VB入门技巧N例(1)

1. 如何消除textbox中按下回车时的beep声？

1. Private Sub Text1_KeyPress(KeyAscii As Integer)
   
2.   If KeyAscii = 13 Then
   
3.      KeyAscii = 0
   
4.   End If
   
5. End Sub

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2.Textbox获得焦点时自动选中。

1. Private Sub Text1_GotFocus()
   
2.   Text1.SelStart = 0
   
3.   Text1.SelLength = Len(Text1.Text)
   
4. End Sub

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3.屏蔽textbox控件自身的右键菜单，并显示自己的菜单。
方法一：

1. Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y _
   
2. As Single)
   
3.    If Button = 2 Then
   
4.      Text1.Enabled = False
   
5.      Text1.Enabled = True
   
6.      PopupMenu mymenu
   
7.    End If
   
8. End Sub

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方法二：回调函数

1. module：
   
2. Option Explicit
   
3. Public OldWindowProc As Long ' 保存默认的窗口函数的地址
   
4. Public Const WM_CONTEXTMENU = &H7B ' 当右击文本框时，产生这条消息
   
5. Public Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hWnd _  
   
6. As Long, ByVal nIndex As Long) As Long
   
7. Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd _  As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
   
8. Private Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal _ lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
   
9. Public Function SubClass_WndMessage(ByVal hWnd As Long, ByVal Msg As Long, ByVal wp _
   
10. As Long, ByVal lp As Long) As Long
    
11. ' 如果消息不是WM_CONTEXTMENU，就调用默认的窗口函数处理
    
12. If Msg <> WM_CONTEXTMENU Then
    
13.    SubClass_WndMessage = CallWindowProc(OldWindowProc, hWnd, Msg, wp, lp)
    
14.    Exit Function
    
15. End If
    
16. SubClass_WndMessage = True
    
17. End Function
    
18. 窗体中：
    
19. Private Const GWL_WNDPROC = (-4)
    
20. Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y _  
    
21. As Single)
    
22. If Button = 1 Then Exit Sub
    
23.    oldWindowProc = GetWindowLong(Text1.hWnd, GWL_WNDPROC) ' 取得窗口函数的地址
    
24.       ' 用SubClass_WndMessage代替窗口函数处理消息
    
25.    Call SetWindowLong(Text1.hWnd, GWL_WNDPROC, AddressOf SubClass_WndMessage)
    
26. End Sub
    
27. Private Sub Text1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    
28.   If Button = 1 Then Exit Sub
    
29.     ' 恢复窗口的默认函数
    
30.     Call SetWindowLong(Text1.hWnd, GWL_WNDPROC, OldWindowProc)
    
31.     PopupMenu mymenu
    
32. End Sub

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4. 设置TEXTBOX为只读属性

1. Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd _
   
2. As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
   
3. Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd _ As Long, ByVal nIndex As Long) As Long
   
4. Private Const GWL_STYLE = (-16)
   
5. Private Const EM_SETREADONLY = &HCF
   
6. Private Sub Command1_Click()
   
7.   Dim l As Long
   
8.   If (GetWindowLong(Text1.hwnd, GWL_STYLE) And &H800) Then
   
9.      Text1.Text = "This is a read/write text box."   '文本窗口是只读窗口,设置为可读写窗口
   
10.      l = SendMessage(Text1.hwnd, EM_SETREADONLY, False, vbNull)
    
11.      Text1.BackColor = #ffffff   '将背景设置为白色
    
12.      Command1.Caption = "Read&Write"
    
13.    Else
    
14.      Text1.Text = "This is a readonly text box."    '文本窗口是可读写窗口,设置为只读窗口
    
15.      l = SendMessage(Text1.hwnd, EM_SETREADONLY, True, vbNull)
    
16.      Text1.BackColor = vbInactiveBorder   '将背景设置为灰色
    
17.      Command1.Caption = "&ReadOnly"
    
18.   End If
    
19. End Sub

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