Global hotkey in console application
Asked Answered
U

4

42

Does anyone know how to use the RegisterHotKey/UnregisterHotKey API calls in a console application? I assume that setting up/removing the hotkey is the same, but how do I get the call back when the key was pressed?

Every example I see is for Winforms, and uses protected override void WndProc(ref Message m){...}, which isn't available to me.


update: what I have is below, but the event is never hit. I thought it could be because when you load ConsoleShell it does block further execution, but even if I put SetupHotkey into a different thread nothing happens. Any thoughts?
class Program
{
    static void Main(string[] args)
    {
        new Hud().Init(args);
    }
}

class Hud
{
    int keyHookId;


    public void Init(string[] args)
    {
        SetupHotkey();
        InitPowershell(args);
        Cleanup();
    }

    private void Cleanup()
    {
        HotKeyManager.UnregisterHotKey(keyHookId);
    }

    private void SetupHotkey()
    {
        keyHookId = HotKeyManager.RegisterHotKey(Keys.Oemtilde, KeyModifiers.Control);
        HotKeyManager.HotKeyPressed += new EventHandler<HotKeyEventArgs>(HotKeyManager_HotKeyPressed);
    }

    void HotKeyManager_HotKeyPressed(object sender, HotKeyEventArgs e)
    {
        //never executed
        System.IO.File.WriteAllText("c:\\keyPressed.txt", "Hotkey pressed");
    }

    private static void InitPowershell(string[] args)
    {
        var config = RunspaceConfiguration.Create();
        ConsoleShell.Start(config, "", "", args);
    }
}
Ultun answered 6/9, 2010 at 23:18 Comment(0)
C
73

What you can do is Create a hidden window in your Console application which is used to handle the hotkey notification and raise an event.

The code HERE demonstrates the principal. HERE is an article on handling messages in a Console application, using this you should be able to enhance HotKeyManager to run in a Console Application.

The following update to the HotKeyManager creates a background thread which runs the message loop and handles the windows messages.

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

namespace ConsoleHotKey
{
  public static class HotKeyManager
  {
    public static event EventHandler<HotKeyEventArgs> HotKeyPressed;

    public static int RegisterHotKey(Keys key, KeyModifiers modifiers)
    {
      _windowReadyEvent.WaitOne();
      int id = System.Threading.Interlocked.Increment(ref _id);
      _wnd.Invoke(new RegisterHotKeyDelegate(RegisterHotKeyInternal), _hwnd, id, (uint)modifiers, (uint)key);
      return id;
    }

    public static void UnregisterHotKey(int id)
    {
      _wnd.Invoke(new UnRegisterHotKeyDelegate(UnRegisterHotKeyInternal), _hwnd, id);
    }

    delegate void RegisterHotKeyDelegate(IntPtr hwnd, int id, uint modifiers, uint key);
    delegate void UnRegisterHotKeyDelegate(IntPtr hwnd, int id);

    private static void RegisterHotKeyInternal(IntPtr hwnd, int id, uint modifiers, uint key)
    {      
      RegisterHotKey(hwnd, id, modifiers, key);      
    }

    private static void UnRegisterHotKeyInternal(IntPtr hwnd, int id)
    {
      UnregisterHotKey(_hwnd, id);
    }    

    private static void OnHotKeyPressed(HotKeyEventArgs e)
    {
      if (HotKeyManager.HotKeyPressed != null)
      {
        HotKeyManager.HotKeyPressed(null, e);
      }
    }

    private static volatile MessageWindow _wnd;
    private static volatile IntPtr _hwnd;
    private static ManualResetEvent _windowReadyEvent = new ManualResetEvent(false);
    static HotKeyManager()
    {
      Thread messageLoop = new Thread(delegate()
        {
          Application.Run(new MessageWindow());
        });
      messageLoop.Name = "MessageLoopThread";
      messageLoop.IsBackground = true;
      messageLoop.Start();      
    }

    private class MessageWindow : Form
    {
      public MessageWindow()
      {
        _wnd = this;
        _hwnd = this.Handle;
        _windowReadyEvent.Set();
      }

      protected override void WndProc(ref Message m)
      {
        if (m.Msg == WM_HOTKEY)
        {
          HotKeyEventArgs e = new HotKeyEventArgs(m.LParam);
          HotKeyManager.OnHotKeyPressed(e);
        }

        base.WndProc(ref m);
      }

      protected override void SetVisibleCore(bool value)
      {
        // Ensure the window never becomes visible
        base.SetVisibleCore(false);
      }

      private const int WM_HOTKEY = 0x312;
    }

    [DllImport("user32", SetLastError=true)]
    private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

    [DllImport("user32", SetLastError = true)]
    private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

    private static int _id = 0;
  }


  public class HotKeyEventArgs : EventArgs
  {
    public readonly Keys Key;
    public readonly KeyModifiers Modifiers;

    public HotKeyEventArgs(Keys key, KeyModifiers modifiers)
    {
      this.Key = key;
      this.Modifiers = modifiers;
    }

    public HotKeyEventArgs(IntPtr hotKeyParam)
    {
      uint param = (uint)hotKeyParam.ToInt64();
      Key = (Keys)((param & 0xffff0000) >> 16);
      Modifiers = (KeyModifiers)(param & 0x0000ffff);
    }
  }

  [Flags]
  public enum KeyModifiers
  {
    Alt = 1,
    Control = 2,
    Shift = 4,
    Windows = 8,
    NoRepeat = 0x4000
  }
}

Here is an example of using HotKeyManager from a Console application

using System;
using System.Windows.Forms;

namespace ConsoleHotKey
{
  class Program
  {
    static void Main(string[] args)
    {
      HotKeyManager.RegisterHotKey(Keys.A, KeyModifiers.Alt);
      HotKeyManager.HotKeyPressed += new EventHandler<HotKeyEventArgs>(HotKeyManager_HotKeyPressed);
      Console.ReadLine();      
    }

    static void HotKeyManager_HotKeyPressed(object sender, HotKeyEventArgs e)
    {
      Console.WriteLine("Hit me!");
    }
  }
}
Classy answered 6/9, 2010 at 23:25 Comment(20)
I have tried that many times, and the event never seems to get fired. Is there something else I am missing?Ultun
@joe, I have added an update which includes the reworked HotKeyManager to support console applications.Classy
Hey @ChrisTaylor what are the advantages of using ManualResetEvent and Interlocked.Increment here? Thanks!Fideicommissary
@ByteBlast, the event is usd to ensure that the background message pump is setup and the hidden window handle exists before allowing hot keys to be registered. By using interlocked increment the code ensures it is safe to be executed from multiple threads.Classy
@ChrisTaylor Thanks. I'm asking this because I don't see the point in using the ManualRestEvent (that's not to say there is no point). I understand exactly what it is doing but I can't seem to produce a scenario on my computer where the ManualResetEvent is needed. Did you include it for good measure or is there some sounder logic behind this? Appreciate it alot mate, thanks again.Fideicommissary
Because the window is created in a separate thread there is a potential for a race condition which the event protects against. Of course as with any multi-threaded code problems only present at the worst possible time ie. when it goes to the client. So the event ensures that regardless of timing issues due to multiple cores etc. the code will work and not hit a corner case. Without the event you might experience unexplained situations where the hot key registration fails.Classy
How about doing this in a service? I can't seem to get this (or any other example in SO search results) to work. The service compiles and runs fine, but the event does not fire.Singly
The problem with a service is that it does not run in the users interactive desktop session. This is for security reasons. But since hotkeys assume an interactive session you should get away with creating an app that runs at startup, maybe have a tray icon etc.Classy
@ChrisTaylor: Great code! however it does not work for multiple hotkeys. Pressing one hotkey will run all functions for all hotkeys. Is it possible to change it to run for multiple hotkeys?Felid
@M0HS3N - This is the way the underlying windows hotkey support works. The WM_HOTKEY message is generated for any hotkey and then you check the parameters to determine which hotkey was pressed. The wrapper follows this pattern, when the HotKeyPressed event is raised you can check the HotKeyEventArgs to determine which hotkey combination it was that triggered the event. You can of course develop a higher level abstraction of this, but the sample provides everything you need to do that.Classy
This is a great solution, but it did not appear to be thread safe when attempting to update form items. As a note to others, consider using the solution at #142503 for use when changing form items inside HotKeyManager_HotKeyPressed method.Margrettmarguerie
how check hotkeys with if-else ? example: if(Keys.A, KeyModifiers.Alt) {...} etc else ??!Prosthodontist
@GooliveR, register the hotkey combinations you are interested in using HotKeyManager.RegisterHotKey. In the event handler you can check which hotkey triggered the event by inspecting the HotKeyEventArgs instance passed to the event handler.Classy
@ChrisTaylor, Can you give an example please?Prosthodontist
@Prosthodontist - Comments are probably not the place to do that. Would you like to post a complete question, then I or someone more knowledgeable could answer that.Classy
This worked great for me. I'm running an Office Addin and create a new file for HotKeyManager, I then took the initialization code and put it in ThisAddIn_Startup.Sinistrad
@ChrisTaylor Could you please take a look at this use case of your code where it throws an error in debug mode, but not release: #58944759 Thank you!Tonl
@ChrisTaylor I'm using this solution and it sort of works. However, I have an issue where it seems like keys (randomly) doesn't work. I have ALTGR + F1 up to F12 as hotkeys, and when the program's running, for instance, ALTGR + F3 doesn't work. Then you can close the program at open it again, it will then start working. Can you help me out as to why this is happening?Herwig
@Herwig - It might be best to post a new question with the minimal sample code that can be used to reproduce the issue.Classy
@ChrisTaylor Thanks for the response! I already did that, check it out here: #72084214Herwig
C
11

I just wanted to offer an alternative solution.

I was answering a question for someone who was using this script and I figured this might help someone else who has trouble setting up a global key hook.

Edit: Don't forget to add a reference to System.Windows.Forms

You can do this by selecting Project🢂Add Reference and checking System.Windows.Forms

enter image description here

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

namespace ConsoleKeyhook
{
class Hooky
{
    ///////////////////////////////////////////////////////////
    //A bunch of DLL Imports to set a low level keyboard hook
    ///////////////////////////////////////////////////////////
    [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);

    ////////////////////////////////////////////////////////////////
    //Some constants to make handling our hook code easier to read
    ////////////////////////////////////////////////////////////////
    private const int WH_KEYBOARD_LL = 13;                    //Type of Hook - Low Level Keyboard
    private const int WM_KEYDOWN = 0x0100;                    //Value passed on KeyDown
    private const int WM_KEYUP = 0x0101;                      //Value passed on KeyUp
    private static LowLevelKeyboardProc _proc = HookCallback; //The function called when a key is pressed
    private static IntPtr _hookID = IntPtr.Zero;
    private static bool CONTROL_DOWN = false;                 //Bool to use as a flag for control key

    public static void Main()
    {
        _hookID = SetHook(_proc);  //Set our hook
        Application.Run();         //Start a standard application method loop
    }

    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) //A Key was pressed down
        {
            int vkCode = Marshal.ReadInt32(lParam);           //Get the keycode
            string theKey = ((Keys)vkCode).ToString();        //Name of the key
            Console.Write(theKey);                            //Display the name of the key
            if (theKey.Contains("ControlKey"))                //If they pressed control
            {
                CONTROL_DOWN = true;                          //Flag control as down
            }
            else if (CONTROL_DOWN && theKey == "B")           //If they held CTRL and pressed B
            {
                Console.WriteLine("\n***HOTKEY PRESSED***");  //Our hotkey was pressed
            }
            else if (theKey == "Escape")                      //If they press escape
            {
                UnhookWindowsHookEx(_hookID);                 //Release our hook
                Environment.Exit(0);                          //Exit our program
            }
        }
        else if (nCode >= 0 && wParam == (IntPtr)WM_KEYUP) //KeyUP
        {
            int vkCode = Marshal.ReadInt32(lParam);        //Get Keycode
            string theKey = ((Keys)vkCode).ToString();     //Get Key name
            if (theKey.Contains("ControlKey"))             //If they let go of control
            {
                CONTROL_DOWN = false;                      //Unflag control
            }
        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam); //Call the next hook
    }
}
}
Cloister answered 1/8, 2014 at 1:37 Comment(4)
I was using this same approach and found that hot keys mapped in other applications will propagate using hooks. So, eg, F12 in Chrome raises the inspector. Using user32.RegisterHotKey will supposedly prevent this (according to other sources).Ardene
This is a global keyhook - it's made to allow propagation from any other application.Cloister
If you want to prevent other applications (like Chrome) from seeing your hotkey, add return (IntPtr) 0; after your hotkey is detected code. (I think - untested but IIRC that's how you do it). It's either 0 or 1 - can't remember which.Cloister
This solution executes within the context of the same process so no violations are encountered when trying to modify controls. Thanks!!Antigone
S
3

I came up with a solution based on Chris' answer that uses WPF instead of WinForms:

public sealed class GlobalHotkeyRegister : IGlobalHotkeyRegister, IDisposable
{
    private const int WmHotkey = 0x0312;

    private Application _app;
    private readonly Dictionary<Hotkey, Action> _hotkeyActions;

    public GlobalHotkeyRegister()
    {
        _hotkeyActions = new Dictionary<Hotkey, Action>();
        var startupTcs = new TaskCompletionSource<object>();

        Task.Run(() =>
        {
            ComponentDispatcher.ThreadPreprocessMessage += OnThreadPreProcessMessage;

            _app = new Application();
            _app.Startup += (s, e) => startupTcs.SetResult(null);
            _app.Run();
        });

        startupTcs.Task.Wait();
    }

    public void Add(Hotkey hotkey, Action action)
    {
        _hotkeyActions.Add(hotkey, action);

        var keyModifier = (int) hotkey.KeyModifier;
        var key = KeyInterop.VirtualKeyFromKey(hotkey.Key);

        _app.Dispatcher.Invoke(() =>
        {
            if (!RegisterHotKey(IntPtr.Zero, hotkey.GetHashCode(), keyModifier, key))
                throw new Win32Exception(Marshal.GetLastWin32Error());
        });       
    }

    public void Remove(Hotkey hotkey)
    {
        _hotkeyActions.Remove(hotkey);

        _app.Dispatcher.Invoke(() =>
        {
            if (!UnregisterHotKey(IntPtr.Zero, hotkey.GetHashCode()))
                throw new Win32Exception(Marshal.GetLastWin32Error());
        });
    }

    private void OnThreadPreProcessMessage(ref MSG msg, ref bool handled)
    {
        if (msg.message != WmHotkey)
            return;

        var key = KeyInterop.KeyFromVirtualKey(((int) msg.lParam >> 16) & 0xFFFF);
        var keyModifier = (KeyModifier) ((int) msg.lParam & 0xFFFF);

        var hotKey = new Hotkey(keyModifier, key);
        _hotkeyActions[hotKey]();
    }

    public void Dispose()
    {
        _app.Dispatcher.InvokeShutdown();
    }

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
}

public class Hotkey
{
    public Hotkey(KeyModifier keyModifier, Key key)
    {
        KeyModifier = keyModifier;
        Key = key;
    }

    public KeyModifier KeyModifier { get; }
    public Key Key { get; }

    #region ToString(), Equals() and GetHashcode() overrides
}

[Flags]
public enum KeyModifier
{
    None = 0x0000,
    Alt = 0x0001,
    Ctrl = 0x0002,
    Shift = 0x0004,
    Win = 0x0008,
    NoRepeat = 0x4000
}

To use this, you need to add references to PresentationFramework.dll and WindowsBase.dll.

public static void Main()
{
    using (var hotkeyManager = new GlobalHotkeyManager())
    {
        var hotkey = new Hotkey(KeyModifier.Ctrl | KeyModifier.Alt, Key.S);
        hotkeyManager.Add(hotkey, () => System.Console.WriteLine(hotkey));

        System.Console.ReadKey();
    }
}
Syphon answered 29/5, 2016 at 15:26 Comment(0)
P
0

Changed the HotKeyManager class

public static class HotKeyManager
    {
        public static event EventHandler<HotKeyEventArgs> HotKeyPressed;

        public static int RegisterHotKey(Keys key, HotKeyEventArgs.KeyModifiers modifiers)
        {
            _windowReadyEvent.WaitOne();
            _wnd.Invoke(new RegisterHotKeyDelegate(RegisterHotKeyInternal), _hwnd, Interlocked.Increment(ref _id), (uint)modifiers, (uint)key);
            return Interlocked.Increment(ref _id);
        }

        public static void UnregisterHotKey(int id)
        {
            _wnd.Invoke(new UnRegisterHotKeyDelegate(UnRegisterHotKeyInternal), _hwnd, id);
        }

        private delegate void RegisterHotKeyDelegate(IntPtr hwnd, int id, uint modifiers, uint key);
        private delegate void UnRegisterHotKeyDelegate(IntPtr hwnd, int id);

        private static void RegisterHotKeyInternal(IntPtr hwnd, int id, uint modifiers, uint key)
        {
            RegisterHotKey(hWnd: hwnd, id: id, fsModifiers: modifiers, vk: key);
        }

        private static void UnRegisterHotKeyInternal(IntPtr hwnd, int id)
        {
            UnregisterHotKey(_hwnd, id);
        }

        private static void OnHotKeyPressed(HotKeyEventArgs e)
        {
            HotKeyPressed?.Invoke(null, e);
        }

        private static volatile MessageWindow _wnd;
        private static volatile IntPtr _hwnd;
        private static ManualResetEvent _windowReadyEvent = new ManualResetEvent(false);

        static HotKeyManager()
        {
            new Thread(delegate ()
                        {
                            Application.Run(new MessageWindow());
                        })
            {
                Name = "MessageLoopThread",
                IsBackground = true
            }.Start();
        }

        private class MessageWindow : Form
        {
            public MessageWindow()
            {
                _wnd = this;
                _hwnd = Handle;
                _windowReadyEvent.Set();
            }

            protected override void WndProc(ref Message m)
            {
                if (m.Msg == WM_HOTKEY)
                {
                    var e = new HotKeyEventArgs(hotKeyParam: m.LParam);
                    OnHotKeyPressed(e);
                }

                base.WndProc(m: ref m);
            }

            protected override void SetVisibleCore(bool value)
            {
                // Ensure the window never becomes visible
                base.SetVisibleCore(false);
            }

            private const int WM_HOTKEY = 0x312;
        }

        [DllImport("user32", SetLastError = true)]
        private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);

        [DllImport("user32", SetLastError = true)]
        private static extern bool UnregisterHotKey(IntPtr hWnd, int id);

        private static int _id = 0;
    }

Class HotKeyEventArgs:

public partial class HotKeyEventArgs : EventArgs
    {
        public readonly Keys Key;
        public readonly KeyModifiers Modifiers;

        public HotKeyEventArgs(Keys key, KeyModifiers modifiers)
        {
            Key = key;
            Modifiers = modifiers;
        }

        public HotKeyEventArgs(IntPtr hotKeyParam)
        {
            Key = (Keys)(((uint)hotKeyParam.ToInt64() & 0xffff0000) >> 16);
            Modifiers = (KeyModifiers)((uint)hotKeyParam.ToInt64() & 0x0000ffff);
        }
    }

And class: HotKeyEventArgs

public partial class HotKeyEventArgs
    {
        [Flags]
        public enum KeyModifiers
        {
            Alt = 1,
            Control = 2,
            Shift = 4,
            Windows = 8,
            NoRepeat = 0x4000
        }
    }
Prosthodontist answered 15/12, 2017 at 11:20 Comment(0)

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