WinForms中如何捕获全局键盘事件？

SetWindowsHookEx

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

public class GlobalKeyboardHook : IDisposable
{
    private const int WH_KEYBOARD_LL = 13; // 低级键盘钩子
    private const int WM_KEYDOWN = 0x0100; // 按键按下消息
    private const int WM_SYSKEYDOWN = 0x0104; // 系统按键按下消息 (如Alt键组合)

    public event KeyEventHandler KeyDown; // 暴露给外部的键盘按下事件

    private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
    private LowLevelKeyboardProc _proc; // 钩子回调委托
    private IntPtr _hookID = IntPtr.Zero; // 钩子句柄

    private Control _targetControl; // 用于将事件封送回UI线程的控件

    // 构造函数，需要传入一个Control实例，以便安全地将事件封送回UI线程
    public GlobalKeyboardHook(Control targetControl)
    {
        _proc = HookCallback; // 初始化回调函数
        _targetControl = targetControl ?? throw new ArgumentNullException(nameof(targetControl), "Target control cannot be null for UI thread marshaling.");
    }

    // 安装钩子
    public void Hook()
    {
        _hookID = SetHook(_proc);
    }

    // 卸载钩子
    public void Unhook()
    {
        if (_hookID != IntPtr.Zero)
        {
            UnhookWindowsHookEx(_hookID);
            _hookID = IntPtr.Zero;
        }
    }

    // 实际安装钩子的P/Invoke调用
    private IntPtr SetHook(LowLevelKeyboardProc proc)
    {
        using (Process curProcess = Process.GetCurrentProcess())
        using (ProcessModule curModule = curProcess.MainModule)
        {
            // 获取当前模块的句柄，这是SetWindowsHookEx需要的
            return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0);
        }
    }

    // 钩子回调函数，当键盘事件发生时会被系统调用
    private IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        // nCode < 0 表示钩子链中的下一个钩子已经处理了消息，我们不应该处理
        if (nCode >= 0 && (wParam == (IntPtr)WM_KEYDOWN || wParam == (IntPtr)WM_SYSKEYDOWN))
        {
            // 获取按键的虚拟键码
            int vkCode = Marshal.ReadInt32(lParam);
            Keys key = (Keys)vkCode;

            // 获取修饰键状态 (Ctrl, Shift, Alt)
            bool ctrl = (Control.ModifierKeys & Keys.Control) == Keys.Control;
            bool shift = (Control.ModifierKeys & Keys.Shift) == Keys.Shift;
            bool alt = (Control.ModifierKeys & Keys.Alt) == Keys.Alt;

            // 创建KeyEventArgs实例
            KeyEventArgs e = new KeyEventArgs(key |
                                              (ctrl ? Keys.Control : Keys.None) |
                                              (shift ? Keys.Shift : Keys.None) |
                                              (alt ? Keys.Alt : Keys.None));

            // 将事件封送回UI线程，确保UI操作的线程安全
            if (_targetControl != null && _targetControl.InvokeRequired)
            {
                _targetControl.Invoke((MethodInvoker)delegate {
                    KeyDown?.Invoke(this, e);
                });
            }
            else
            {
                KeyDown?.Invoke(this, e);
            }

            // 如果事件被处理（例如，你希望阻止按键传递给其他应用程序），可以返回 (IntPtr)1
            // if (e.Handled) return (IntPtr)1;
        }

        // 调用钩子链中的下一个钩子
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }

    // P/Invoke 声明
    [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);

    // 实现IDisposable接口，确保钩子在对象销毁时被卸载
    public void Dispose()
    {
        Unhook();
    }
}

// 在Form1.cs中
public partial class Form1 : Form
{
    private GlobalKeyboardHook _globalHook;

    public Form1()
    {
        InitializeComponent();
        // 实例化全局钩子，并传入当前窗体实例
        _globalHook = new GlobalKeyboardHook(this);
        _globalHook.KeyDown += GlobalHook_KeyDown; // 订阅事件
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        _globalHook.Hook(); // 在窗体加载时安装钩子
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        _globalHook.Unhook(); // 在窗体关闭时卸载钩子
        _globalHook.Dispose(); // 释放资源
    }

    private void GlobalHook_KeyDown(object sender, KeyEventArgs e)
    {
        // 在这里处理全局键盘事件
        // 例如，显示按下的键
        this.Text = $"全局按键: {e.KeyCode} (Ctrl: {e.Control}, Shift: {e.Shift}, Alt: {e.Alt})";

        // 如果你希望某个按键被你的应用“消费”掉，不传递给其他应用，可以设置e.Handled = true;
        // 但这需要在HookCallback中根据e.Handled的值来决定是否调用CallNextHookEx((IntPtr)1)
        // e.Handled = true; // 示例：阻止所有全局按键
    }
}

this.Text = "..."

InvalidOperationException

Control.Invoke

Control.BeginInvoke

GlobalKeyboardHook

HookCallback