KeyboardHook.cs

using System.Runtime.InteropServices;

namespace InputAutoSwitch
{
    /// <summary>
    /// 键盘钩子管理类
    /// </summary>
    public class KeyboardHook : IDisposable
    {
        private const int WH_KEYBOARD_LL = 13;
        private const int WM_KEYDOWN = 0x0100;
        private const int WM_KEYUP = 0x0101;
        private const int WM_SYSKEYDOWN = 0x0104;
        private const int WM_SYSKEYUP = 0x0105;

        private LowLevelKeyboardProc _proc;
        private IntPtr _hookID = IntPtr.Zero;
        private bool _isAutoSwitching = false; // 防止循环触发标志

        public event EventHandler? KeyPressed;

        public KeyboardHook()
        {
            _proc = HookCallback;
        }

        public void Start()
        {
            _hookID = SetHook(_proc);
        }

        public void Stop()
        {
            if (_hookID != IntPtr.Zero)
            {
                UnhookWindowsHookEx(_hookID);
                _hookID = IntPtr.Zero;
            }
        }

        public void SetAutoSwitchingFlag(bool value)
        {
            _isAutoSwitching = value;
        }

        private IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using (var curProcess = System.Diagnostics.Process.GetCurrentProcess())
            using (var curModule = curProcess.MainModule)
            {
                if (curModule != null && curModule.ModuleName != null)
                {
                    return SetWindowsHookEx(WH_KEYBOARD_LL, proc,
                        GetModuleHandle(curModule.ModuleName), 0);
                }
            }
            return IntPtr.Zero;
        }

        private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0)
            {
                // 捕获所有键盘按下事件 (按下和释放都算)
                int msg = wParam.ToInt32();
                if (msg == WM_KEYDOWN || msg == WM_KEYUP || msg == WM_SYSKEYDOWN || msg == WM_SYSKEYUP)
                {
                    // 如果是自动切换触发的按键,忽略它
                    if (!_isAutoSwitching)
                    {
                        KeyPressed?.Invoke(this, EventArgs.Empty);
                    }
                }
            }
            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }

        public void Dispose()
        {
            Stop();
        }

        // Win32 API 声明
        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool UnhookWindowsHookEx(IntPtr hhk);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string lpModuleName);
    }
}