Force an area of a Window to Repaint

Author:

Steve McMahon(steve@vbaccelerator.com)

Keywords:

API,GDI,Graphics,Windows Controls

Updated:

01/08/98

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This sample shows how to force an area of a window to repaint. Sometimes this is necessary, particularly when you're experimenting with owner draw control techniques, or when using the LockWindowUpdate API call to improve the speed at which a control fills with data.

Create a new project, add a module and paste in the code below:

Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type
Private Type POINTAPI
    X As Long
    Y As Long
End Type
Private Declare Function GetWindowRect Lib "user32" (ByVal hWnd As Long, lpRect As RECT) As Long
Private Declare Function GetClientRect Lib "user32" (ByVal hWnd As Long, lpRect As RECT) As Long
Private Declare Function InvalidateRect Lib "user32" (ByVal hWnd As Long, lpRect As RECT, ByVal bErase As Long) As Long
Private Declare Function ScreenToClient Lib "user32" (ByVal hWnd As Long, lpPoint As POINTAPI) As Long

Public Sub RepaintWindow( _
        ByRef objThis As Object, _
        Optional ByVal bClientAreaOnly As Boolean = True _
    )
Dim tR As RECT
Dim tP As POINTAPI
    If (bClientAreaOnly) Then
        GetClientRect objThis.hWnd, tR
    Else
        GetWindowRect objThis.hWnd, tR
        tP.X = tR.Left: tP.Y = tR.Top
        ScreenToClient objThis.hWnd, tP
        tR.Left = tP.X: tR.Top = tP.Y
        tP.X = tR.Right: tP.Y = tR.Bottom
        ScreenToClient objThis.hWnd, tP
        tR.Right = tP.X: tR.Bottom = tP.Y
    End If
    InvalidateRect objThis.hWnd, tR, 1
   
End Sub
       

Related Tips and Articles:

• Prevent a window from repainting