flopoloco's picture

OpenTK Keyboard Input Example

3 different ways of getting key input, each with his benefits.

using System;
using OpenTK;
using OpenTK.Input;
namespace OpenTKKey
	class MainClass : GameWindow
		// 1. Exit using keyboard event handler
		// 2. Exit by using method of OpenTK GameWindow
		// 3. By using the Keyboard property
		protected override void OnLoad (EventArgs e)
			// 1
			Keyboard.KeyDown += HandleKeyDown;
		// 1
		void HandleKeyDown (object sender, KeyboardKeyEventArgs e)
			if (e.Key == Key.Escape) Exit ();
		// 2
		protected override void OnKeyPress (OpenTK.KeyPressEventArgs e)
			// This brings this Exact string "Escape"
			// If you don not want to use Windows.Forms assembly then
			// check against plain charachters else you do it like this
			// for type value safety: System.Windows.Forms.Keys.Q
			if (e.KeyChar == 'q' || e.KeyChar == 'Q')
				Exit ();
		// 3
		protected override void OnUpdateFrame (FrameEventArgs e)
			if (Keyboard[Key.Space])
				Exit ();
			base.OnUpdateFrame (e);
		public static void Main (string[] args)
			using (var m = new MainClass()) {
				m.Run ();


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flopoloco's picture

I am searching how to get the Keyboard device without the GameWindow.
Must be a keyboard instantiation with event handler... Any ideas?

rvIceBreaker's picture

Getting Input while bypassing the 'GameWindow' requires a couple of things...

Firstly, to get input in general, you need to have the respective 'Device' class, so you'll need something like this...

MouseDevice mouse; //Mouse Device ( for mouse input )
KeyboardDevice keyboard; //Keyboard Device ( for keyboard input )

In order to instantiate this class, you have to have access to the 'IInputDriver' from the NativeWindow your project is using. I made a singleton reference to my NativeWindow and grabbed the IInputDriver when i needed it.

NativeWindow nativeWindow = new NativeWindow( ... );
IInputDriver inputDriver = nativeWindow.InputDriver;
MouseDevice mouse = inputDriver.Mouse[0]; //'inputDriver.Mouse' is a collection of available MouseDevice classes; we want the first device
KeyboardDevice keyboard = inputDriver.Keyboard[0]; //'inputDriver.Keyboard' is a collection of available KeyboardDevice classes; we want the first device

After you have all of this, you can add new EventHandlers to the ButtonUp/Down and KeyUp/Down events.

mouse.ButtonDown += new EventHandler<MouseButtonEventArgs>(mouse_ButtonDown);
mouse.ButtonUp += new EventHandler<MouseButtonEventArgs>(mouse_ButtonUp);
keyboard.KeyDown += new EventHandler<KeyboardKeyEventArgs>(keyboard_KeyDown);
keyboard.KeyUp += new EventHandler<KeyboardKeyEventArgs>(keyboard_KeyUp);

You can also access things like the mouse position and the wheel position from the MouseDevice class.

The main thing to keep in mind is that you'll need to keep a reference to your NativeWindow instance for many reasons (depending on your desired features), so be sure to do so to save yourself a headache.