Add global hotkey support

MouseTrap/src/MouseTrapTrayIcon.cs

@@ -1,4 +1,4 @@
-using MouseTrap.Forms;
+using MouseTrap.Forms;
 using MouseTrap.Models;
 using MouseTrap.Service;
 
@@ -10,6 +10,8 @@ public class MouseTrapTrayIcon : TrayIcon {
     private WeakReference<ConfigFrom>? _configFromRef;
 
 
+    private GlobalHotkeyManager? _hotkeys;
+    private Form? _hotkeyForm;
     public MouseTrapTrayIcon(ServiceThread service)
     {
         _service = service;
@@ -33,6 +35,20 @@ public MouseTrapTrayIcon(ServiceThread service)
         ContextMenu.Items[0].Font = WithFontStyle(ContextMenu.Items[0].Font, FontStyle.Bold);
 
         Visible = true;
+        // initialize hotkeys using a minimal form
+        _hotkeyForm = new Form { ShowInTaskbar = false, WindowState = FormWindowState.Minimized, Opacity = 0 };
+        _hotkeyForm.Load += (s, e) => _hotkeyForm.Hide();
+        _hotkeyForm.Show();
+        _hotkeys = new GlobalHotkeyManager(_hotkeyForm.Handle);
+        _hotkeys.EnableRequested += () => {
+            _service.StartService();
+            ((ToolStripMenuItem)ContextMenu.Items[1]).Checked = true;
+        };
+        _hotkeys.DisableRequested += () => {
+            _service.StopService();
+            ((ToolStripMenuItem)ContextMenu.Items[1]).Checked = false;
+        };
+        _hotkeys.Register();
 
         // show config form on first startup
         var settings = Settings.Load();
@@ -77,6 +93,7 @@ protected override void WndProc(ref Message m)
             Close();
         }
 
+        _hotkeys?.HandleWndProc(ref m);
         _service.WndProc(ref m);
 
         base.WndProc(ref m);
@@ -90,4 +107,14 @@ private static Font WithFontStyle(Font font, FontStyle style)
     {
         return new Font(font.Name, font.Size, style, font.Unit);
     }
+    protected override void Dispose(bool disposing)
+    {
+        if (disposing)
+        {
+            _hotkeys?.Unregister();
+            _hotkeys?.Dispose();
+            _hotkeyForm?.Dispose();
+        }
+        base.Dispose(disposing);
+    }
 }

MouseTrap/src/Service/GlobalHotkeyManager.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Windows.Forms;
+
+namespace MouseTrap.Service;
+
+public sealed class GlobalHotkeyManager : IDisposable
+{
+    private const int WM_HOTKEY = 0x0312;
+
+    private const int HOTKEY_ENABLE  = 1;
+    private const int HOTKEY_DISABLE = 2;
+
+    private const uint MOD_WIN = 0x0008;
+
+    private readonly IntPtr _windowHandle;
+    private bool _registered;
+
+    public event Action? EnableRequested;
+    public event Action? DisableRequested;
+
+    public GlobalHotkeyManager(IntPtr windowHandle)
+    {
+        _windowHandle = windowHandle;
+    }
+
+    public void Register()
+    {
+        if (_registered)
+            return;
+
+        // Win + PageUp
+        RegisterHotKey(_windowHandle, HOTKEY_ENABLE, MOD_WIN, (uint)Keys.PageUp);
+
+        // Win + PageDown
+        RegisterHotKey(_windowHandle, HOTKEY_DISABLE, MOD_WIN, (uint)Keys.PageDown);
+
+        _registered = true;
+    }
+
+    public void Unregister()
+    {
+        if (!_registered)
+            return;
+
+        UnregisterHotKey(_windowHandle, HOTKEY_ENABLE);
+        UnregisterHotKey(_windowHandle, HOTKEY_DISABLE);
+
+        _registered = false;
+    }
+
+    public void HandleWndProc(ref Message m)
+    {
+        if (m.Msg != WM_HOTKEY)
+            return;
+
+        switch ((int)m.WParam)
+        {
+            case HOTKEY_ENABLE:
+                EnableRequested?.Invoke();
+                break;
+
+            case HOTKEY_DISABLE:
+                DisableRequested?.Invoke();
+                break;
+        }
+    }
+
+    public void Dispose()
+    {
+        Unregister();
+    }
+
+    #region Win32
+
+    [DllImport("user32.dll")]
+    private static extern bool RegisterHotKey(
+        IntPtr hWnd,
+        int id,
+        uint fsModifiers,
+        uint vk
+    );
+
+    [DllImport("user32.dll")]
+    private static extern bool UnregisterHotKey(
+        IntPtr hWnd,
+        int id
+    );
+
+    #endregion
+}