VB.NET - Making this application return two integers to set up mouse hook

Question

I've managed to get this C# code (not my own!) working in VB.NET, to implement a mouse hook in a Console application. Here's the VB.NET code:

Imports System.Runtime.InteropServices
Imports System.Windows.Forms

Module Module1
Class InterceptMouse
    Private Shared _proc As LowLevelMouseProc = AddressOf HookCallback
    Private Shared _hookID As IntPtr = IntPtr.Zero

    Public Shared Sub Main()
        _hookID = SetHook(_proc)
        Application.Run()
        UnhookWindowsHookEx(_hookID)
    End Sub

    Private Shared Function SetHook(proc As LowLevelMouseProc) As IntPtr
        Using curProcess As Process = Process.GetCurrentProcess()
            Using curModule As ProcessModule = curProcess.MainModule
                Return SetWindowsHookEx(WH_MOUSE_LL, proc, GetModuleHandle(curModule.ModuleName), 0)
            End Using
        End Using
    End Function

    Private Delegate Function LowLevelMouseProc(nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr

    Private Shared Function HookCallback(nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr
        Dim MouseSetting As Integer = MouseMessages.WM_LBUTTONDOWN
        Dim hookStruct As MSLLHOOKSTRUCT
        If nCode >= 0 AndAlso MouseSetting = CType(wParam, MouseMessages) Then
            hookStruct = CType(Marshal.PtrToStructure(lParam, GetType(MSLLHOOKSTRUCT)), MSLLHOOKSTRUCT)
            Console.WriteLine(hookStruct.pt.x & ", " & hookStruct.pt.y)
        End If
        Dim pt As New POINT
        pt.x = hookStruct.pt.x
        pt.y = hookStruct.pt.y
        MouseCoordinates.Add(pt)
        Return CallNextHookEx(_hookID, nCode, wParam, lParam)

    End Function

    Private Const WH_MOUSE_LL As Integer = 14

    Private Enum MouseMessages
        WM_LBUTTONDOWN = &H201
        WM_LBUTTONUP = &H202
        WM_MOUSEMOVE = &H200
        WM_MOUSEWHEEL = &H20A
        WM_RBUTTONDOWN = &H204
        WM_RBUTTONUP = &H205
    End Enum

    <StructLayout(LayoutKind.Sequential)> _
    Public Structure POINT
        Public x As Integer
        Public y As Integer
    End Structure

    <StructLayout(LayoutKind.Sequential)> _
    Private Structure MSLLHOOKSTRUCT
        Public pt As POINT
        Public mouseData As UInteger
        Public flags As UInteger
        Public time As UInteger
        Public dwExtraInfo As IntPtr
    End Structure

    <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
    Private Shared Function SetWindowsHookEx(idHook As Integer, lpfn As LowLevelMouseProc, hMod As IntPtr, dwThreadId As UInteger) As IntPtr
    End Function

    <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
    Private Shared Function UnhookWindowsHookEx(hhk As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
    End Function

    <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
    Private Shared Function CallNextHookEx(hhk As IntPtr, nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr
    End Function

    <DllImport("kernel32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
    Private Shared Function GetModuleHandle(lpModuleName As String) As IntPtr
    End Function
End Class

I've then called it from the Sub Main:

Sub Main()
    InterceptMouse.Main()
End Sub

However, when I debug it, it goes to the Application.Run() line and it doesn't advance to the next line, so I can't see what it's doing behind-the-scenes. It then waits for user input and returns integer coordinates on the Console. This isn't what I want it to do. I want to have this code running in another function or a Background Worker, passing coordinates to the main thread whenever it receives a mouse-click, so that it can handle the rest. The problem is, this code is far too complex for my level of understanding and I don't really know how it works. If I can at least manage to make the Console return mouse coordinates whenever the user clicks, I should be able to ignore it and handle the rest of the code from there.

Is there a good reason you are using a console, when you could use something like winforms with this built in? — Steve, Nov 18 '13 at 21:38
A good reason? Heck no. I want to make a Console User Interface designer for my Computing Project, and that would be so much easier if I could successfully implement a mouse hook. — Lou, Nov 18 '13 at 21:46
Application.Run isn't your own class, right? It's the System.Windows.Forms Application class, right? In that case, your calling into a windows message loop which waits for windows GUI input. Replace the "Application.Run" with your code (e.g. "Console.ReadLine") set a breakpoint in the mouse hook and try again. — Roman Gruber, Nov 18 '13 at 23:38

score 3 · Accepted Answer · answered Nov 19 '13 at 03:20

A good reason? Heck no.

I like the way you throw caution to the wind. Use at your own peril!

Not sure exactly how you're going to use this within your Console application...

...I've refactored it just a bit:

Imports System.Windows.Forms
Imports System.Runtime.InteropServices
Module Module1

    Private counter As Integer = 0
    Private WithEvents IM As InterceptMouse

    Sub Main()
        IM = InterceptMouse.Instance
        IM.Start()

        While counter < 3
            System.Threading.Thread.Sleep(100)
        End While

        IM.Shutdown()

        Console.Write("Press Enter to Quit")
        Console.ReadLine()
    End Sub

    Private Sub IM_MouseClick(pt As InterceptMouse.POINT) Handles IM.MouseClick
        Console.WriteLine(pt.x.ToString() & ", " & pt.y.ToString())
        counter = counter + 1
    End Sub

    Public Class InterceptMouse
        Inherits ApplicationContext

        Public Event MouseClick(ByVal pt As InterceptMouse.POINT)

        Private Shared _IM As InterceptMouse
        Public Shared ReadOnly Property Instance() As InterceptMouse
            Get
                If IsNothing(_IM) Then
                    _IM = New InterceptMouse()
                End If
                Return _IM
            End Get
        End Property

        Private _proc As LowLevelMouseProc = AddressOf HookCallback
        Private _hookID As IntPtr = IntPtr.Zero
        Private T As System.Threading.Thread = Nothing

        Private Sub New()
        End Sub

        Public Sub Start()
            If IsNothing(T) Then
                T = New Threading.Thread(AddressOf Main)
                T.Start()
            End If
        End Sub

        Private Sub Main()
            _hookID = SetHook(_proc)
            Application.Run(Me)
            UnhookWindowsHookEx(_hookID)
            T = Nothing
        End Sub

        Public Sub Shutdown()
            If Not IsNothing(T) Then
                Application.Exit()
            End If
        End Sub

        Private Function SetHook(proc As LowLevelMouseProc) As IntPtr
            Using curProcess As Process = Process.GetCurrentProcess()
                Using curModule As ProcessModule = curProcess.MainModule
                    Return SetWindowsHookEx(WH_MOUSE_LL, proc, GetModuleHandle(curModule.ModuleName), 0)
                End Using
            End Using
        End Function

        Private Delegate Function LowLevelMouseProc(nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr

        Private Function HookCallback(nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr
            Dim MouseSetting As Integer = MouseMessages.WM_LBUTTONDOWN
            Dim hookStruct As MSLLHOOKSTRUCT
            If nCode >= 0 AndAlso MouseSetting = CType(wParam, MouseMessages) Then
                hookStruct = CType(Marshal.PtrToStructure(lParam, GetType(MSLLHOOKSTRUCT)), MSLLHOOKSTRUCT)
                Dim pt As New POINT
                pt.x = hookStruct.pt.x
                pt.y = hookStruct.pt.y
                RaiseEvent MouseClick(pt)
            End If
            Return CallNextHookEx(_hookID, nCode, wParam, lParam)
        End Function

        Private Const WH_MOUSE_LL As Integer = 14

        Private Enum MouseMessages
            WM_LBUTTONDOWN = &H201
            WM_LBUTTONUP = &H202
            WM_MOUSEMOVE = &H200
            WM_MOUSEWHEEL = &H20A
            WM_RBUTTONDOWN = &H204
            WM_RBUTTONUP = &H205
        End Enum

        <StructLayout(LayoutKind.Sequential)> _
        Public Structure POINT
            Public x As Integer
            Public y As Integer
        End Structure

        <StructLayout(LayoutKind.Sequential)> _
        Private Structure MSLLHOOKSTRUCT
            Public pt As POINT
            Public mouseData As UInteger
            Public flags As UInteger
            Public time As UInteger
            Public dwExtraInfo As IntPtr
        End Structure

        <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
        Private Shared Function SetWindowsHookEx(idHook As Integer, lpfn As LowLevelMouseProc, hMod As IntPtr, dwThreadId As UInteger) As IntPtr
        End Function

        <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
        Public Shared Function UnhookWindowsHookEx(hhk As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
        End Function

        <DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
        Private Shared Function CallNextHookEx(hhk As IntPtr, nCode As Integer, wParam As IntPtr, lParam As IntPtr) As IntPtr
        End Function

        <DllImport("kernel32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
        Private Shared Function GetModuleHandle(lpModuleName As String) As IntPtr
        End Function

    End Class

End Module

Fantastic. I've not explored it fully but it's completely functional in the Console application :). Mind if I PM you if there are any problems? — Lou, Nov 19 '13 at 07:16

VB.NET - Making this application return two integers to set up mouse hook

1 Answers1