arindam_bh
asked on
Keyboard & Mouse Hook
Hello friends,
How to hook the keyboard and mouse using VB .net. I am developing a COM application involving Microsoft Internet Explorer and I needed to trap the keys & mouse and selectively allow the user to be able to type certain moments and prevent him in certain moments. Can someone provide the skeletal structure for doing the same? At present I am using the following skeleton, but it is not able to hook.
Can someone please help.
Thanks in Advance
Arindam
Friend Class frmMain
Inherits System.Windows.Forms.Form
Public Shared hHook As Long = 0
Public Const WH_KEYBOARD As Short = 2
Public Const KBH_MASK As Integer = &H20000000
Public Const HC_ACTION = 0
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_LBUTTONUP = &H202
Public Const WM_RBUTTONDOWN = &H204
Public Const WH_MOUSE = 7
Public Delegate Function CallBack(ByVal nCode As Integer, ByVal wParam As Long, ByVal lParam As Long) As Integer
Public HookProc As CallBack
Public Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Integer, ByVal HookProc As CallBack, ByVal hInstance As Long, ByVal wParam As Integer) As Integer
Public Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer
Const EM_UNDO As Short = &HC7s
Private Declare Function OSWinHelp Lib "user32" Alias "WinHelpA" (ByVal hwnd As Integer, ByVal HelpFile As String, ByVal wCommand As Short, ByRef dwData As Integer) As Short
Private Sub frmMain_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
'Some Code
installHook()
End Sub
Public Sub installHook()
HookProc = New CallBack(AddressOf HookHandlerClass.HookProc)
UnhookWindowsHookEx(hHook)
hHook = SetWindowsHookEx(WH_KEYBOA
End Sub
End Class
Imports System.Runtime.InteropServ
Public Class HookHandlerClass
Public Shared hooked As Boolean
Public Shared kHook As Long = 0
Public Shared mHook As Long = 0
Public Const WH_KEYBOARD As Short = 2
Public Const KBH_MASK As Integer = &H20000000
Public Const HC_ACTION = 0
Public Const WM_RBUTTONDOWN = &H204
Public Const WH_MOUSE = 7
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Overloads Shared Function HookProc( _
ByVal nCode As Integer, _
ByVal wParam As Long, _
ByVal lParam As Long) As Integer
Dim buffer As String
MsgBox(nCode)
buffer = lParam.ToString()
MsgBox(buffer)
HookProc = CallNextHookEx(kHook, nCode, wParam, lParam)
End Function
End Class
How to hook the keyboard and mouse using VB .net. I am developing a COM application involving Microsoft Internet Explorer and I needed to trap the keys & mouse and selectively allow the user to be able to type certain moments and prevent him in certain moments. Can someone provide the skeletal structure for doing the same? At present I am using the following skeleton, but it is not able to hook.
Can someone please help.
Thanks in Advance
Arindam
Friend Class frmMain
Inherits System.Windows.Forms.Form
Public Shared hHook As Long = 0
Public Const WH_KEYBOARD As Short = 2
Public Const KBH_MASK As Integer = &H20000000
Public Const HC_ACTION = 0
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_LBUTTONUP = &H202
Public Const WM_RBUTTONDOWN = &H204
Public Const WH_MOUSE = 7
Public Delegate Function CallBack(ByVal nCode As Integer, ByVal wParam As Long, ByVal lParam As Long) As Integer
Public HookProc As CallBack
Public Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Integer, ByVal HookProc As CallBack, ByVal hInstance As Long, ByVal wParam As Integer) As Integer
Public Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer
Const EM_UNDO As Short = &HC7s
Private Declare Function OSWinHelp Lib "user32" Alias "WinHelpA" (ByVal hwnd As Integer, ByVal HelpFile As String, ByVal wCommand As Short, ByRef dwData As Integer) As Short
Private Sub frmMain_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
'Some Code
installHook()
End Sub
Public Sub installHook()
HookProc = New CallBack(AddressOf HookHandlerClass.HookProc)
UnhookWindowsHookEx(hHook)
hHook = SetWindowsHookEx(WH_KEYBOA
End Sub
End Class
Imports System.Runtime.InteropServ
Public Class HookHandlerClass
Public Shared hooked As Boolean
Public Shared kHook As Long = 0
Public Shared mHook As Long = 0
Public Const WH_KEYBOARD As Short = 2
Public Const KBH_MASK As Integer = &H20000000
Public Const HC_ACTION = 0
Public Const WM_RBUTTONDOWN = &H204
Public Const WH_MOUSE = 7
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Overloads Shared Function HookProc( _
ByVal nCode As Integer, _
ByVal wParam As Long, _
ByVal lParam As Long) As Integer
Dim buffer As String
MsgBox(nCode)
buffer = lParam.ToString()
MsgBox(buffer)
HookProc = CallNextHookEx(kHook, nCode, wParam, lParam)
End Function
End Class
ASKER
Thanks. The proposed solution looks to solve the issue but there is a new problem. I can't put any code block in the subroutine as it creates run time error after intercepting about 40 messages or so. I tried with writing down to a file instead of debug.writeline. It generates runtime error "System.NullReferenceExcep
So, I am not able to trap the messages and process them either.
Any help?
Thanks
Arindam
So, I am not able to trap the messages and process them either.
Any help?
Thanks
Arindam
I have tried MessageBox.Show(m.ToString
and it works fine. Are you getting error after intercepting 40 messages or always?
and it works fine. Are you getting error after intercepting 40 messages or always?
ASKER
I have gone through several articles on hooking and finally could find out that Windows limits a time frame to process a message. After, this time frame is over, it is giving the run time error. So, what is required is that I should somehow nullify hte message and send it for normal processing. I can't consume any message. This is what appears to me......
ASKER CERTIFIED SOLUTION
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ASKER
Please ignore the previous code fragment. The wrong fragment is posted and I am sorry for that
The fragment will be
Private Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As IntPtr
If (nCode < HC_ACTION) Then
Return CallNextHookEx(m_KeyboardH
ElseIf (nCode = HC_ACTION) Then
If wParam = WM_KEYDOWN Or wParam = WM_SYSKEYDOWN Then
P = CType(Marshal.PtrToStructu
P.scanCode = Nothing
P.vkCode = Nothing
Marshal.StructureToPtr(P, lParam, True)
Return lParam
End If
End Function
The fragment will be
Private Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As IntPtr
If (nCode < HC_ACTION) Then
Return CallNextHookEx(m_KeyboardH
ElseIf (nCode = HC_ACTION) Then
If wParam = WM_KEYDOWN Or wParam = WM_SYSKEYDOWN Then
P = CType(Marshal.PtrToStructu
P.scanCode = Nothing
P.vkCode = Nothing
Marshal.StructureToPtr(P, lParam, True)
Return lParam
End If
End Function
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
PAQ/Refund
Please leave any comments here within the next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
TheLearnedOne
EE Cleanup Volunteer
I will leave a recommendation in the Cleanup topic area that this question is:
PAQ/Refund
Please leave any comments here within the next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
TheLearnedOne
EE Cleanup Volunteer
right dropdown select WndProc. The new WndProc receives a Message object
as a parameter. Use its ToString method to display the message's name.
Call the base class's WndProc method to process the message normally. This
is very important! If you don't process the message normally, the form will
not be able to resize itself, draw its interior, and perform other standard
Windows functions.
Protected Overrides Sub WndProc(ByRef m As _
System.Windows.Forms.Messa
Debug.WriteLine(m.ToString
'here you can intercept the window message and do whatever you want witth it
MyBase.WndProc(m)
End Sub