IOleInPlaceObjectWindowlessVB interface

A Visual Basic-style version of IOleInPlaceObjectWindowless.OnWindowMessage, which a class can implement.

IOleInPlaceObjectWindowlessVB is not a Windows interface. It has the interface identifier 061D3A2F-A213-4016-9756-B89140604819 and extends stdole.IDispatch. It is not declared [OleAutomation(False)], as the package’s Windows interfaces are. Its one method has the dispatch identifier 1 ([DispId(1)]).

It exists because IOleInPlaceObjectWindowless has [PreserveSig] members, which a twinBASIC class cannot implement. This interface has one Sub that corresponds to the OnWindowMessage method of that interface, with signature types that Visual Basic code uses. GetDropTarget has no counterpart.

Methods

OnWindowMessage 

[DispId(1)]
Sub OnWindowMessage(ByRef Handled As Boolean, ByVal wMsg As Long, ByVal wParam As LongPtr, ByVal lParam As LongPtr, ByRef Result As LongPtr)

Receives a window message that a container sends to an object that is active in place and has no window. wMsg is the message identifier, and wParam and lParam are the parameters of the message.

Handled and Result are passed by reference, and the implementation sets them. Handled is a flag that an implementation which processed the message sets to True. Result corresponds to the result code that the Windows method returns through its last parameter.

Example

This class processes the left mouse button message, WM_LBUTTONDOWN (&H201), and leaves every other message to its container.

Class ClickHandler
    Implements IOleInPlaceObjectWindowlessVB

    Private Sub IOleInPlaceObjectWindowlessVB_OnWindowMessage(ByRef Handled As Boolean, ByVal wMsg As Long, ByVal wParam As LongPtr, ByVal lParam As LongPtr, ByRef Result As LongPtr) Implements IOleInPlaceObjectWindowlessVB.OnWindowMessage
        If wMsg = &H201 Then
            Handled = True
            Result = 0
        End If
    End Sub
End Class

A container passes it the messages it receives:

Dim w As IOleInPlaceObjectWindowlessVB = New ClickHandler
Dim handled As Boolean
Dim result As LongPtr

w.OnWindowMessage handled, &H201, 0, 0, result
Debug.Print handled  ' True

handled = False
w.OnWindowMessage handled, &H200, 0, 0, result
Debug.Print handled  ' False

See Also