WinForms Retrieve Keyboard State without Form/UserControl

Question

I'd like to retrieve the state of the Ctrl keys in a place where I don't have a form.

Normally to get a key state I'd use Control_KeyDown / KeyUp events. However, the code that needs to know whether Ctrl is pressed is outside any form. There is a form displayed, but the code is supposed not to depend on that form but finding the key state on its own.

Surely there is a way to do that, only I don't succeed to find it on google.

Note that although the code doesn't "have" a form available, its still a WinForms application, so maybe the framework provides some class/object for me to achieve that goal.

Background:

During the application startup phase, I want one step to behave differntly if the Ctrl key is being pressed in that moment. The startup phase displays a splash screen, but the code for the startup isn't aware of that. Instead it reports progress to a callback, and that callback updates the splash screen.

If I use the splash screen for fetching the KeyDown event, I make the startup code depend on that splash screen, which introduces a circular dependency. I want to keep the freedom to remove the splash screen and replace by something different.

Answer 1

I've done exactly that just recently:

    static class NativeMethods
    {
        public static bool IsControlKeyDown()
        {
            return (GetKeyState(VK_CONTROL) & KEY_PRESSED) != 0;
        }
        private const int KEY_PRESSED = 0x8000;
        private const int VK_CONTROL = 0x11;
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        static extern short GetKeyState(int key);
    }

To test the code, create a new Console Application and use the following main method:

    static void Main(string[] args)
    {
        for (int i = 0; i < 100; i++)
        {
            Console.WriteLine(NativeMethods.IsControlKeyDown());
            System.Threading.Thread.Sleep(100);
        }
    }

Answer 2

Can't you just catch the Ctrl being pressed on the form that is displayed, since it seems that this form is also a part of the appication, and relay the click to the "formless" part of the code using an event that the form can invoke?

I might misunderstand what you are after here, but it seems like an option at least.

Answer 3

You could use the static method on Control called ModifierKeys

Control.ModifierKeys on MSDN

eg:

if (Control.ModifierKeys == Keys.Control)
{
    //...
}