Cattura della tastiera globale nell'applicazione C#

Question

Voglio catturare una scorciatoia da tastiera nella mia applicazione e attivare una finestra di dialogo da visualizzare se l'utente preme una combinazione di tasti anche al di fuori dell'app. Simile a Ctrl di Google Desktop Search, Ctrl per far apparire la finestra di dialogo di ricerca.

Ho provato con alcuni moduli gancio tastiera là fuori che, in fondo usare Win32 interoperabilità per ottenere questo effetto, ma ogni implementazione ho provato legami verso il basso la tastiera in una certa misura a cui iniziare a ricevere i comportamenti strani quando l'applicazione è fare qualcosa intensiva. Come caricare una grande quantità di dati, questo causerebbe il blocco della tastiera e del mouse.

Sto cercando una soluzione leggera che consenta di eseguire questa operazione senza collegare tastiera e mouse.

Answer 1

Stephen Toub wrote a great article sull'attuazione ganci tastiera globali in C#:

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

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

    public static void Main() 
    { 
     _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 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) 
     { 
      int vkCode = Marshal.ReadInt32(lParam); 
      Console.WriteLine((Keys)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); 
} 

Answer 2

Se un tasto di scelta rapida globale sarebbe sufficiente, quindi RegisterHotKey farebbe il trucco

Answer 3

Ecco il mio codice che funziona:

using System; 
using System.ComponentModel; 
using System.Diagnostics; 
using System.Runtime.InteropServices; 

namespace SnagFree.TrayApp.Core 
{ 
    class GlobalKeyboardHookEventArgs : HandledEventArgs 
    { 
     public GlobalKeyboardHook.KeyboardState KeyboardState { get; private set; } 
     public GlobalKeyboardHook.LowLevelKeyboardInputEvent KeyboardData { get; private set; } 

     public GlobalKeyboardHookEventArgs(
      GlobalKeyboardHook.LowLevelKeyboardInputEvent keyboardData, 
      GlobalKeyboardHook.KeyboardState keyboardState) 
     { 
      KeyboardData = keyboardData; 
      KeyboardState = keyboardState; 
     } 
    } 

    //Based on https://gist.github.com/Stasonix 
    class GlobalKeyboardHook : IDisposable 
    { 
     public event EventHandler<GlobalKeyboardHookEventArgs> KeyboardPressed; 

     public GlobalKeyboardHook() 
     { 
      _windowsHookHandle = IntPtr.Zero; 
      _user32LibraryHandle = IntPtr.Zero; 
      _hookProc = LowLevelKeyboardProc; // we must keep alive _hookProc, because GC is not aware about SetWindowsHookEx behaviour. 

      _user32LibraryHandle = LoadLibrary("User32"); 
      if (_user32LibraryHandle == IntPtr.Zero) 
      { 
       int errorCode = Marshal.GetLastWin32Error(); 
       throw new Win32Exception(errorCode, $"Failed to load library 'User32.dll'. Error {errorCode}: {new Win32Exception(Marshal.GetLastWin32Error()).Message}."); 
      } 



      _windowsHookHandle = SetWindowsHookEx(WH_KEYBOARD_LL, _hookProc, _user32LibraryHandle, 0); 
      if (_windowsHookHandle == IntPtr.Zero) 
      { 
       int errorCode = Marshal.GetLastWin32Error(); 
       throw new Win32Exception(errorCode, $"Failed to adjust keyboard hooks for '{Process.GetCurrentProcess().ProcessName}'. Error {errorCode}: {new Win32Exception(Marshal.GetLastWin32Error()).Message}."); 
      } 
     } 

     protected virtual void Dispose(bool disposing) 
     { 
      if (disposing) 
      { 
       // because we can unhook only in the same thread, not in garbage collector thread 
       if (_windowsHookHandle != IntPtr.Zero) 
       { 
        if (!UnhookWindowsHookEx(_windowsHookHandle)) 
        { 
         int errorCode = Marshal.GetLastWin32Error(); 
         throw new Win32Exception(errorCode, $"Failed to remove keyboard hooks for '{Process.GetCurrentProcess().ProcessName}'. Error {errorCode}: {new Win32Exception(Marshal.GetLastWin32Error()).Message}."); 
        } 
        _windowsHookHandle = IntPtr.Zero; 

        // ReSharper disable once DelegateSubtraction 
        _hookProc -= LowLevelKeyboardProc; 
       } 
      } 

      if (_user32LibraryHandle != IntPtr.Zero) 
      { 
       if (!FreeLibrary(_user32LibraryHandle)) // reduces reference to library by 1. 
       { 
        int errorCode = Marshal.GetLastWin32Error(); 
        throw new Win32Exception(errorCode, $"Failed to unload library 'User32.dll'. Error {errorCode}: {new Win32Exception(Marshal.GetLastWin32Error()).Message}."); 
       } 
       _user32LibraryHandle = IntPtr.Zero; 
      } 
     } 

     ~GlobalKeyboardHook() 
     { 
      Dispose(false); 
     } 

     public void Dispose() 
     { 
      Dispose(true); 
      GC.SuppressFinalize(this); 
     } 

     private IntPtr _windowsHookHandle; 
     private IntPtr _user32LibraryHandle; 
     private HookProc _hookProc; 

     delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam); 

     [DllImport("kernel32.dll")] 
     private static extern IntPtr LoadLibrary(string lpFileName); 

     [DllImport("kernel32.dll", CharSet = CharSet.Auto)] 
     private static extern bool FreeLibrary(IntPtr hModule); 

     /// <summary> 
     /// The SetWindowsHookEx function installs an application-defined hook procedure into a hook chain. 
     /// You would install a hook procedure to monitor the system for certain types of events. These events are 
     /// associated either with a specific thread or with all threads in the same desktop as the calling thread. 
     /// </summary> 
     /// <param name="idHook">hook type</param> 
     /// <param name="lpfn">hook procedure</param> 
     /// <param name="hMod">handle to application instance</param> 
     /// <param name="dwThreadId">thread identifier</param> 
     /// <returns>If the function succeeds, the return value is the handle to the hook procedure.</returns> 
     [DllImport("USER32", SetLastError = true)] 
     static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, int dwThreadId); 

     /// <summary> 
     /// The UnhookWindowsHookEx function removes a hook procedure installed in a hook chain by the SetWindowsHookEx function. 
     /// </summary> 
     /// <param name="hhk">handle to hook procedure</param> 
     /// <returns>If the function succeeds, the return value is true.</returns> 
     [DllImport("USER32", SetLastError = true)] 
     public static extern bool UnhookWindowsHookEx(IntPtr hHook); 

     /// <summary> 
     /// The CallNextHookEx function passes the hook information to the next hook procedure in the current hook chain. 
     /// A hook procedure can call this function either before or after processing the hook information. 
     /// </summary> 
     /// <param name="hHook">handle to current hook</param> 
     /// <param name="code">hook code passed to hook procedure</param> 
     /// <param name="wParam">value passed to hook procedure</param> 
     /// <param name="lParam">value passed to hook procedure</param> 
     /// <returns>If the function succeeds, the return value is true.</returns> 
     [DllImport("USER32", SetLastError = true)] 
     static extern IntPtr CallNextHookEx(IntPtr hHook, int code, IntPtr wParam, IntPtr lParam); 

     [StructLayout(LayoutKind.Sequential)] 
     public struct LowLevelKeyboardInputEvent 
     { 
      /// <summary> 
      /// A virtual-key code. The code must be a value in the range 1 to 254. 
      /// </summary> 
      public int VirtualCode; 

      /// <summary> 
      /// A hardware scan code for the key. 
      /// </summary> 
      public int HardwareScanCode; 

      /// <summary> 
      /// The extended-key flag, event-injected Flags, context code, and transition-state flag. This member is specified as follows. An application can use the following values to test the keystroke Flags. Testing LLKHF_INJECTED (bit 4) will tell you whether the event was injected. If it was, then testing LLKHF_LOWER_IL_INJECTED (bit 1) will tell you whether or not the event was injected from a process running at lower integrity level. 
      /// </summary> 
      public int Flags; 

      /// <summary> 
      /// The time stamp stamp for this message, equivalent to what GetMessageTime would return for this message. 
      /// </summary> 
      public int TimeStamp; 

      /// <summary> 
      /// Additional information associated with the message. 
      /// </summary> 
      public IntPtr AdditionalInformation; 
     } 

     public const int WH_KEYBOARD_LL = 13; 
     //const int HC_ACTION = 0; 

     public enum KeyboardState 
     { 
      KeyDown = 0x0100, 
      KeyUp = 0x0101, 
      SysKeyDown = 0x0104, 
      SysKeyUp = 0x0105 
     } 

     public const int VkSnapshot = 0x2c; 
     //const int VkLwin = 0x5b; 
     //const int VkRwin = 0x5c; 
     //const int VkTab = 0x09; 
     //const int VkEscape = 0x18; 
     //const int VkControl = 0x11; 
     const int KfAltdown = 0x2000; 
     public const int LlkhfAltdown = (KfAltdown >> 8); 

     public IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam) 
     { 
      bool fEatKeyStroke = false; 

      var wparamTyped = wParam.ToInt32(); 
      if (Enum.IsDefined(typeof(KeyboardState), wparamTyped)) 
      { 
       object o = Marshal.PtrToStructure(lParam, typeof(LowLevelKeyboardInputEvent)); 
       LowLevelKeyboardInputEvent p = (LowLevelKeyboardInputEvent)o; 

       var eventArguments = new GlobalKeyboardHookEventArgs(p, (KeyboardState)wparamTyped); 

       EventHandler<GlobalKeyboardHookEventArgs> handler = KeyboardPressed; 
       handler?.Invoke(this, eventArguments); 

       fEatKeyStroke = eventArguments.Handled; 
      } 

      return fEatKeyStroke ? (IntPtr)1 : CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam); 
     } 
    } 
} 

Utilizzo:

using System; 
using System.Windows.Forms; 

namespace SnagFree.TrayApp.Core 
{ 
    internal class Controller : IDisposable 
    { 
     private GlobalKeyboardHook _globalKeyboardHook; 

     public void SetupKeyboardHooks() 
     { 
      _globalKeyboardHook = new GlobalKeyboardHook(); 
      _globalKeyboardHook.KeyboardPressed += OnKeyPressed; 
     } 

     private void OnKeyPressed(object sender, GlobalKeyboardHookEventArgs e) 
     { 
      //Debug.WriteLine(e.KeyboardData.VirtualCode); 

      if (e.KeyboardData.VirtualCode != GlobalKeyboardHook.VkSnapshot) 
       return; 

      // seems, not needed in the life. 
      //if (e.KeyboardState == GlobalKeyboardHook.KeyboardState.SysKeyDown && 
      // e.KeyboardData.Flags == GlobalKeyboardHook.LlkhfAltdown) 
      //{ 
      // MessageBox.Show("Alt + Print Screen"); 
      // e.Handled = true; 
      //} 
      //else 

      if (e.KeyboardState == GlobalKeyboardHook.KeyboardState.KeyDown) 
      { 
       MessageBox.Show("Print Screen"); 
       e.Handled = true; 
      } 
     } 

     public void Dispose() 
     { 
      _globalKeyboardHook?.Dispose(); 
     } 
    } 
}