Keyboard-Calculator/NumpadMonitor/NumpadMonitor.cs

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace NumpadMonitor
{
    public partial class NumpadMonitorForm : Form
    {
        private readonly List<KeyHandler> keyHandlers = new List<KeyHandler>();

        public delegate void NotifyKeyPressEvent(NumpadMonitorForm sender, KeyInfo key);

        public event NotifyKeyPressEvent KeyPressEvent;

        private readonly bool AlternativeKeySet;

        internal NumpadMonitorForm(List<KeyInfo> keyinfo, bool alternativeKeyset = false, bool visible = false)
        {
            AlternativeKeySet = alternativeKeyset;
            InitializeComponent();
            Opacity = visible ? 100 : 0;
            AddAllKeyHandlers(keyinfo);
        }

        private void AddAllKeyHandlers(List<KeyInfo> keyinfo)
        {
            foreach (KeyInfo key in keyinfo)
            {
                AddKeyHandler(key);
            }
        }

        private void AddKeyHandler(KeyInfo key)
        {
            KeyHandler keyHandler = new KeyHandler(key, this);
            keyHandler.Register();
            keyHandlers.Add(keyHandler);
        }

        private void HandleHotkey(IntPtr LParam)
        {
            KeyHandler handler = keyHandlers.Find(x => x.KeyInfo.KeyCode.Equals(LParam));
            if (handler == null) return;
            KeyInfo pressedKey = AlternativeKeySet ? KeySet.AlternativeToNumpad(handler.KeyInfo) : handler.KeyInfo;
            KeyPressEvent?.Invoke(this, pressedKey);
            label1.Text = pressedKey.ToString();
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == Constants.WM_HOTKEY_MSG_ID)
                HandleHotkey(m.LParam);
            base.WndProc(ref m);
        }

        public void DisposeElements()
        {
            keyHandlers.ForEach(x => x.Unregiser());
        }
    }
}