Skapat verktyg med IDisplayFeedback.

Vi har problem med standard mätverktyget i ArcGIS engine. Bug in ControlMapMeasureTool? “Measure An Area” creates a duplicate dialog in ArcGIS Engine 10 Så jag har suttit efter tips från Kirk och labbat lite hur man kan skapa egna verktyg med IDisplayFeedback. Hittade ett bra exempel Sample: Custom subtyped command and tool som visade hur man ska göra. Skapar man en ny verktygsklass, så kan man överlagra på det här sättet för att få ett verktyg som mäter areal:

 Private m_polygonFeedback As INewPolygonFeedback  
 Private m_screenDisplay As IScreenDisplay  
   
 Private m_hookHelper As IHookHelper  
   
   
 Public Overrides Sub OnCreate(ByVal hook As Object)  
   If (m_hookHelper Is Nothing) Then m_hookHelper = New HookHelperClass  
   
   If Not hook Is Nothing Then  
    m_hookHelper.Hook = hook  
   End If  
 End Sub  
   
 Public Overrides Sub OnClick()  
   m_screenDisplay = m_hookHelper.ActiveView.ScreenDisplay  
 End Sub  
   
 Public Overrides Sub OnDblClick()  
   Dim polygon As IPolygon = m_polygonFeedback.Stop()  
   MsgBox("Area: " & CType(polygon, IArea).Area)  
   m_polygonFeedback = Nothing  
 End Sub  
   
 Public Overrides Sub OnMouseDown(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Integer, ByVal Y As Integer)  
   If Button = 1 Then  
    Dim cursorPoint As ESRI.ArcGIS.Geometry.IPoint = m_screenDisplay.DisplayTransformation.ToMapPoint(X, Y)  
   
    If m_polygonFeedback Is Nothing Then  
      m_polygonFeedback = New NewPolygonFeedbackClass()  
      m_polygonFeedback.Display = m_screenDisplay  
   
      m_polygonFeedback.Start(cursorPoint)  
    Else  
      m_polygonFeedback.AddPoint(cursorPoint)  
    End If  
   
   End If  
 End Sub  
   
 Public Overrides Sub OnMouseMove(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Integer, ByVal Y As Integer)  
   If Not m_polygonFeedback Is Nothing Then  
    Dim cursorPoint As ESRI.ArcGIS.Geometry.IPoint = m_screenDisplay.DisplayTransformation.ToMapPoint(X, Y)  
    m_polygonFeedback.MoveTo(cursorPoint)  
   End If  
 End Sub