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Expertise: Beginner
Aug 6, 1997



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Speedy List Boxes

One way to speed list-box loading is to eliminate the constant redrawing required while loading. You can do this by calling the LockWindowUpdate API. LockWindowUpdate accepts an HWND as a parameter to start the lock and a zero parameter to unlock it. Only one window can be locked at a time. If LockWIndowUpdate is called with another HWND, the currently locked window will be unlocked. To run this sample, put a command button and a list box on a form and paste in this code. Your code may not require the DoEvents within the loop that adds items, and a tight basic loop will keep the list from updating. However, there are times when the DoEvents is required.
 Private Declare Function LockWindowUpdate Lib "user32" (ByVal hwndLock As Long) As Long

Private Sub Command1_Click()
	Dim i%
	LockWindowUpdate (List1.hWnd)
	For i% = 1 To 1000
		List1.AddItem Str$(i%)
	LockWindowUpdate (0&)
End Sub
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