如何停止進一步處理 C# 中的全局熱鍵

Question

我正在嘗試創建一個對全局熱鍵做出反應的 C# 應用程序； ALT+H然后當我松開ALT鍵時。 這實際上工作得很好，但我的問題是，當我的應用程序完成了它應該對熱鍵執行的任何操作時，它應該阻止其他應用程序處理該熱鍵。 我從 StackOverflow 帖子中獲得了下面的大部分代碼，C# 應用程序中的全局鍵盤捕獲，但我在其他地方看到了return (IntPtr)1; 應該能夠停止對密鑰的進一步處理。

但是...當我在 Word 或 Wordpad 中並按ALT+H然后 Word 會顯示所有類型的菜單 - 我不希望它顯示，因為我只希望我的應用程序執行某些操作:-)

我很抱歉這段相當長的代碼，但我認為它很重要，因此您可以獲得完整的概述。 我使用return (IntPtr)1;地方只有 1 return (IntPtr)1; .

我的代碼：

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Windows.Input;
    
namespace MyNewProgram
{
    static class Program
    {
    
        // Enable hotkeys
        // https://stackoverflow.com/a/604417/2028935
        private const int WH_KEYBOARD_LL = 13;
        private const int WM_KEYDOWN = 0x0100;
        private const int WM_KEYUP = 0x0101;
        private const int WM_SYSKEYUP = 0x0105;
        private const int VK_SHIFT = 0x10;
        private const int VK_MENU = 0x12;
        private static LowLevelKeyboardProc _proc = HookCallback;
        private static IntPtr _hookID = IntPtr.Zero;

        // Other variables
        public static bool isAltPressedInThisApp = false;

        private static MainWindow MyMainWindow;

        // --------------------------------------------------------------------------------------

        [STAThread] // STAThreadAttribute indicates that the COM threading model for the application is single-threaded apartment, https://stackoverflow.com/a/1361048/2028935

        static void Main()
        {
            // Hook application to keyboard
            _hookID = SetHook(_proc);

            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            MyMainWindow = new MainWindow();
            Application.Run(MyMainWindow);

            // Unhook application from keyboard
            UnhookWindowsHookEx(_hookID);
        }

        // --------------------------------------------------------------------------------------
        // Required functions for globally hooking the keyboard

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern short GetKeyState(int keyCode);

        [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);

        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

        // --------------------------------------------------------------------------------------
        // Hook the keyboard - action

        private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
            // React on KEYDOWN
            if (nCode >= 0 && ((wParam == (IntPtr)WM_KEYDOWN) || (wParam == (IntPtr)WM_SYSKEYUP)))
            {
                int vkCode = Marshal.ReadInt32(lParam);

                // H
                if ((Keys)vkCode == Keys.H)
                {
                    isAltPressedInThisApp = true;

                    // Is ALT pressed down
                    if ((GetKeyState(VK_MENU) & 0x8000) != 0)
                    {
                        Console.WriteLine("ALT + H");
                        return (IntPtr)1; // do not allow others to hook this key combo
                    }
                }
            }

            // React on KEYUP
            if (nCode >= 0 && wParam == (IntPtr)WM_KEYUP)
            {
                int vkCode = Marshal.ReadInt32(lParam);

                // Is ALT not pressed down
                if ((Keys)vkCode == Keys.LMenu)
                {
                    Console.WriteLine("ALT UP");
                }
            }

            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }

        // --------------------------------------------------------------------------------------
        // Hook the keyboard

        private static IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using (Process curProcess = Process.GetCurrentProcess())
            using (ProcessModule curModule = curProcess.MainModule)
            {
                return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
            }
        }
    }
}

我不是一個可靠的 C# 開發人員，因為我在這里開始了我的前幾個小步 - 那么我為什么要把自己投入全局熱鍵的深水作為第一件事;-) 有沒有人可以在這里給出一些提示可能在某處有一個愚蠢的錯誤？

Answer 1

背后的想法是，每當按下 alt 鍵時，它就會開始將鍵吞入一個本地列表中。 如果我們需要看到的模式已經被看到，它就不會發送，但對於其他模式，它會按照收到的順序再次發送密鑰。

考試階段代碼：

    enum WM
    {
        WM_KEYDOWN = 0x0100,
        WM_KEYUP = 0x0101,
        WM_SYSKEYUP = 0x0105,
        WM_SYSKEYDOWN = 0x0104,
    }

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode < 0)
            return CallNextHookEx(_hookID, nCode, wParam, lParam);

        KBDLLHOOKSTRUCT kbd = (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(KBDLLHOOKSTRUCT));
        Enum.TryParse<Keys>($"{kbd.vkCode}", out Keys key);
        Enum.TryParse<WM>($"{wParam}", out WM message);

        Console.WriteLine($"{message}:{key}");

        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

當按下alt+h並釋放時，輸出：

WM_SYSKEYDOWN:LMenu
WM_SYSKEYDOWN:H
WM_SYSKEYUP:H
WM_KEYUP:LMenu

如您所見，Windows 發送了 alt 和 h 鍵。 您提供的代碼僅捕獲 H 鍵，因此接收鍵盤消息的窗口認為按下了 alt。

沒有人可以獲取和過濾掉以前按下的鍵，所以我們需要在看到 alt 鍵被按下時捕獲它。 如果下一個密鑰不是 H，我們應該按照我們收到的順序發送我們獲取的密鑰。

我寫了下面的代碼來處理這種情況，但我不能確定它在真正的 Windows 機器上是如何工作的，因為我有一個 osx 操作系統，因為我在虛擬機中運行 Windows，這也是更改密鑰當我按下時中風。

如果還不夠，你可以等一下，我也許可以在我的辦公室用真正的 Windows 機器嘗試解決這個問題。 但我認為你明白了這個想法並自己解決了。

    [StructLayout(LayoutKind.Sequential)]
    public class KBDLLHOOKSTRUCT
    {
        public uint vkCode;
        public uint scanCode;
        public KBDLLHOOKSTRUCTFlags flags;
        public uint time;
        public UIntPtr dwExtraInfo;
    }

    [Flags]
    public enum KBDLLHOOKSTRUCTFlags : uint
    {
        LLKHF_EXTENDED = 0x01,
        LLKHF_INJECTED = 0x10,
        LLKHF_ALTDOWN = 0x20,
        LLKHF_UP = 0x80,
    }
    [DllImport("user32.dll")]
    static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, UIntPtr dwExtraInfo);

    enum WM
    {
        WM_KEYDOWN = 0x0100,
        WM_KEYUP = 0x0101,
        WM_SYSKEYUP = 0x0105,
        WM_SYSKEYDOWN = 0x0104,
    }

    private static void ReSendKeys(int index = -1)
    {
        _index = -1;

        var copiedKeys = _swallowedKeys.ToArray();
        for (int i = 0; i < copiedKeys.Length; ++i)
        {
            bool up = copiedKeys[i].Item1 == (IntPtr)WM.WM_SYSKEYUP || copiedKeys[i].Item1 == (IntPtr)WM.WM_KEYUP;
            keybd_event((byte)copiedKeys[i].Item2.vkCode, (byte)copiedKeys[i].Item2.scanCode, up ? 2u : 0u, UIntPtr.Zero);
        }

        _index = index;
        _swallowedKeys.Clear();
    }

    private static List<Tuple<IntPtr, KBDLLHOOKSTRUCT>> _swallowedKeys = new List<Tuple<IntPtr, KBDLLHOOKSTRUCT>>();

    private static int _index = 0;
    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode < 0)
            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        
        KBDLLHOOKSTRUCT kbd = (KBDLLHOOKSTRUCT)Marshal.PtrToStructure(lParam, typeof(KBDLLHOOKSTRUCT));
        Enum.TryParse<Keys>($"{kbd.vkCode}", out Keys key);
        Enum.TryParse<WM>($"{wParam}", out WM message);

        Console.Write($"{message}:{key}");

        // we know that when _index is -1, ReSendKeys function has been called
        // so do not filter out first alt key
        if (_index == -1)
        {
            _index++;
            Console.WriteLine();
            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }

        // we are at the beginning of the sequence we will catch
        // if it's alt key filter it out, and increment the variable
        if (_index == 0)
        {
            _swallowedKeys.Add(new Tuple<IntPtr, KBDLLHOOKSTRUCT>(wParam, kbd));

            if (message == WM.WM_SYSKEYDOWN && key == Keys.LMenu)
            {
                _index++;

                Console.WriteLine(" filtered out");
                return (IntPtr)1;
            }
            else
            {
                _swallowedKeys.Clear();
                // do nothing
            }
        }

        if (_index == 1)
        {
            _swallowedKeys.Add(new Tuple<IntPtr, KBDLLHOOKSTRUCT>(wParam, kbd));

            // if the next key is H, then filter it out also
            if (message == WM.WM_SYSKEYDOWN && key == Keys.H)
            {
                _index++;
                _swallowedKeys.RemoveAt(_swallowedKeys.Count - 1);

                Console.WriteLine(" filtered out");
                return (IntPtr)1;
            }
            // if not, we filtered out wrong sequence, we need to resend them
            else
            {
                Console.WriteLine();
                ReSendKeys();
                return (IntPtr)1;
            }
        }

        if (_index == 2)
        {
            _swallowedKeys.Add(new Tuple<IntPtr, KBDLLHOOKSTRUCT>(wParam, kbd));

            if (message == WM.WM_SYSKEYUP && key == Keys.H)
            {
                _index++;
                _swallowedKeys.RemoveAt(_swallowedKeys.Count - 1);

                Console.WriteLine(" filtered out");
                return (IntPtr)1;
            }
            else
            {
                // if user pressed H but not released and pressed another key at the same time
                // i will pass that situation, if u need to handle something like that, you got the idea, please fill that block of code
            }
        }

        if (_index == 3)
        {
            _swallowedKeys.Add(new Tuple<IntPtr, KBDLLHOOKSTRUCT>(wParam, kbd));

            if (message == WM.WM_KEYUP && key == Keys.LMenu)
            {
                _index = 0;
                _swallowedKeys.Clear();

                Console.WriteLine(" filtered out");
                Console.WriteLine("shortcut disabled");
                return (IntPtr)1;
            }
            else
            {
                Console.WriteLine();
                // user has been pressed Alt + H, H released but not alt, so we can expect one H again, but we need to send this pressed key with Alt prefixed
                ReSendKeys(1);
                return (IntPtr)1;
            }
        }

        Console.WriteLine();
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }