How to listen keyboard in background and fire keystrokes on demand?

Question

I want to make a program in vb.NET 2008 which will listen keyboard in background, i.e. even though the application is minimized (globally). If a specific key is been pressed

Answer 1

If you use KeyboardHook class, make sure you have to build your program before using. With regards to the question for a specific key, you can trigger it in KeyDown or KeyUp event. But before that, you have to use sendkeys to send keys to active window.

SendKeys.Send("L") 'Sends letter L to active window.

Then you can do the following code; below checks if letter "a" is being pressed.

Private Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
    Debug.WriteLine(Key.ToString) 
    if Key.ToString() = "a" then
     'trigger your sendkeys
    end if
End Sub 

To trigger a specific key like a switch button, just declare a boolean variable to check if the button is switched or not. You can declare it globally:

Dim switch as boolean = false

Just update the area where you set a condition to check the letter pressed. It will look like below:

if Key.ToString() = "a" then
  if switch = false then
    switch = true
    'trigger send keys
  else
    switch = false
    'deactivate send keys
  end if
end if

To have a specific time in sending keys, use timer. I hope it helps.