绘制矩形框 else if (e.button == 2) {
IEnvelope pEnvelop = this.axMapControl2.TrackRectangle(); this.axMapControl1.Extent = pEnvelop;
this.axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
} } }
为鹰眼控件 MapControl2 添加 OnMouseMove 事件，主要实现按下鼠标左键的时候移动矩形框，同时也改变主的图控件的显示范围。代码如下：
private void axMapControl2_OnMouseMove(object sender, IMapControlEvents2_OnMouseMoveEvent e)
{
// 如果不是左键按下就直接返回 if (e.button != 1) return;
IPoint pPoint = new PointClass(); pPoint.PutCoords(e.mapX, e.mapY); this.axMapControl1.CenterAt(pPoint);
this.axMapControl1.ActiveView.PartialRefresh(esriViewDrawPhase.esriViewGeography, null, null);
}
鹰眼的实现
