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Why is my Registered Hotkey not triggered when pressing the hotkey combination

I've implemented the user32.dll register and unregister hot key methods, but after registering a hotkey, I never get the WndProc message 0x0312 when pressing the hotkey. Can someone review my code and help me understand why I never get the 0x0312 message.
The combination of hotkeys I've tried so far:
Ctrl + Shift + F12
F12
F9
My implementation is just the most common implementation:
[DllImport("c:\\windows\\system32\\user32.dll")]
public static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);
[DllImport("c:\\windows\\system32\\user32.dll")]
public static extern bool UnregisterHotKey(IntPtr hWnd, int id);
protected override void WndProc(ref Message m) {
if(m.Msg == 0x0312) {
int id = m.WParam.ToInt32();
switch(id) {
case 0:
MessageBox.Show("Ctrl + Shift + F12 HotKey Pressed ! Do something here ... ");
break;
}
}
}
I created a singleton class to handle the registration and unregistration of hotkeys:
public class HotKeyHandler {
//Hotkey register and unregister.
[DllImport("c:\\windows\\system32\\user32.dll")]
public static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vlc);
[DllImport("c:\\windows\\system32\\user32.dll")]
public static extern bool UnregisterHotKey(IntPtr hWnd, int id);
public const int MOD_ALT = 0x0001;
public const int MOD_CONTROL = 0x0002;
public const int MOD_SHIFT = 0x0004;
public const int MOD_WIN = 0x0008;
byte ID = 0;
/// <summary>
/// Keep the constructor private due to singleton implementation
/// </summary>
private HotKeyHandler() { }
public static HotKeyHandler Instance = new HotKeyHandler();
public bool RegisterHotKey(IntPtr handle, int modifier, Key key) {
bool returnVal = RegisterHotKey(handle, ID, modifier, (int) key);
ID++;
return returnVal;
}
public void UnregisterAllHotKeys(IntPtr handle) {
for(short s = 0; s <= ID; s++) {
UnregisterHotKey(handle, s);
}
}
}
Finally I register the HotKey like this:
HotKeyHandler.Instance.RegisterHotKey(this.Handle, HotKeyHandler.MOD_CONTROL | HotKeyHandler.MOD_SHIFT, Key.F12);

I'd like to take the time to answer my own question just in case others might find themselves in the same.. rather irritating situation..
So after some digging and prodding I finally found out what was the problem, I was looking at the value for the Key ID that was passed to the RegisterHotKey method and noticed that the value I got did not match with the actual ID for the Key.
Turns out there exists two types of Key enums, there is the System.Windows.Input.Keyand the System.Windows.Forms.Keys. I was not aware of this and was using Input.Key which has different values from Forms.Keys
TL:DR
Use Forms.Keys for RegisterHotKey() and not Input.Key

intercept CTRL + Letter + Letter

I would like to intercept while I push CTRL + A + A
I read the article
How can I register a global hot key to say CTRL+SHIFT+(LETTER) using WPF and .NET 3.5?
and someone pasted a code originally posted here:
https://www.fluxbytes.com/csharp/how-to-register-a-global-hotkey-for-your-application-in-c/?unapproved=2279&moderation-hash=b3ec34d2621e0be051ed354f09c436d2#comment-2279
Anyway, I tried to change the code adding and "&" but this and some other attempt was wrong.
How can I get if I press CTRL + A + A ?
Thanks for the help!
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace GlobalHotkeyExampleForm
{
public partial class Form1 : Form
{
private void Form1_Load(object sender, EventArgs e)
{
}
[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);
[DllImport("user32.dll")]
private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
enum KeyModifier
{
None = 0,
Alt = 1,
Control = 2,
Shift = 4,
WinKey = 8
}
public Form1()
{
InitializeComponent();
int id = 0; // The id of the hotkey.
RegisterHotKey(this.Handle, id, (int)KeyModifier.Control, Keys.A.GetHashCode()); // Register ctrl + a as global hotkey.
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == 0x0312)
{
/* Note that the three lines below are not needed if you only want to register one hotkey.
* The below lines are useful in case you want to register multiple keys, which you can use a switch with the id as argument, or if you want to know which key/modifier was pressed for some particular reason. */
Keys key = (Keys)(((int)m.LParam >> 16) & 0xFFFF); // The key of the hotkey that was pressed.
KeyModifier modifier = (KeyModifier)((int)m.LParam & 0xFFFF); // The modifier of the hotkey that was pressed.
int id = m.WParam.ToInt32(); // The id of the hotkey that was pressed.
MessageBox.Show("Hotkey has been pressed!");
// do something
}
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
UnregisterHotKey(this.Handle, 0); // Unregister hotkey with id 0 before closing the form. You might want to call this more than once with different id values if you are planning to register more than one hotkey.
}
private void button1_Click(object sender, EventArgs e)
{
this.Close();
}
}
}

This is the solution that I've found to listen Key Pressure.
I took the code from "Dylan's Web" and I changed something:
https://www.dylansweb.com/2014/10/low-level-global-keyboard-hook-sink-in-c-net/
This is the class with a couple of lines more:
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Input;
namespace DesktopWPFAppLowLevelKeyboardHook
{
public class LowLevelKeyboardListener
{
private const int WH_KEYBOARD_LL = 13;
private const int WM_KEYDOWN = 0x0100;
private const int WM_KEYUP = 0x101;
private const int WM_SYSKEYDOWN = 0x104;
private const int WM_SYSKEYUP = 0x105;
[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);
public delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);
public event EventHandler<KeyPressedArgs> OnKeyPressed;
private LowLevelKeyboardProc _proc;
private IntPtr _hookID = IntPtr.Zero;
public LowLevelKeyboardListener()
{
_proc = HookCallback;
}
public void HookKeyboard()
{
_hookID = SetHook(_proc);
}
public void UnHookKeyboard()
{
UnhookWindowsHookEx(_hookID);
}
private 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 IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN || wParam == (IntPtr)WM_SYSKEYDOWN)
{
int vkCode = Marshal.ReadInt32(lParam);
int status = 1;
if (OnKeyPressed != null) { OnKeyPressed(this, new KeyPressedArgs(KeyInterop.KeyFromVirtualKey(vkCode), status)); }
}
else if (nCode >= 0 && wParam == (IntPtr)WM_KEYUP || wParam == (IntPtr)WM_SYSKEYUP)
{
int vkCode = Marshal.ReadInt32(lParam);
int status = 0;
if (OnKeyPressed != null) { OnKeyPressed(this, new KeyPressedArgs(KeyInterop.KeyFromVirtualKey(vkCode), status)); }
}
return CallNextHookEx(_hookID, nCode, wParam, lParam);
}
}
public class KeyPressedArgs : EventArgs
{
public Key KeyPressed { get; private set; }
public int KeyStatus { get; private set; }
public KeyPressedArgs(Key key, int status)
{
KeyPressed = key;
KeyStatus = status;
}
}
}
This is the Form:
using DesktopWPFAppLowLevelKeyboardHook;
using System;
using System.Windows.Forms;
namespace AppLowLevelKeyboardHook
{
public partial class Form1 : Form
{
private LowLevelKeyboardListener _listener;
public int ctrlStatus;
public int cStatus;
public Form1()
{
InitializeComponent();
}
private void Window_Loaded(object sender, EventArgs e)
{
_listener = new LowLevelKeyboardListener();
_listener.OnKeyPressed += _listener_OnKeyPressed;
_listener.HookKeyboard();
}
private void _listener_OnKeyPressed(object sender, KeyPressedArgs e)
{
this.textBox_DisplayKeyboardInput.Text += e.KeyPressed.ToString() + e.KeyStatus.ToString();
if (e.KeyStatus == 1 && (e.KeyPressed.ToString() == "LeftCtrl" || e.KeyStatus.ToString() == "RightCtrl"))
{
if (ctrlStatus == 0)
{
ctrlStatus = ctrlStatus + 1;
timer1.Start();
}
}
else if (e.KeyStatus == 1 && e.KeyPressed.ToString() == "C")
{
if (ctrlStatus == 1 && (cStatus == 0 || cStatus == 2))
{
cStatus = cStatus + 1;
}
}
//no need to wait that CTRL will be released
//else if (e.KeyStatus == 0 && (e.KeyPressed.ToString() == "LeftCtrl" || e.KeyStatus.ToString() == "RightCtrl"))
//{
// if (ctrlStatus == 1)
// {
// ctrlStatus = ctrlStatus + 1;
// }
//}
else if (e.KeyStatus == 0 && e.KeyPressed.ToString() == "C")
{
if (ctrlStatus == 1)
{
if (cStatus == 1 || cStatus == 3)
{
cStatus = cStatus + 1;
}
}
}
}
private void timer1_Tick(object sender, EventArgs e)
{
if ((ctrlStatus == 1) && cStatus == 3 || cStatus == 4) //no need to wait that CTRL will be released (ctrlStatus == 2)
{
//do something
label1.Text = "";
label1.Refresh();
label1.Text = Clipboard.GetText(TextDataFormat.UnicodeText);
//\do something
}
ctrlStatus = 0;
cStatus = 0;
timer1.Stop();
}
private void Window_Closing(object sender, FormClosingEventArgs e)
{
_listener.UnHookKeyboard();
}
}
}
PS: originally it was WPF app but mine it's a WFA and KeyInterop is not included.
So I simply added a reference assembly to WindowsBase.dll

Yesterday I'm back on this question and finally, I did what I was searching to do but changing the strategy because with the upper code I didn't really found a solution for my target. I'm going to report why I think it can be useful to someone else and maybe someone has a different solution.
So, on the upper code, I tried to intercept CTRL+C+C and than get what use copy on the Windows Clipboard. But here it's the problem, that code registers the shortkey, so any other software can't continue to use CTRL+C. I tried to unregister the shortkey after to have cached that CTRL+C has been pressed but I've found only problems. Anyway, I don't like "to stole" a shortkey to another app, I prefer to "listen" key while they are pressed.
So here it follows the code with some comments (I'll paste the solution that I've found "listening keys pressed" adding a new answer).
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Text;
namespace GlobalHotkeyExampleForm
{
public partial class Form1 : Form
{
private void Form1_Load(object sender, EventArgs e)
{
}
public int shortkey = 0;
[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);
[DllImport("user32.dll")]
private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
enum KeyModifier
{
None = 0,
Alt = 1,
Control = 2,
Shift = 4,
WinKey = 8
}
public Form1()
{
InitializeComponent();
int id = 0; // The id of the hotkey.
RegisterHotKey(this.Handle, id, (int)KeyModifier.Control, Keys.C.GetHashCode()); // Register CTRL + C as global hotkey.
}
protected override void WndProc(ref Message m)
{
base.WndProc(ref m);
if (m.Msg == 0x0312)
{
/* Note that the three lines below are not needed if you only want to register one hotkey.
* The below lines are useful in case you want to register multiple keys, which you can use a switch with the id as argument, or if you want to know which key/modifier was pressed for some particular reason. */
Keys key = (Keys)(((int)m.LParam >> 16) & 0xFFFF); // The key of the hotkey that was pressed.
KeyModifier modifier = (KeyModifier)((int)m.LParam & 0xFFFF); // The modifier of the hotkey that was pressed.
int id = m.WParam.ToInt32(); // The id of the hotkey that was pressed.
if (modifier == KeyModifier.Control && key == Keys.C)
{
shortkey = shortkey + 1;
label1.Text = (shortkey.ToString());
//if I enebale this code it works partially. The UnregisterHotKey and RegisterHotKey works perfectly and alone also SendKeys works prefectly, but together it doesn't:
//it doesn't recognize that CTRL is still pressed and I don't want to do CTRL C + CTRL C and I don't like "to stole" the shortkey from other apps!;
//I tried to use SendKeys to resend CTRL C or onlt CTRL but it doens't work and it creates only Register problems
//UnregisterHotKey(this.Handle, 0); //unregister the hotkey catching
//SendKeys.Send("^c"); //send key to active application (it doesn't matter if this is the application)
////register the hotkey catching as C only
//RegisterHotKey(this.Handle, id, (int)KeyModifier.Control, Keys.C.GetHashCode());
//SendKeys.Send("^c");
//SendKeys.Send("^");
timer1.Start();
}
//MessageBox.Show("Hotkey has been pressed!");
// do something
}
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
UnregisterHotKey(this.Handle, 0); // Unregister hotkey with id 0 before closing the form. You might want to call this more than once with different id values if you are planning to register more than one hotkey.
}
private void button1_Click(object sender, EventArgs e)
{
this.Close();
}
private void timer1_Tick(object sender, EventArgs e)
{
if (shortkey == 2)
{
string returnMyText = Clipboard.GetText(TextDataFormat.Text);
}
shortkey = 0;
timer1.Stop();
}
}
}

Global hotkey taking exclusive use of keys

I'm currently using this code for hotkey manager that i found on another post here:
public class HotKeyReader
{
public static event EventHandler<HotKeyEventArgs> HotKeyPressed;
public static int RegisterHotKey(Keys key, KeyModifiers modifiers)
{
int id = System.Threading.Interlocked.Increment(ref _id);
RegisterHotKey(_wnd.Handle, id, (uint)modifiers, (uint)key);
return id;
}
public static bool UnregisterHotKey(int id)
{
return UnregisterHotKey(_wnd.Handle, id);
}
protected static void OnHotKeyPressed(HotKeyEventArgs e)
{
if (HotKeyReader.HotKeyPressed != null)
{
HotKeyReader.HotKeyPressed(null, e);
}
}
private static MessageWindow _wnd = new MessageWindow();
private class MessageWindow : Form
{
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_HOTKEY)
{
HotKeyEventArgs e = new HotKeyEventArgs(m.LParam);
HotKeyReader.OnHotKeyPressed(e);
}
base.WndProc(ref m);
}
private const int WM_HOTKEY = 0x312;
}
[DllImport("user32")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, uint fsModifiers, uint vk);
[DllImport("user32")]
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
}
But when a hotkey is registered, for example, just using "a", you can no longer use "a" anywhere else in windows. Is there anyway to stop this from happening? Or is there a better code out there that does the same.

A keyboard hook, installed with SetWindowsHook, would allow observing the keystroke without affecting its delivery to the application.

Global hotkey in console application

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);
}
}

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!");
}
}
}

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
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
}
}
}

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();
}
}

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
}
}

Change the key being pressed with C#

Hey, I'm trying to write a program in C# that will track the pressing of certain keys (using a keyboard hook), and send different ones instead.
For instance, when I press the A key it will instead send the Q key.
I used http://www.codeproject.com/KB/cs/CSLLKeyboardHook.aspx this for my hooks and tried to use the SendKeys function, but I get an exception about the garbage collector destroying some object inside the hook class.

First you need to hook up the keys.
With this class you can register a global shortcut, I'm skipping the explanation, but you can read it here.
public class KeyboardHook
{
[DllImport("user32.dll")]
private static extern bool RegisterHotKey(IntPtr hWnd, int id, int fsModifiers, int vk);
[DllImport("user32.dll")]
private static extern bool UnregisterHotKey(IntPtr hWnd, int id);
public enum Modifiers
{
None = 0x0000,
Alt = 0x0001,
Control = 0x0002,
Shift = 0x0004,
Win = 0x0008
}
int modifier;
int key;
IntPtr hWnd;
int id;
public KeyboardHook(int modifiers, Keys key, Form f)
{
this.modifier = modifiers;
this.key = (int)key;
this.hWnd = f.Handle;
id = this.GetHashCode();
}
public override int GetHashCode()
{
return modifier ^ key ^ hWnd.ToInt32();
}
public bool Register()
{
return RegisterHotKey(hWnd, id, modifier, key);
}
public bool Unregister()
{
return UnregisterHotKey(hWnd, id);
}
}
Then on your form you have to register the shortcut
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
KeyboardHook hook = new KeyboardHook((int)KeyboardHook.Modifiers.None, Keys.A, this);
hook.Register(); // registering globally that A will call a method
}
protected override void WndProc(ref Message m)
{
if (m.Msg == 0x0312)
HandleHotkey(); // A, which was registered before, was pressed
base.WndProc(ref m);
}
private void HandleHotkey()
{
// instead of A send Q
KeyboardManager.PressKey(Keys.Q);
}
}
And here the class to manage Keyboard press and release events.
public class KeyboardManager
{
public const int INPUT_KEYBOARD = 1;
public const int KEYEVENTF_KEYUP = 0x0002;
public struct KEYDBINPUT
{
public Int16 wVk;
public Int16 wScan;
public Int32 dwFlags;
public Int32 time;
public Int32 dwExtraInfo;
public Int32 __filler1;
public Int32 __filler2;
}
public struct INPUT
{
public Int32 type;
public KEYDBINPUT ki;
}
[DllImport("user32")]
public static extern int SendInput(int cInputs, ref INPUT pInputs, int cbSize);
public static void HoldKey(Keys vk)
{
INPUT input = new INPUT();
input.type = INPUT_KEYBOARD;
input.ki.dwFlags = 0;
input.ki.wVk = (Int16)vk;
SendInput(1, ref input, Marshal.SizeOf(input));
}
public static void ReleaseKey(Keys vk)
{
INPUT input = new INPUT();
input.type = INPUT_KEYBOARD;
input.ki.dwFlags = KEYEVENTF_KEYUP;
input.ki.wVk = (Int16)vk;
SendInput(1, ref input, Marshal.SizeOf(input));
}
public static void PressKey(Keys vk)
{
HoldKey(vk);
ReleaseKey(vk);
}
}
I've tested it on this textarea which I'm writing to, when I pressed A it was sending Q.
I'm not sure what will be the behavior on Warcraft III, maybe they have blocked to prevent some kind of bot or something...

And when you look at your hook class what is the source of the problem? It sounds like a resource not being managed properly.
Realize that if you are planning on doing this as some sort of practical joke these never go over well because generally of the inability to turn these off. Also recognize that this type of seemingly unethical topic will not likely get much support.