C＃随时随地检测ESC按键

Question

我有一个正在运行的C＃窗口应用程序，并且即使我的应用程序没有焦点，也想在任何地方按ESC时都将其关闭。我该如何实施？

我发现了一些连接键盘，它是“我不知道并且不理解”的“低级控制”。

Answer 1

使用此类：

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

namespace myNameSpace
{
    class InterceptKeys
    {
        private const int WH_KEYBOARD_LL = 13;
        private const int WM_KEYDOWN = 0x0100;
        private const int WM_ALTDOWN = 0x0104;
        private static LowLevelKeyboardProc _proc = HookCallback;
        private static IntPtr _hookID = IntPtr.Zero;

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

        public static void Stop()
        {
            UnhookWindowsHookEx(_hookID);
        }

        public static event KeyEventHandler OnKeyDown;

        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);
            }
        }

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

        private static IntPtr HookCallback(
            int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0 && (wParam == (IntPtr)WM_KEYDOWN || wParam == (IntPtr)WM_ALTDOWN))
            {
                var vkCode = (Keys)Marshal.ReadInt32(lParam);
                OnKeyDown(null, new KeyEventArgs(vkCode));
            }
            return CallNextHookEx(_hookID, nCode, wParam, 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);
    }
}

通过这种方式：

myNameSpace.InterceptKeys.OnKeyDown+= new KeyEventHandler(myKeyDown);

myNameSpace.InterceptKeys.Start();

onKeyDown可以像这样：

void myKeyDown(object sender, KeyEventArgs e)
{
    // Some code for closing you form
    // or any thing you need after press Esc
    // with e.KeyCode
};