背景键按下监听器

Question

我有一个简单的窗口形式应用程序,当我按空格键时打开大写锁定,如果我按下一个字母则将其关闭.

问题是我必须专注于窗口才能工作(最顶层也不起作用,最顶层不会只关注它只是将窗口显示在所有其他未聚焦的窗口之上).

任何人都知道即使我在记事本中写作,我怎么能让它工作？

Answer 1

密钥记录可以用于顽皮的东西,并且操纵Caps Lock似乎相当奇怪,但由于信息已经公开,并且您比我更了解您的用户故事,我已经发布了一个解决方案.

这是一个基于MSDN论坛中C#中的键盘记录代码发布的代码片段的示例.

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

class Program
{
    private const int WH_KEYBOARD_LL = 13;
    private const int WM_KEYDOWN = 0x0100;
    private static LowLevelKeyboardProc _proc = HookCallback;
    private static IntPtr _hookID = IntPtr.Zero;
    private static bool lastKeyWasLetter = false;

    [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);

    [DllImport("user32.dll")]
    static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, UIntPtr dwExtraInfo);

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

    [STAThread]
    static void Main(string[] args)
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        _hookID = SetHook(_proc);
        Application.Run();

        UnhookWindowsHookEx(_hookID);
    }

    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 static void ToggleCapsLock()
    {
        const int KEYEVENTF_EXTENDEDKEY = 0x1;
        const int KEYEVENTF_KEYUP = 0x2;

        UnhookWindowsHookEx(_hookID);
        keybd_event(0x14, 0x45, KEYEVENTF_EXTENDEDKEY, (UIntPtr)0);
        keybd_event(0x14, 0x45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, (UIntPtr)0);
        _hookID = SetHook(_proc);
    }

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)
        {
            if (lastKeyWasLetter)
            {
                if (Control.IsKeyLocked(System.Windows.Forms.Keys.CapsLock))
                {
                    ToggleCapsLock();
                }
                lastKeyWasLetter = false;
            }
            Keys key = (Keys)Marshal.ReadInt32(lParam);            
            if (key == Keys.Space)
            {
                if (!Control.IsKeyLocked(System.Windows.Forms.Keys.CapsLock))
                {
                    ToggleCapsLock();
                }
            }
            else if (key >= Keys.A && key <= Keys.Z)
            {
                lastKeyWasLetter = true;
            }
        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);
    }
}

将其粘贴到Visual Studio中的新Windows应用程序的Program.cs中进行试用.

如果您截取按键事件以打开和关闭Caps Lock,则在应用程序处理事件之前拦截该事件.这意味着当按下字母键时关闭Caps Lock将导致您键入的应用程序接收小写字母,甚至直接在空格后.

我假设你试图强制每个单词中第一个字母的大写(如果是这样,你可能需要处理其他键,如Return也是如此),所以我的代码片段只会在下一个键上关闭Caps Lock按下一封信后的事件.请注意,您不能只是尝试捕获该键,因为当您快速键入时,您可以按住初始键,直到您按下以下键为止.