Allowing Global Hotkeys

Question

First of all, I am not a true coder however I am happy with what I have done thus far.

I have written this code below which is to do with robotics. The code below allows me to user keyboard shortcuts when you click on the form. However, I need the hotkeys to work whether the application is or is not in focus or even minimized.

I have looked already online but it is not very clear.

Public Class MainForm

    Private Sub MainForm_KeyDown(sender As Object, e As KeyEventArgs) Handles Me.KeyDown

        If (e.KeyCode And Not Keys.Modifiers) = Keys.T AndAlso e.Modifiers = Keys.Control Then
            DF1Com1.Write("O:1/0", "1")  ' (O:9/0) (R)  
        End If

        'If e.KeyCode = Keys.R Then
        'DF1Com1.Write("O:1/0", "1")  ' (O:9/0) (R)   
        'End If

    End Sub

    Private Sub MainForm_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp

        If (e.KeyCode And Not Keys.Modifiers) = Keys.T AndAlso e.Modifiers = Keys.Control Then
            DF1Com1.Write("O:1/0", "0")  ' (O:9/0) (R) 
        End If

        'If e.KeyCode = Keys.R Then
        'DF1Com1.Write("O:1/0", "0") ' (O:9/0) (R) 
        'End If

    End Sub

Public Class MainForm


    Private Sub MainForm_KeyDown(sender As Object, e As KeyEventArgs) Handles Me.KeyDown

        If (e.KeyCode And Not Keys.Modifiers) = Keys.T AndAlso e.Modifiers = Keys.Control Then
            DF1Com1.Write("O:1/0", "1")  ' (O:9/0) (R) 
        End If

        'If e.KeyCode = Keys.R Then
        'DF1Com1.Write("O:1/0", "1")  ' (O:9/0) (R)
        'End If

    End Sub

    Private Sub MainForm_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp

        If (e.KeyCode And Not Keys.Modifiers) = Keys.T AndAlso e.Modifiers = Keys.Control Then
            DF1Com1.Write("O:1/0", "0")  ' (O:9/0) (R)  
        End If

        'If e.KeyCode = Keys.R Then
        'DF1Com1.Write("O:1/0", "0") ' (O:9/0) (R) 
        'End If

    End Sub

End Class

Update:

Right. I have added a class now which allow GlobalKey to be registered.

In my main form I now have this key:

   Public Class MainForm
    Dim hkr As New HotKeyRegistryClass(Me.Handle)

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.A).ToString()
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.S).ToString()
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.D).ToString()
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.F).ToString()
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.G).ToString()
        hkr.Register(HotKeyRegistryClass.Modifiers.MOD_SHIFT Or HotKeyRegistryClass.Modifiers.MOD_CTRL, Keys.H).ToString()
    End Sub

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = HotKeyRegistryClass.Messages.WM_HOTKEY Then 'NOT THE ACTUAL WINDOWS NAMESPACE
            Dim ID As String = m.WParam.ToString()
            Select Case ID
                Case 0 : If DF1Com1.Write("O:1/0", "1") Then DF1Com1.Write("O:1/0", "0")
                Case 1 : MessageBox.Show("S")
                Case 2 : MessageBox.Show("D")
                Case 3 : MessageBox.Show("F")
                Case 4 : MessageBox.Show("G")
                Case 5 : MessageBox.Show("H")
            End Select
        End If
        MyBase.WndProc(m)
    End Sub

If you have a look at Case 0. It works however it does not put the key back up. It leaves it pressed down all the time. I need it when the key is depressed it 'DF1Com1.Write("O:1/0", "0")'

Class Code

Public NotInheritable Class HotKeyRegistryClass
    Private Declare Function RegisterHotKey Lib "user32.dll" (ByVal handle As IntPtr, ByVal id As Int32, ByVal fsModifier As Int32, ByVal vk As Int32) As Int32
    Private Declare Function UnregisterHotKey Lib "user32.dll" (ByVal handle As IntPtr, ByVal id As Int32) As Int32
    Private Handle As IntPtr = IntPtr.Zero
    Private Registry As New System.Collections.Generic.List(Of Int32)
    Public Enum Messages
        [WM_HOTKEY] = &H312
    End Enum
    Public Enum Modifiers
        [MOD_ALT] = &H1
        [MOD_CTRL] = &H2
        [MOD_SHIFT] = &H4
    End Enum
    Sub New(ByVal Handle As IntPtr)
        Me.Handle = Handle
    End Sub
    Public Function Register(ByVal Modifier As Int32, ByVal Key As System.Windows.Forms.Keys) As Int32
        Dim ret As Int32
        ret = NextAvailableIndex()
        Call RegisterHotKey(Me.Handle, ret, Modifier, Key)
        Registry.Insert(ret, ret)
        Return ret
    End Function
    Public Sub Unregister(ByVal ID As Int32)
        Call UnregisterHotKey(Me.Handle, ID)
        Registry.Remove(ID)
    End Sub
    Private Function NextAvailableIndex() As Int32
        Dim ret As Int32 = 0
        Dim n As Int32 = 0
        For i As Int32 = 0 To Registry.Count - 1
            If Registry(i) = n Then
                n = n + 1
            ElseIf n < Registry(i) Then
                Return n
            End If
        Next
        If n = Registry.Count Then
            Return Registry.Count
        End If
        Return ret
    End Function
End Class

Answer 1

Another option for accomplishing this could be to use boolean to keep track. Doing this means, press the hotkey to start then press again to stop.

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
Static toggle As Boolean
        If m.Msg = HotKeyRegistryClass.Messages.WM_HOTKEY Then 'NOT THE ACTUAL WINDOWS NAMESPACE
            Dim ID As String = m.WParam.ToString()
            Select Case ID
                Case 0 :
            If toggle Then
             DF1Com1.Write("O:1/0", "0")
            Else
                        DF1Com1.Write("O:1/0", "1")
            End If
            toggle = Not toggle
                Case 1 : MessageBox.Show("S")
                Case 2 : MessageBox.Show("D")
                Case 3 : MessageBox.Show("F")
                Case 4 : MessageBox.Show("G")
                Case 5 : MessageBox.Show("H")
            End Select
        End If
        MyBase.WndProc(m)
    End Sub

Answer 2

Unfortunately, RegisterHotkey only tells you when a key combination has been activated. Also, as you already realize, the KeyDown and KeyUp events you have will only work when your app has focus.

The only way you can get truly global KeyDown and KeyUp is by using a low level keyboard hook. Since I don't want to copy my entire answer I will simply link to it. The link will provide you some direction in setting up a keyboard hook.

How to disable/override Windows 10 Hotkeys with C#

Another possibility is to execute both commands on the hotkey activation like this...

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = HotKeyRegistryClass.Messages.WM_HOTKEY Then 'NOT THE ACTUAL WINDOWS NAMESPACE
            Dim ID As String = m.WParam.ToString()
            Select Case ID
                Case 0 : 
                    DF1Com1.Write("O:1/0", "1")
                    System.Threading.Thread.Sleep(2000)
                    DF1Com1.Write("O:1/0", "0")
                Case 1 : MessageBox.Show("S")
                Case 2 : MessageBox.Show("D")
                Case 3 : MessageBox.Show("F")
                Case 4 : MessageBox.Show("G")
                Case 5 : MessageBox.Show("H")
            End Select
        End If
        MyBase.WndProc(m)
    End Sub