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Q141024: How to Start a Visual Basic Screen Saver Using SendMessage API

Article: Q141024
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0
Operating System(s): 
Keyword(s): kbcode
Last Modified: 20-FEB-2002

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

The sample code below shows how to start a Visual Basic screen saver by sending
a Windows message to the Control-menu box on a form.

MORE INFORMATION
================

Microsoft Windows starts screen savers through the System-menu box on a form.
The System-menu box is also known as the Control-menu box in Visual Basic. You
can send Windows messages to the Control-menu box by using the SendMessage
Windows API (application programming interface) function.

  [general declarations]
  #If Win32 Then
      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
      Const WM_SYSCOMMAND = &H112&
      Const SC_SCREENSAVE = &HF140&
  #Else
      Private Declare Function SendMessage Lib "User" (ByVal _         hWnd
  As Integer, ByVal wMsg As Integer, ByVal wParam As _             Integer,
  lParam As Any) As Long
      Const WM_SYSCOMMAND = &H112
      Const SC_SCREENSAVE = &HF140&
  #End If

  Private Sub Command1_Click()
      Dim result As Long
      result = SendMessage(Form1.hWnd, WM_SYSCOMMAND, _
       SC_SCREENSAVE, 0&)
  End Sub

REFERENCES
==========

You can find two sample programs and a complete explanation showing how to write
your own screen savers in Visual Basic in the following book:

"Visual Basic Workshop 3.0" by John C. Craig, published by Microsoft Press.

Additional query words: 3.00 4.00 vb4win vb4all .SCR TOPMOST SETWINDOWPOS SCRNSAVE timer

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Keywords          : kbcode 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : :4.0

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