by Craig Atkins (1 Submission)
Category: Miscellaneous
Compatability: Visual Basic 3.0
Difficulty: Beginner
Date Added: Wed 3rd February 2021
Rating: 
(3 Votes)
When you, for example, add listitems to a listbox or combo box Windows repaints the box after each addidtion. This takes up processing time, makes your app look bad (due to flickering) and if you add a lot of items it can take a long time(Especially if the Combo or Listbox Sorted properety is set to true) Windows provides an API called LockWindowUpdate that you can use to keep Windows from updating a control with a hWnd property. This code is a simple way to call that function.
Inputs
objX As Object (The object to lock, i.e combo1)
cLock As Boolean (True locks the object, False unlocks it)
Assumes
To use the sub use something like:
LockControl Combo1, True
..which will prevent the control called Combo1 from repainting hence loading about 30% faster in a non sorted Combo box when adding 10.000 items.
To make the control update again use this code:
LockControl Combo1, False
...which makes Windows update the control Combo1 once again.
Code Returns
Nothing
API DeclarationsOption Explicit
Declare Function LockWindowUpdate Lib "user32" (ByVal hwndLock As Long) _
As Long
'-- End --'
VBcodersPublic Sub LockControl(objX As Object, cLock As Boolean)
Dim i As Long
If cLock Then
' This will lock the control
LockWindowUpdate objX.hWnd
Else
' This will unlock controls
LockWindowUpdate 0
objX.Refresh
End If
End sub
'-- End --'