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| How to intercept window messages sent to VFP form |
User rating: 0/10 (0 votes) | | |
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| Before you begin: |
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Before testing this code download WinProcXT.dll to a local directory and register it:
regsvr32 c:\temp\WinProcXT.dll
Change "c:\temp" to the name of a directory where you copied the DLL file.
This is an ActiveX DLL. The VB code is available here.
The DLL reassignes the WindowProc address of the VFP form to its own function and sends system messages to a text file. Change in the following program code the "c:\temp\log.txt" to any appropriate file name.
Every system message has three parameters to be saved: message identifier, first message parameter, second message parameter.
Run the following code. Right after you close the form a list of system messages saved during its execution appears. Usually this list ends with message identifiers 2 (WM_DESTROY) and 130 (WM_NCDESTROY).
List of some message identifiers is available here.
* * *
For VFP9 use BINDEVENT() to trap Windows messages. |
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PUBLIC objForm
objForm = CreateObject("TForm")
objForm.Visible = .T.
DEFINE CLASS TForm As Form
Width=460
Height=300
AutoCenter=.T.
Caption=" Recording Window Messages"
KeyPreview=.T.
recorder=.F.
hWindow=0
PROCEDURE Activate
IF THIS.hWindow = 0
DECLARE INTEGER GetFocus IN user32
THIS.hWindow = GetFocus()
THIS.recorder = CreateObject("TRecorder",;
THIS.hWindow, "c:\temp\log.txt")
ENDIF
PROCEDURE KeyPress
LPARAMETERS nKeyCode, nShiftAltCtrl
IF nKeyCode = 27
ThisForm.Release
ENDIF
ENDDEFINE
DEFINE CLASS TRecorder As Custom
hWindow=0
LogFile=""
ole=.F.
PROCEDURE Init (hWnd, lcFileName)
THIS.LogFile = lcFileName
THIS.hWindow = hWnd
ON ERROR ?? Chr(7)
THIS.ole = CreateObject("WinProcXT.WinProc")
ON ERROR
IF TYPE("THIS.ole") <> "O"
RETURN .F.
ENDIF
WITH THIS.ole
.StartService (THIS.hWindow, THIS.LogFile)
IF Not .IsRunning
RETURN .F.
ENDIF
ENDWITH
PROCEDURE Destroy
THIS.ole.StopService
IF FILE (THIS.LogFile)
CREATE CURSOR csMessages (msg N(16), wParam N(16), lParam N(16))
APPEND FROM (THIS.LogFile) TYPE DELIMITED WITH TAB
GO TOP
BROWSE NORMAL NOWAIT
ENDIF
ENDDEFINE
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User rating: 0/10 (0 votes) | | | 1207 bytes
Created: 2002-04-21 18:35:15
Modified: 2005-10-10 11:22:17
Visits in 7 days: 49 |
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The WindowProc function is an application-defined function that processes messages sent to a window.
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| Word Index links for this example: |
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Enumerating connections made to a shared resource for the local computer (WinNT only) 
