如何在C＃中制作全局键盘钩子

Question

如何在C＃中为Electron.NET应用制作全局键盘挂钩？我相信，只要它可以在控制台应用程序中运行，就应该可以在Electron.Net应用程序中正常运行。

我为这个问题提供了“解决方案”，但是它往往会占用大量CPU（7-10％）。如果没有其他选择，也许有人可以以某种方式使其真正有效：

using System;
using System.Runtime.InteropServices;
using System.Threading;

[DllImport("User32.dll")]
public static extern short GetAsyncKeyState(int vKey);

// Other VKey codes: https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes
public enum VKeys {
    LBUTTON = 0x01,     // Left mouse button
    RBUTTON = 0x02,     // Right mouse button
    KEY_0 = 0x30,       // 0 key
    KEY_1 = 0x31,       // 1 key
    KEY_2 = 0x32,       // 2 key
    KEY_3 = 0x33,       // 3 key
    KEY_4 = 0x34,       // 4 key
    KEY_5 = 0x35,       // 5 key
    KEY_6 = 0x36,       // 6 key
    KEY_7 = 0x37,       // 7 key
    KEY_8 = 0x38,       // 8 key
    KEY_9 = 0x39        // 9 key
}

public void Start()
{
    Thread HookThread = new Thread(delegate ()
    {
        var keys = Enum.GetValues(typeof(VKeys));

        while (true)
        {
            foreach (int key in keys)
            {
                var ks = GetAsyncKeyState(key);

                if (ks < 0)
                {
                    Console.WriteLine($"pressed {key}");
                    //Thread.Sleep(100);
                }

                //Thread.Sleep(1); // Even sleeping for '1ms' will delay it too much
            }
        }
    });

    HookThread.Start();
}

我发现的很多东西只有在使用WinForms或WPF时才有效。

编辑：

[我尝试了hanabanashiku的this答案，以及我在网上找到的许多其他答案，但是它们似乎都落后于键盘输入，并且似乎永远不会调用它们的回调函数。

我决定用C ++编写键盘钩子，编译为DLL，然后在我的C＃代码中引用该DLL，以期使键盘钩子正常运行，并且不会引起任何明显的输入滞后，但是那没用也可以。

键盘钩在C ++中作为.exe运行时运行完美，但是当我将其编译为DLL并在C＃中运行时，它引起了与以前相同的问题-大量的输入滞后和回调函数似乎没有被调用。

如果有人想尝试，请在这里找到代码：

KeyboardHook.cpp

#include "KeyboardHook.h"
#include <iostream>

#define __event void KeyDown(int key), KeyUp(int key);

using namespace Hooks;

void KeyDown(int key)
{
    std::cout << "KeyDown
";
}

void KeyUp(int key)
{
    std::cout << "KeyUp
";
}

LRESULT CALLBACK KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    if (nCode == HC_ACTION)
    {
        PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT)lParam;

        switch (wParam)
        {
            case WM_KEYDOWN:
            case WM_SYSKEYDOWN:
                KeyDown(p->vkCode);
                break;
            case WM_KEYUP:
            case WM_SYSKEYUP:
                KeyUp(p->vkCode);
                break;
        }
    }

    // Not processing keys so always return CallNextHookEx
    return(CallNextHookEx(NULL, nCode, wParam, lParam));
}

void KeyboardHook::Install() {
    // Install keyboard hook
    keyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardProc, 0, 0);
    std::cout << "Installed
";
}

void KeyboardHook::Uninstall() {
    // Unhook keyboard hook
    UnhookWindowsHookEx(keyboardHook);
}

KeyboardHook.h

#include <Windows.h>

HHOOK keyboardHook;

namespace Hooks 
{
    class KeyboardHook
    {
    public:
        __declspec(dllexport) void Install();
        __declspec(dllexport) void Uninstall();
    };
}

Program.cs

using System;
using System.Runtime.InteropServices;

namespace HelloMyNameIsSpindiNiceToMeetYou
{
    class Program
    {
        private const string hooksPath = @"C:PathToHooks.dll";

        // If EntryPoint doesn't work, yours might be different
        // https://docs.microsoft.com/en-us/dotnet/framework/interop/identifying-functions-in-dlls
        //
        // "For example, you can use dumpbin /exports Hooks.dll [...] to obtain function names." 
        // you need to be in the folder with the dll for above to work in Command Prompt for VS
        [DllImport(hooksPath, EntryPoint = "?Install@KeyboardHook@Hooks@@QEAAXXZ", CallingConvention = CallingConvention.Cdecl)]
        private extern static void Install();

        static void Main(string[] args)
        {
            Install();

            // keep console app running
            while (true)
            {
                continue;
            }

            // or keep it running with this
            // Console.ReadKey();
        }
    }
}