Custom subtyped command and tool
PolyFeedbackTools.vb
' Copyright 2012 ESRI
' 
' All rights reserved under the copyright laws of the United States
' and applicable international laws, treaties, and conventions.
' 
' You may freely redistribute and use this sample code, with or
' without modification, provided you include the original copyright
' notice and use restrictions.
' 
' See the use restrictions.
' 

Imports System.Runtime.InteropServices
Imports System.Drawing
Imports ESRI.ArcGIS.ADF.BaseClasses
Imports ESRI.ArcGIS.ADF.CATIDs
Imports ESRI.ArcGIS.Framework
Imports ESRI.ArcGIS.ArcMapUI
Imports System.Windows.Forms
Imports ESRI.ArcGIS.SystemUI
Imports ESRI.ArcGIS.Display
Imports ESRI.ArcGIS.Geometry

<ComClass(PolyFeedbackTools.ClassId, PolyFeedbackTools.InterfaceId, PolyFeedbackTools.EventsId), _
 ProgId("CommandSubtypeVB.PolyFeedbackTools")> _
Public NotInheritable Class PolyFeedbackTools
    Inherits BaseTool
    Implements ICommandSubType

#Region "COM GUIDs"
    ' These  GUIDs provide the COM identity for this class 
    ' and its COM interfaces. If you change them, existing 
    ' clients will no longer be able to access the class.
    Public Const ClassId As String = "5846f005-22f6-4ee6-b563-75a08b0d219e"
    Public Const InterfaceId As String = "a86f93a9-867f-4caa-aa6b-ffa8ce132ba4"
    Public Const EventsId As String = "6f6ee1b5-8c27-403e-94e0-5e975511d6a2"
#End Region

#Region "COM Registration Function(s)"
    <ComRegisterFunction(), ComVisibleAttribute(False)> _
    Public Shared Sub RegisterFunction(ByVal registerType As Type)
        ' Required for ArcGIS Component Category Registrar support
        ArcGISCategoryRegistration(registerType)

        'Add any COM registration code after the ArcGISCategoryRegistration() call

    End Sub

    <ComUnregisterFunction(), ComVisibleAttribute(False)> _
    Public Shared Sub UnregisterFunction(ByVal registerType As Type)
        ' Required for ArcGIS Component Category Registrar support
        ArcGISCategoryUnregistration(registerType)

        'Add any COM unregistration code after the ArcGISCategoryUnregistration() call

    End Sub

#Region "ArcGIS Component Category Registrar generated code"
    Private Shared Sub ArcGISCategoryRegistration(ByVal registerType As Type)
        Dim regKey As String = String.Format("HKEY_CLASSES_ROOT\CLSID\{{{0}}}", registerType.GUID)
        MxCommands.Register(regKey)

    End Sub
    Private Shared Sub ArcGISCategoryUnregistration(ByVal registerType As Type)
        Dim regKey As String = String.Format("HKEY_CLASSES_ROOT\CLSID\{{{0}}}", registerType.GUID)
        MxCommands.Unregister(regKey)

    End Sub

#End Region
#End Region

    Private m_application As IApplication

    Private m_polygonFeedback As INewPolygonFeedback
    Private m_screenDisplay As IScreenDisplay
    Private m_maxSides As Integer   'max allowed sides
    Private m_currentSides As Integer 'number of sides added to the feedback

    ' A creatable COM class must have a Public Sub New() 
    ' with no parameters, otherwise, the class will not be 
    ' registered in the COM registry and cannot be created 
    ' via CreateObject.
    Public Sub New()
        MyBase.New()

        'Set up common properties
        MyBase.m_category = ".NET Samples"
        MyBase.m_cursor = Cursors.Cross
    End Sub

    Public Overrides Sub OnCreate(ByVal hook As Object)
        If Not hook Is Nothing Then
            m_application = TryCast(hook, IApplication)

            If TypeOf hook Is IMxApplication Then
                MyBase.m_enabled = True
            Else
                MyBase.m_enabled = False
            End If
        End If
    End Sub

    Public Overrides Sub OnClick()
        'prepare screen display for mouse interaction
        Dim mxDoc As IMxDocument = DirectCast(m_application.Document, IMxDocument)
        m_screenDisplay = mxDoc.ActiveView.ScreenDisplay
    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 IPoint = m_screenDisplay.DisplayTransformation.ToMapPoint(X, Y)

            If m_polygonFeedback Is Nothing Then
                m_currentSides = 0
                m_polygonFeedback = New NewPolygonFeedbackClass()
                m_polygonFeedback.Display = m_screenDisplay

                m_polygonFeedback.Start(cursorPoint)
            Else
                m_polygonFeedback.AddPoint(cursorPoint)
            End If

            m_currentSides += 1
            If m_currentSides = m_maxSides Then 'Finish
                Dim polygon As IPolygon = m_polygonFeedback.Stop()

                'Report area on status bar
                Dim feedBackArea As IArea = DirectCast(polygon, IArea)
                m_application.StatusBar.Message(0) = "Feedback area = " + Math.Abs(feedBackArea.Area).ToString()

                m_polygonFeedback = Nothing
            Else
                'Report vertex remaining
                m_application.StatusBar.Message(0) = String.Format("Feedback: {0} point(s) remaining", m_maxSides - m_currentSides)
            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 m_polygonFeedback IsNot Nothing Then
            Dim cursorPoint As IPoint = m_screenDisplay.DisplayTransformation.ToMapPoint(X, Y)
            m_polygonFeedback.MoveTo(cursorPoint)
        End If
    End Sub

    Public Overrides Function Deactivate() As Boolean
        'Clean up
        If m_polygonFeedback IsNot Nothing Then
            m_polygonFeedback.Stop()
            m_polygonFeedback = Nothing
        End If
        m_screenDisplay = Nothing

        Return True
    End Function

#Region "ICommandSubType implementation"
    Public Function GetCount() As Integer Implements ESRI.ArcGIS.SystemUI.ICommandSubType.GetCount
        Return 3
    End Function

    Public Sub SetSubType(ByVal SubType As Integer) Implements ESRI.ArcGIS.SystemUI.ICommandSubType.SetSubType
        'Set up bitmap, caption, tooltip etc.
        If MyBase.Bitmap = 0 Then
            Select Case SubType
                Case 1
                    MyBase.m_bitmap = My.Resources.FeedBack3
                Case 2
                    MyBase.m_bitmap = My.Resources.FeedBack4
                Case 3
                    MyBase.m_bitmap = My.Resources.FeedBack5
            End Select
        End If

        MyBase.m_name = String.Format("VBNETSamples_SubTypeTool{0}", SubType)

        m_maxSides = SubType + 2 '3, 4 or 5 sides
        MyBase.m_caption = String.Format("{0} sides feedback (VB.Net)", m_maxSides)
        MyBase.m_toolTip = String.Format("{0} sides feedback", m_maxSides)
        MyBase.m_message = String.Format("Tool demonstrating {0} sides polygon feedback", m_maxSides)
    End Sub
#End Region
End Class