apewer-dotnet/Apewer.Windows/WinForm/HotKey.cs

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

namespace Apewer.WinForm
{

    /// <summary>热键。</summary>
    public sealed class HotKey : IMessageFilter
    {

        #region instance

        IntPtr _pointer = IntPtr.Zero;
        Keys _key = Keys.None;
        ModifierKey _modifier = ModifierKey.None;

        int _id = 0;
        Action<HotKey> _callback = null;

        /// <summary>热键的标识符。 </summary>
        public int Id { get => _id; }

        /// <summary>修饰键。</summary>
        public ModifierKey ModifierKey { get => _modifier; }

        /// <summary>按键。</summary>
        public Keys Key { get => _key; }

        private HotKey(IntPtr pointer, Keys key, ModifierKey modifier, Action<HotKey> callback)
        {
            if (callback == null) throw new ArgumentNullException(nameof(callback), "回调函数不能为空。");
            switch (key)
            {
                case Keys.KeyCode:
                case Keys.Modifiers:
                case Keys.None:
                case Keys.Shift:
                case Keys.Control:
                case Keys.Alt:
                    throw new ArgumentException($"按键【{key}】无法注册为热键。");
            }

            // 应用程序必须在0x0000到0xBFFF的范围内指定 ID 值。
            // 共享 DLL 必须通过 0xFFFF（GlobalAddAtom 函数返回的范围）指定0xC000区域中的值。
            _id = ((int)modifier << 16) & (int)key;

            _pointer = pointer;
            _callback = callback;
            _key = key;
            _modifier = modifier;
        }

        /// <summary></summary>
        public override string ToString()
        {
            var alt = (ModifierKey & ModifierKey.ALT) == ModifierKey.ALT ? "ALT + " : "";
            var ctrl = (ModifierKey & ModifierKey.CTRL) == ModifierKey.CTRL ? "CTRL + " : "";
            var shift = (ModifierKey & ModifierKey.SHIFT) == ModifierKey.SHIFT ? "SHIFT + " : "";
            var win = (ModifierKey & ModifierKey.WIN) == ModifierKey.WIN ? "WIN + " : "";
            var result = $"{alt}{ctrl}{shift}{win}{Key}";
            return result;
        }

        #endregion

        #region bind

        const int WM_HOTKEY = 0x0312;

        [DllImport("user32.dll")]
        static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, Keys vk);

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

        bool IMessageFilter.PreFilterMessage(ref Message m)
        {
            if (m.Msg == WM_HOTKEY && (int)m.WParam == _id)
            {
                _callback?.Invoke(this);
                return true;
            }
            return false;
        }

        void Bind()
        {
            var success = RegisterHotKey(_pointer, _id, (int)_modifier, _key);
            if (!success)
            {
                var error = Marshal.GetLastWin32Error();
                if (error == 1409) throw new Exception($"热键【{ToString()}】已被占用。");
                throw new Exception($"错误 {error}：注册热键【{ToString()}】失败。");
            }

            Application.AddMessageFilter(this);
        }

        /// <summary>释放热键。</summary>
        public void Release()
        {
            UnregisterHotKey(Application.OpenForms[0].Handle, _id);
        }

        #endregion

        // Virtual-Key 代码
        // https://learn.microsoft.com/zh-cn/windows/win32/inputdev/virtual-key-codes

        /// <summary>绑定热键。</summary>
        /// <param name="form">将接收热键生成的 WM_HOTKEY（0x0312）消息的窗口句柄。</param>
        /// <param name="key">热键的虚拟键代码。</param>
        /// <param name="modifier">修饰键。</param>
        /// <param name="callback">回调。</param>
        /// <exception cref="ArgumentNullException" />
        /// <exception cref="ArgumentException" />
        /// <exception cref="Exception" />
        public static HotKey Bind(Form form, Keys key, ModifierKey modifier, Action<HotKey> callback)
        {
            if (form == null) throw new ArgumentNullException(nameof(form));
            if (callback == null) throw new ArgumentNullException(nameof(callback));

            var hotkey = new HotKey(form.Handle, key, modifier, callback);
            hotkey.Bind();
            return hotkey;
        }

        /// <summary>绑定热键。</summary>
        /// <remarks>WM_HOTKEY 消息将发布到调用线程的消息队列，并且必须在消息循环中进行处理。</remarks>
        /// <param name="key">热键的虚拟键代码。</param>
        /// <param name="modifier">修饰键。</param>
        /// <param name="callback">回调。</param>
        /// <exception cref="ArgumentNullException" />
        /// <exception cref="ArgumentException" />
        /// <exception cref="Exception" />
        public static HotKey Bind(Keys key, ModifierKey modifier, Action<HotKey> callback)
        {
            if (callback == null) throw new ArgumentNullException(nameof(callback));

            var hotkey = new HotKey(IntPtr.Zero, key, modifier, callback);
            hotkey.Bind();
            return hotkey;
        }

    }

}