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VB如何拦截键盘输入

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VB如何拦截键盘输入
Option Explicit

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
Declare Function UnhookWindowsHookEx Lib "user32" _
(ByVal hHook As Long) As Long
Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, _
ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long

Public hnexthookproc As Long
Public Const HC_ACTION = 0
Public Const WH_KEYBOARD = 2

Public Sub UnHookKBD()
If hnexthookproc <> 0 Then
UnhookWindowsHookEx hnexthookproc
hnexthookproc = 0
End If
End Sub
Public Function EnableKBDHook()
If hnexthookproc <> 0 Then
Exit Function
End If
hnexthookproc = SetWindowsHookEx(WH_KEYBOARD, AddressOf _
MyKBHFunc, App.hInstance, 0)
If hnexthookproc <> 0 Then
EnableKBDHook = hnexthookproc
End If
End Function
Public Function MyKBHFunc(ByVal iCode As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
'这叁个参数是固定的,不能动,而MyKBHFunc这个名称只要和
'SetWindowsHookex()中 AddressOf後的名称一样便可,不一定叫什麽
'wParam 是传入按了哪个key的virtual-key code

'如果您将以下的两行unmark则所有键盘的输入皆没有作用
'MyKBHFunc = 1 '吃掉讯息
'Exit Function

MyKBHFunc = 0 '讯息要处理
If iCode < 0 Then
MyKBHFunc = CallNextHookEx(hnexthookproc, iCode, wParam, lParam)
Exit Function
End If
If wParam = vbKeySnapshot Then '侦测 有没有按到PrintScreen键
MyKBHFunc = 1 '在这个Hook便吃掉这个讯息
Debug.Print "haha"
Else
Call CallNextHookEx(hnexthookproc, iCode, wParam, lParam)
End If
End Function

'以下在Form
Private Sub Form_Load()
Call EnableKBDHook
End Sub

Private Sub Form_Unload(Cancel As Integer)
Call UnHookKBD
End Sub

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