problem with wm_gettext

Visual Basic

    Sponsored Links


  • 1. Click button in another app?
    Hi, I have done some database stuff with VB6 butt I have never tried to manipulate another program. I am using "Backup My PC" from STOMP. When you backup to a file, you have to click a button to create a new file once the target gets over 4 GB. Since STOMP doesn't seem to be interested in fixing this, I would like to make something that clicks that button when it pops up so it can be a truly unattended backup. Can anyone give me some pointers on how to accomplish this? Thanks, Dan
  • 2. Changing a property
    I'm trying to make an ocx control using vb6. Everything works fine, except for the following: When I change a control's property it doesn't get updated with thew new value inmediately. I have to execute the application where I placed the control in order to get ther new value applied visually(although internally is OK). The new value is persistent anyway. How can I get an inmediate visual change of the control when I change one of its visual properties at design time? Thank you. Rick.
  • 3. Create a Windows XP Compressed Folder (.zip File) with vb6?
    All, I posted this before and never really got a final response. Is it possible to create a Windows XP (or Server 2003) Compressed Folder programatically using VB6? I am looking for a way to do this without purchasing/downloading a third party ocx or dll. I imagine that it is possible through a set of API calls. Any and all related suggestions/tips are appreciated!!! Thanks!! Brian
  • 4. VB6 and on same machine
    Is OK to have VB6 and loaded on the same machine? I have to work on existing programs that are written in both versions. Thanks!
  • 5. Controlling serial comm
    I want to control the output of all 9 pins of the serial port on my PC during serial communication sessions. I know how to transmit and recieve data (Pins 2 and 3) using the MSComm. But I still don't know how to set the Carrier Detect pin (pin number 1) to Low or High while I'm communicating with another computer over the serial port. I don't want to check its status, but rather to set its value.

problem with wm_gettext

Postby Jim Bauer » Sun, 25 Apr 2004 03:57:00 GMT

I am trying to get the text of a window by sending that window a
WM_GETTEXT message.
The below code compiles correctly, but the "buffer" string variable
I've declared is blank.

Private Declare Function SendMessage Lib "user32" Alias_
"SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam_
As Long, ByVal lParam As Long) As Long

Private Const WM_GETTEXT = &HD
Private Const wm_gettextlen = &HE

public function GetText(hwnd as long) as string
Dim buffer As String
SendMessage hwnd, WM_GETTEXT, wm_gettextlen, ByVal buffer
GetText = buffer
End Function

***END of code***
Any pointers as to what I'm doing wrong?
Cheers, Jim

Re: problem with wm_gettext

Postby Tom Esh » Sun, 25 Apr 2004 04:48:57 GMT

On Fri, 23 Apr 2004 18:57:00 GMT, Jim Bauer < XXXX@XXXXX.COM >

1) Your SendMessage declare is wrong for this case. lParam should be
ByVal As String, or simply As Any (specify ByVal in the call).

2) You must pre-allocate buffer to at least the number of chars
expected, iow at least what you tell it the size is in wParam. If
you've really no idea of the required size, you can use the
WM_GETTEXTLENGTH message. Note however this is a separate message and
requires a separate call. (Your wm_gettextlen const declare and usage
indicates you may be confused on this point.)

3) wParam should be the pre-allocated buffer size.

Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
	(ByVal hWnd As Long, ByVal wMsg As Long, _
	ByVal wParam As Long, lParam As Any) As Long

Dim Buffer As String
Dim lSize As Long
Dim lRet As Long

lSize = SendMessage(hwnd, WM_GETTEXTLENGTH, 0&, ByVal 0&)
Buffer = String(lSize + 1, 0)
lRet = SendMessage(hwnd, WM_GETTEXT, lSize, ByVal Buffer)
If lRet > 0 Then
	Buffer = Left$(Buffer, lRet)
End If

MVP - Visual Basic
(please post replies to the newsgroup)

Similar Threads:


I have written two standard apps (not ActiveX) in VB6 SP6.  These apps 
communicate with one another via SendMessage API utilizing hidden text boxes 

The scenario is the "server" app has a few hidden textboxes (channels) which 
it uses to send various commands to the "client" app.  When the server 
starts the client app (Shell, not ActiveX) it passes the wHnd to those 
textboxes as command line args.  The client app then while running (this app 
runs a never ending loop) at regular frequent intervals issues a SendMessage 
WM_GETXT to the various channels (depending on where in the processing loop 
it is) to get instructions from the server.  The client also issues 
SendMessage WM_SETTEXT messages (to a different window on the server) to 
provide status and progress info back to the server.

The problem is that it appears as though the client app hangs after issuing 
the WM_GETTEXT message until some event occurs on the client.  The event 
that I know will wake the client back up is a mouse_move over its form. 
This is a problem since the client has no reason to have a UI (it is a 
background process).  Any way here is the scenario; App1 (the server) starts 
and shell starts App2 (the client). App2 then goes into a polling loop 
polling the hidden text boxes on App1 for instructions.  For debugging 
purposes I have added a form to App2 that simply displays one text box for 
each hidden text box in App1 and populates those text boxes with the text 
commands received via SendMessage WM_GETTEXT calls.  With both windows 
(App1s and App2s) visible I click a button on App1 which sends a command to 
one of the hidden communication textboxes.  In the App2 window I should see 
the text displayed in the corresponding textbox.  I do not though, and 
infact it appears (from other debug messages which should but are not being 
shown in another textbox on App2) as though App2 is hung, however if I then 
move the mouse over App2's window the app un-hangs receives the command and 

Anyone have any thoughts on why this is happening?

Thanx in advance for your help
Steve result with WM_GETTEXT

3.WM_GETTEXT hangs up

Hi all

I noticed that when I try to get text from one particular window calling 
SendMessage(hWnd, WM_GETTEXT...
the application hangs up until I close it using Task Manager.
For all other windows this call works fine.
The window's class = "Shell Embedding", invisible, RECT=0,0,0,0
Any ideas?
Definitely, I didn't have this problem yesterday, because I tested my 
application sending this message to all windows in the desktop tree (about 
1060 of them).
By the way I've got only one window of this class.

Thank you

4.WM_GETTEXT function


Hi all,

I'm trying to capture the text from a popup window (i.e. a MsgBox). The code


Dim lHandle As Long
Dim length  As Long
Dim result  As Long
Dim strtmp  As String

lHandle = FindWindow(vbNullString, "Some Popup")

 If lHandle <> 0 Then

    length = SendMessage(lHandle, WM_GETTEXTLENGTH, ByVal 0, ByVal 0) + 1

    strtmp = Space(length - 1)
    result = SendMessage(lHandle, WM_GETTEXT, ByVal length, ByVal strtmp)

 End If

gives me the title of the popup window ('Some Popup') but not the msg on the
popup. How kan I get the message?


7. Unknown pointer problem between Visual Basic and C (problem solved)

8. problems converting C# code to (MSMQ formatter problem)

Return to Visual Basic


Who is online

Users browsing this forum: No registered users and 40 guest