在運行時顯示或隱藏窗體的標題欄

領測軟件測試網 這則代碼告訴你如何在運行時顯示或隱藏窗體的標題欄。要使一個窗口的標題欄消失，你必須去掉control box、最大化按鈕和最小化按鈕，并且將caption設為空。不幸的是，VB中窗體的ControlBox、MinButton和MaxButton屬性在運行期是只讀的，因此，你只能在設計時做這些事。其實，只要能熟練操作關于窗口式樣的API，你同樣能在運行時辦到這一點。
　　新建一個項目，把以下代碼寫入窗體：

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

　　' 獲取窗口的位置：
　　GetWindowRect Me.hwnd, tR

　　' 調整標題欄是否可見：
　　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

' 重新設定窗口：
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中加一點代碼，因為客戶區的大小已經改變：
'Form_Resize

End Function


　　為了試驗一下代碼，在窗體上放一個CheckBox，將它的Value屬性設為1 (Checked)。然后寫入以下代碼：

Private Sub Check1_Click()
　　If (Check1.Value = Checked) Then
　　ShowTitleBar True
　　Else
　　ShowTitleBar False
End If
End Sub

　　運行，當你點擊這個CheckBox時，窗體的標題欄將會在隱藏或顯示之間切換。

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