vb:如何禁止鼠标指针进入某个区域

我们知道ClipCursor可以将指针限制到指定区域，那么如何反其道而为之，禁止鼠标进入某个区域呢，答案是用鼠标钩子，在WIN NT 4.0 SP3以上系统可以用WH_MOUSE_LL这个钩子实现，这个钩子的特殊之处是不需要用dll，另外，这个钩子用到了一个结构体，简单说明一下：
typedef struct {
POINT pt;
DWORD mouseData;
DWORD flags;
DWORD time;
ULONG_PTR dwExtraInfo;
} MSLLHOOKSTRUCT, *PMSLLHOOKSTRUCT;

Members


好了废话少说，看代码：
一个模块，一个窗体（名为Form1）

模块代码：
Option Explicit
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef Destination As Any, ByRef Source As Any, ByVal Length As Long)
Private Declare Function PtInRect Lib "user32" (lpRect As RECT, ByVal x As Long, ByVal y As Long) As Long
Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Private Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, lparam As Any) As Long
Private Const HC_ACTION = 0
Private Const WH_MOUSE_LL As Long = 14
Private Const WM_MOUSEMOVE = &H200

Public 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 Type MSLLHOOKSTRUCT
pt As POINTAPI
mouseData As Long
Flags As Long
time As Long
dwExtraInfo As Long
End Type

Public hHook As Long
Public hRT As RECT
Public Sub EnableHook(hRect As RECT)
hRT = hRect
If hHook = 0 Then
hHook = SetWindowsHookEx(WH_MOUSE_LL, AddressOf HookProc, App.hInstance, 0)
End If
End Sub
Public Sub FreeHook()
If hHook <> 0 Then
Call UnhookWindowsHookEx(hHook)
hHook = 0
End If
End Sub

Public Function HookProc(ByVal nCode As Long, ByVal wParam As Long, ByVal lparam As Long) As Long
Dim typMHS As MSLLHOOKSTRUCT, pt As POINTAPI
If nCode < 0 Then
HookProc = CallNextHookEx(hHook, nCode, wParam, lparam)
Exit Function
End If
If wParam = WM_MOUSEMOVE Then
Call CopyMemory(typMHS, ByVal lparam, LenB(typMHS))
pt = typMHS.pt
If PtInRect(hRT, pt.x, pt.y) <> 0 Then
HookProc = 1 '取消原本要完成的動作
Else
Form1.Caption = "mouse Cursor at " + CStr(pt.x) + "," + CStr(pt.y)
HookProc = 0 '令待完成的動作繼續完成
End If
End If
End Function

窗体代码：
Option Explicit
Const HWND_TOPMOST = -1
Const HWND_NOTOPMOST = -2
Const SWP_NOSIZE = &H1
Const SWP_NOMOVE = &H2
Const SWP_NOACTIVATE = &H10
Const SWP_SHOWWINDOW = &H40
Private Declare Sub 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)

Private Sub Form_Activate()
'设置窗口为TOPMOST窗口，目的是便于观察
SetWindowPos Me.hWnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE Or SWP_SHOWWINDOW Or SWP_NOMOVE Or SWP_NOSIZE
End Sub
Private Sub Form_Load()
Dim RT As RECT
With RT
.Left = 0
.Right = 400
.Top = 0
.Bottom = 300
End With
EnableHook RT
End Sub

Private Sub Form_Unload(Cancel As Integer)
FreeHook
End Sub

需要指出的是VB自带的api浏览器中的PtInRect声明有问题，调用它的时候尽管不报错，但不能判断指定点是否位于RECT内，为此修改了它的声明

另外，我这段程序是禁止鼠标指针进入(0,0)-(400,300)这个区域，在调试的时候可能窗体的关闭按钮正好位于这一区域，这时候，记得按下 alt+F4关闭窗口