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强制重画窗口某一区域

　　这个例子演示了如何强制重画窗口某一区域.有时这是很需要的,例如当你使用LockWindowUpdate API 函数来加快某一控件的数据加载速度时.

　　新建一个工程,添加一个模块,代码如下:

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

　　在窗体上放置一个按钮和列表框.使列表框足够大以便观察效果.然后添加以下代码:
Private Sub Command1_Click()
　RepaintWindow List1
End Sub
Private Sub Form_Load()
　Dim i As Long
　For i = 1 To 200
　　List1.AddItem "TestItem " & i
　Next i
End Sub