这则代码告诉你如何在运行时显示或隐藏窗体的标题栏。要使一个窗口的标题栏消失,你必须去掉control box、最大化按钮和最小化按钮,并且将caption设为空。不幸的是,VB中窗体的ControlBox、MinButton和MaxButton属性在运行期是只读的,因此,你只能在设计时做这些事。其实,只要能熟练操作关于窗口式样的API,你同样能在运行时办到这一点。 新建一个项目,把以下代码写入窗体:
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" _ (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" _ (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Const GWL_STYLE = (-16) Private Const WS_CAPTION = &HC00000 ´ WS_BORDER 或 WS_DLGFRAME Private Const WS_MAXIMIZEBOX = &H10000 Private Const WS_MINIMIZEBOX = &H20000 Private Const WS_SYSMENU = &H80000
Private Declare Function SetWindowPos Lib "user32" _ (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, _ ByVal y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
Private Enum ESetWindowPosStyles SWP_SHOWWINDOW = &H40 SWP_HIDEWINDOW = &H80 SWP_FRAMECHANGED = &H20 ´ The frame changed: send WM_NCCALCSIZE SWP_NOACTIVATE = &H10 SWP_NOCOPYBITS = &H100 SWP_NOMOVE = &H2 SWP_NOOWNERZORDER = &H200 ´ Don´t do owner Z ordering SWP_NOREDRAW = &H8 SWP_NOREPOSITION = SWP_NOOWNERZORDER SWP_NOSIZE = &H1 SWP_NOZORDER = &H4 SWP_DRAWFRAME = SWP_FRAMECHANGED HWND_NOTOPMOST = -2 End Enum
Private Declare Function GetWindowRect Lib "user32" (ByVal hwnd As Long, lpRect As RECT) As Long Private Type RECT Left As Long Top As Long Right As Long Bottom As Long End Type
Private Function ShowTitleBar(ByVal bState As Boolean) Dim lStyle As Long Dim tR As RECT
´ 获取窗口的位置: GetWindowRect Me.hwnd, tR
´ 调整标题栏是否可见: lStyle = GetWindowLong(Me.hwnd, GWL_STYLE) If (bState) Then Me.Caption = Me.Tag If Me.ControlBox Then lStyle = lStyle Or WS_SYSMENU End If If Me.MaxButton Then lStyle = lStyle Or WS_MAXIMIZEBOX End If If Me.MinButton Then lStyle = lStyle Or WS_MINIMIZEBOX End If If Me.Caption <> "" Then lStyle = lStyle Or WS_CAPTION End If Else Me.Tag = Me.Caption Me.Caption = "" lStyle = lStyle And Not WS_SYSMENU lStyle = lStyle And Not WS_MAXIMIZEBOX lStyle = lStyle And Not WS_MINIMIZEBOX lStyle = lStyle And Not WS_CAPTION End If SetWindowLong Me.hwnd, GWL_STYLE, lStyle
´ 重新设定窗口: SetWindowPos Me.hwnd, 0, tR.Left, tR.Top, tR.Right - tR.Left, tR.Bottom - tR.Top, SWP_NOREPOSITION Or SWP_NOZORDER Or SWP_FRAMECHANGED Me.Refresh
´ 你可能需要在Form_Resize中加一点代码,因为客户区的大小已经改变: ´Form_Resize
End Function
为了试验一下代码,在窗体上放一个CheckBox,将它的Value属性设为1 (Checked)。然后写入以下代码:
Private Sub Check1_Click() If (Check1.Value = Checked) Then ShowTitleBar True Else ShowTitleBar False End If End Sub
运行,当你点击这个CheckBox时,窗体的标题栏将会在隐藏或显示之间切换。
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