首先，添加两个MapControl,主图命名为mapMain，鹰眼图命名为mapEye
Imports ESRI.ArcGIS.Geometry
Imports ESRI.ArcGIS.Display
Public Class Form1
Private EyeRect As IEnvelope '鹰眼矩形框范围
Private EyeSym As ISimpleFillSymbol ‘鹰眼矩形框符号
’得到鹰眼矩形框范围
Private Function GetEyeRect() As IEnvelope
Dim pEnvMainFull As IEnvelope
pEnvMainFull = mapMain.FullExtent
Dim pEnvMainExt As IEnvelope
pEnvMainExt = mapMain.Extent
Dim pEnvEyeFull As IEnvelope
pEnvEyeFull = mapEye.FullExtent
Dim pEnvEyeExt As IEnvelope
pEnvEyeExt = New Envelope
pEnvEyeExt.XMin = pEnvEyeFull.XMin + (pEnvMainExt.XMin - pEnvMainFull.XMin) / pEnvMainFull.Width * pEnvEyeFull.Width
pEnvEyeExt.XMax = pEnvEyeFull.XMax - (pEnvMainFull.XMax - pEnvMainExt.XMax) / pEnvMainFull.Width * pEnvEyeFull.Width
pEnvEyeExt.YMin = pEnvEyeFull.YMin + (pEnvMainExt.YMin - pEnvMainFull.YMin) / pEnvMainFull.Height * pEnvEyeFull.Height
pEnvEyeExt.YMax = pEnvEyeFull.YMax - (pEnvMainFull.YMax - pEnvMainExt.YMax) / pEnvMainFull.Height * pEnvEyeFull.Height
GetEyeRect = pEnvEyeExt
End Function
‘得到RGB颜色
Private Function GetRGBColor(ByVal pRed As Long, ByVal pGreen As Long, ByVal pBlue As Long) As IRgbColor
Dim pRGB As IRgbColor
pRGB = New RgbColor
pRGB.Red = pRed
pRGB.Green = pGreen
pRGB.Blue = pBlue
pRGB.UseWindowsDithering = True
GetRGBColor = pRGB
End Function
’得到鹰眼矩形框符号
Private Function GetEyeSym() As ISimpleFillSymbol
Dim pSym As ISimpleFillSymbol
pSym = New SimpleFillSymbol
Dim pLnSym As ISimpleLineSymbol
pLnSym = New SimpleLineSymbol
pLnSym.Color = Me.GetRGBColor(255, 0, 0)
pLnSym.Style = esriSimpleLineStyle.esriSLSSolid
pLnSym.Width = 2
pSym.Color = Me.GetRGBColor(255, 0, 0)
pSym.Style = esriSimpleFillStyle.esriSFSBackwardDiagonal
pSym.Outline = pLnSym
GetEyeSym = pSym
End Function
‘mapEye.Refresh()事件激活了mapEye的OnAfterDraw事件 -> 开始绘制鹰眼矩形框
Private Sub mapEye_OnAfterDraw(ByVal sender As System.Object, ByVal e As ESRI.ArcGIS.Controls.IMapControlEvents2_OnAfterDrawEvent) Handles mapEye.OnAfterDraw
EyeRect = GetEyeRect()
EyeSym = GetEyeSym()
If Not EyeRect Is Nothing And Not EyeSym Is Nothing Then
mapEye.DrawShape(EyeRect, EyeSym)
End If
End Sub
'在主图（mapMain）上进行操作（放大，缩小，平抑等），激活了mapMain_OnAfterScreenDraw事件
Private Sub mapMain_OnAfterScreenDraw(ByVal sender As System.Object, ByVal e As ESRI.ArcGIS.Controls.IMapControlEvents2_OnAfterScreenDrawEvent) Handles mapMain.OnAfterScreenDraw
mapEye.Refresh()
End Sub
End Class
在为MapControl添加事件时，我发现了三个事件：OnAfterDraw，OnAfterScreenDraw，OnBeforeScreenDraw ；
经过调试，我发现三者的执行顺序是 OnBeforeScreenDraw -> OnAfterDraw -> OnAfterScreenDraw
OnBeforeScreenDraw 意思还比较好理解，意为“执行屏幕绘制钱”，OnAfterDraw 与 OnAfterScreenDraw就有点混淆了
于是，我进行了一些调整和实验，把 mapEye.Refresh() 放在了 mapMain_OnAfterDraw 事件中，结果程序顺利运行；
把 mapEye_OnAfterDraw() 事件改成为 mapEye_OnAfterScreenDraw() 事件，内容保持不变，结果程序没有现实鹰眼功能；
由此我大概猜想：鹰眼框的绘制是不是算作“屏幕上图形的绘制”，故只能在OnAfterScreenDraw前执行，而主图上的一系列操作只要能够激发
mapEye.Refresh()就可以了，放在 mapMain_OnAfterScreenDraw 或是 mapMain_OnAfterDraw 中都是一样
关于MapControl的三个事件OnAfterDraw，OnAfterScreenDraw，OnBeforeScreenDraw 还望大家予以更详尽，更深入的讨论和讲解～～～
