VB入门技巧多例3.doc

7.只容许运行一个程序实例（利用互斥体） 选择启动对象为sub main() module: 1 Public Declare Function CreateMutex Lib kernel32 Alias CreateMutexA _ (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, ByVal lpName _ 2 As String) As Long 3 Public Type SECURITY_ATTRIBUTES 4 nLength As Long 5 lpSecurityDescriptor As Long 6 bInheritHandle As Long 7 End Type 8 Public Const ERROR_ALREADY_EXISTS = 183& 9 Private Sub Main() 10 Dim sa As SECURITY_ATTRIBUTES 11 sa.bInheritHandle = 1 12 sa.lpSecurityDescriptor = 0 13 sa.nLength = Len(sa) 14 Debug.Print CreateMutex(sa, 1, App.Title) 这一行可千万不能删除啊 15 Debug.Print Err.LastDllError 16 If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then 17 MsgBox More than one instance 18 Else 19 Form1.Show 20 End If 21 End Sub8.窗体标题栏闪烁 1 Option Explicit 2 Private Declare Function FlashWindow Lib user32 (ByVal hwnd As Long, ByVal bInvert _ 3 As Long) As Long 4 Private Sub tmrFlash_Timer() 5 Static mFlash As Boolean 6 FlashWindow hwnd, Not mFlash 7 End Sub8. 拷屏 1 方法一：利用模拟键盘 2 Private Declare Sub keybd_event Lib user32 (ByVal bVk As Byte, ByVal bScan As Byte, _ ByVal dwFlags As Long, ByVal dwExtraInfo As Long) 3 Const theScreen = 1 4 Const theForm = 0 5 Private Sub Command1_Click() 6 Call keybd_event(vbKeySnapshot, theForm, 0, 0) 若theForm改成theScreen则Copy整个Screen 7 DoEvents 8 Picture1.Picture = Clipboard.GetData(vbCFBitmap) 9 End Sub9. 为程序注册热键 1 方法一：修改注册表 2 Private Declare Function RegisterHotKey Lib user32 (ByVal hWnd As Long, ByVal id _ 3 As Long, ByVal fsModifiers As Long, ByVal vk As Long) As Long 4 Private Declare Function UnregisterHotKey Lib user32 (ByVal hWnd As Long, ByVal id _ 5 As Long) As Long 6 Private Declare Function PeekMessage Lib user32 Alias PeekMessageA (lpMsg As Msg, _ ByVal hWnd As Long, ByVal wMsgFilterMin As Long, ByVal wMsgFilterMax As Long, ByVal _ wRemoveMsg As Long) As Long 7 Private Declare Function WaitMessage Lib user32 () As Long 8 Private Type POINTAPI 9 x As Long 10 y As Long 11 End Type 12 Private Type Msg 13 hWnd As Long 14 Message As Long 15 wParam As Long 16 lParam As Long 17 time As Long 18 pt As POINTAPI 19 End Type 20 声明常数 21 Private Const MOD_ALT = &H1 22 Private Const MOD_CONTROL = &H2 23 Private Const MOD_SHIFT = &H4 24 Private Const PM_REMOVE = &H1 25 Private Const WM_HOTKEY = &H312 26 Private HotKey_Fg As Boolean 27 Private Sub Form_Load() 28 Dim Message As Msg 29 注册 Ctrl+Y 为热键 30 RegisterHotKey Me.hWnd, &HBFFF&, MOD_CONTROL, vbKeyY 31 RegisterHotKey Me.hWnd, &HBFF2&, MOD_CONTROL, vbKeyU 32 Me.Show 33 Form1.Hide 34 等待处理消息 35 HotKey_Fg = False 36 Do While Not HotKey_Fg 37 等待消息 38 WaitMessage 39 检查是否热键被按下 40 If PeekMessage(Message, Me.hWnd, WM_HOTKEY, WM_HOTKEY, PM_REMOVE) Then 41 Form1.Show 1 42 End If 43 转让控制权,允许操作系统处理其他事件 44 DoEvents 45 Loop 46 End Sub 47 Private Sub Form_Unload(Cancel As Integer) 48 HotKey_Fg = True 49 撤销热键的注册 50 Call UnregisterHotKey(Me.hWnd, &HBFFF&) 51 End Sub方法二：SendMessage 1 Private Declare Function SendMessage Lib user32 Alias SendMessageA (ByVal hwnd As _ Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long 2 Private Const WM_SETHOTKEY = &H32 3 Private Const HOTKEYF_SHIFT = &H1 4 Private Const HOTKEYF_ALT = &H4 5 Private S