Keyboard-Calculator/NumpadMonitor/KeyHandler.cs

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

namespace NumpadMonitor
{
    internal class KeyHandler
    {
        [DllImport("user32.dll")]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);

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

        public KeyInfo KeyInfo { get; private set; }
        private readonly IntPtr hWnd;
        private readonly int id;

        public void SetKeyCode(IntPtr keyCode)
        {
            KeyInfo.SetKeyCode(keyCode);
        }

        public KeyHandler(Keys key, Form form)
        {
            KeyInfo = new KeyInfo(key);
            hWnd = form.Handle;
            id = GetHashCode();
        }

        public KeyHandler(KeyInfo keyInfo, Form form)
        {
            KeyInfo = keyInfo;
            hWnd = form.Handle;
            id = GetHashCode();
        }

        public override int GetHashCode()
        {
            int hash = 17;
            hash = hash * 23 + KeyInfo.GetHashCode();
            hash = hash * 23 + hWnd.ToInt32();
            return hash;
        }

        public bool Register()
        {
            return RegisterHotKey(hWnd, id, KeyInfo.FsModifiers, (int)KeyInfo.Key);
        }

        public bool Unregiser()
        {
            return UnregisterHotKey(hWnd, id);
        }
    }
}