HotKeyInternals.cs

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace CustomGlobalHotkeys {
	public class HotKeyInternals {
		public static event EventHandler < HotKeyEventArgs > HotKeyPressed;

		public static int InternalRegisterHotKey(Keys keys) {
			int id = System.Threading.Interlocked.Increment(ref _id);

			KeyModifiers modifiers = 0;

			if ((keys & Keys.Shift) != Keys.None) modifiers |= KeyModifiers.Shift;
			if ((keys & Keys.Alt) != Keys.None) modifiers |= KeyModifiers.Alt;
			if ((keys & Keys.Control) != Keys.None) modifiers |= KeyModifiers.Control;

			if (RegisterHotKey(_wnd.Handle, id, (uint) modifiers, (uint)(keys & Keys.KeyCode))) return id;
			else return - 1000;
		}

		public static bool InternalUnregisterHotKey(int id) {
			return UnregisterHotKey(_wnd.Handle, id);
		}

		protected static void OnHotKeyPressed(HotKeyEventArgs e) {
			if (HotKeyInternals.HotKeyPressed != null) {
				HotKeyInternals.HotKeyPressed(null, e);
			}
		}

		private static MessageWindow _wnd = new MessageWindow();

		private class MessageWindow: NativeWindow,
		IDisposable {
			public MessageWindow() {
				CreateHandle(new CreateParams());
			}

			public void Dispose() {
				DestroyHandle();
			}

			protected override void WndProc(ref Message m) {
				if (m.Msg == WM_HOTKEY) {
					HotKeyEventArgs e = new HotKeyEventArgs(m.LParam);
					HotKeyInternals.OnHotKeyPressed(e);
				}

				base.WndProc(ref m);
			}

			private const int WM_HOTKEY = 0x312;
		}

		[DllImport("user32")]
		private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

		[DllImport("user32")]
		private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

		private static int _id = 0;
	}

	public class HotKeyEventArgs: EventArgs {
		public readonly Keys Key;
		public readonly KeyModifiers Modifiers;

		public HotKeyEventArgs(Keys key, KeyModifiers modifiers) {
			this.Key = key;
			this.Modifiers = modifiers;
		}

		public HotKeyEventArgs(IntPtr hotKeyParam) {
			uint param = (uint) hotKeyParam.ToInt64();
			Key = (Keys)((param & 0xffff0000) >> 16);
			Modifiers = (KeyModifiers)(param & 0x0000ffff);
		}
	}

	[Flags]
	public enum KeyModifiers {
		Alt = 1,
		Control = 2,
		Shift = 4,
		Windows = 8,
		NoRepeat = 0x4000
	}
}