Difference between revisions of "Subclassing in .NET"

Revision as of 13:16, 8 May 2008

'General class to subclass any window (control,form..etc)
Public Class SubclassWindow
        Inherits NativeWindow
        Dim m_Msg As Integer = -1
        Dim bCatchMsg As Boolean = False
        Public Event OnProcessMessage(ByRef m As System.Windows.Forms.Message)
        Public Property CatchMessage() As Integer
            Get
                Return m_Msg
            End Get
            Set(ByVal Value As Integer)
                m_Msg = Value
                bCatchMsg = True
            End Set
        End Property
        Protected Overloads Overrides Sub WndProc(ByRef m As Message)
            If bCatchMsg AndAlso m.Msg = m_Msg Then
                RaiseEvent OnProcessMessage(m)
                If Not m.Result.Equals(IntPtr.Zero) Then
                    Return
                End If
            End If
            MyBase.WndProc(m)
        End Sub
End Class

'###  Example How to use it #####'
'declare  
Dim withevents oSubclassTest as SubclassWindow

'then put the code in InitializeComponent or where you need
oSubclassTest = New SubclassWindow
With oSubclassCalendar
 .CatchMessage = WM_LBUTTONDOWN  ' or other message
 .AssignHandle(textbox1.Handle) ' or any control/form..etc
End With

'then catch the specific message within OnProcessMessage event
Private Sub SubclassWindow_OnProcessMessage(ByRef m As System.Windows.Forms.Message) Handles oSubclassTest.OnProcessMessage
        'insert your code here (processing...etc)
        '''''''''

        'to stop the message,set Result property: 
        m.Result = New IntPtr(1)
End Sub