MapXtreme开发经验分享-实现鹰眼

由于MapXtreme没有提供鹰眼控件，需要自己来写。实现鹰眼有两个步骤：

1）在地图的视图改变的时候根据地图当前的边距生成一个矩形框，然后把这个矩形框绘制到鹰眼窗口上。

2）根据用户在鹰眼窗口上点击的位置，同步显示地图窗口对应的位置。

VB.NET代码如下：

' 更新鹰眼图
Private Sub UpdateEyeMap()
Try
Dim tblRect As Table
tblRect = Session.Current.Catalog.GetTable("TempRect")
If Not tblRect Is Nothing Then
tblRect.Close()
End If

Dim tblInfo As TableInfo
tblInfo = TableInfoFactory.CreateTemp("TempRect")
Dim tblSessionInfo As TableSessionInfo = New TableSessionInfo()

tblRect = Session.Current.Catalog.CreateTable(tblInfo, tblSessionInfo)
Dim feaLayer As FeatureLayer = New FeatureLayer(tblRect)
MapControl_EagleEye.Map.Layers.Add(feaLayer)

'实时在鹰眼临时表图上画矩形
tblRect = Session.Current.Catalog.GetTable("TempRect")
CType(tblRect, ITableFeatureCollection).Clear()

'设置矩形的样式
Dim rect As MapInfo.Geometry.DRect = MapControl1.Map.Bounds
Dim feageo As FeatureGeometry = New MapInfo.Geometry.Rectangle(MapControl1.Map.GetDisplayCoordSys(), rect)
Dim simLineStyle As SimpleLineStyle = New SimpleLineStyle(New LineWidth(2, MapInfo.Styles.LineWidthUnit.Point), 2, System.Drawing.Color.Red)
Dim simInterior As SimpleInterior = New SimpleInterior(9, System.Drawing.Color.Gray, System.Drawing.Color.Green, True)
Dim comStyle As CompositeStyle = New CompositeStyle(New AreaStyle(simLineStyle, simInterior), Nothing, Nothing, Nothing)

'将矩形插入到图层中
Dim fea As Feature = New Feature(feageo, comStyle)
tblRect.InsertFeature(fea)

'重新定位鹰眼图的中心
MapControl_EagleEye.Map.Center = Map.Center
MapControl_EagleEye.Map.Layers("TempRect").Invalidate()

Catch ex As Exception
MessageBox.Show("鹰眼显示错误：" + ex.Message)
End Try
End Sub

Private Sub Map_ViewChanged(ByVal sender As System.Object, ByVal e As MapInfo.Mapping.ViewChangedEventArgs)
UpdateEyeMap()
End Sub

Private Sub MapControl_EagleEye_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MapControl_EagleEye.Click

Dim DisplayPoint As System.Drawing.PointF = New PointF(CType(e, System.Windows.Forms.MouseEventArgs).X, CType(e, System.Windows.Forms.MouseEventArgs).Y)
Dim MapPoint As New MapInfo.Geometry.DPoint()
Dim converter As MapInfo.Geometry.DisplayTransform = Me.MapControl_EagleEye.Map.DisplayTransform
converter.FromDisplay(DisplayPoint, MapPoint)
Map.Center = MapPoint
End Sub