Overload119 Overload119 - 2 months ago 43
C# Question

C# Low-Level Keyboard Hook Not Working

This is the code for my keyhooking class, but it doesn't work. I was wondering if someone can tell me why? I'm instansiating it in another Console application. The debug message gives the proper output, but the keyboard hook simply doesn't catch keys. I was hoping if someone could tell me why.

namespace GlobalHooks
{
public class InterceptKeys
{
private const int WH_KEYBOARD_LL = 13;
private const int WM_KEYDOWN = 0x0100;

private static IntPtr _hookID = IntPtr.Zero;
private static String keysHooked = String.Empty;

private static LowLevelHookProc keyboardHook;

public delegate IntPtr LowLevelHookProc(int nCode, Int32 wParam, IntPtr lParam);
public delegate void KeyboardHandleFunction(int vkCode);
public static event KeyboardHandleFunction keyHookReturn;

public InterceptKeys(KeyboardHandleFunction func)
{
keyHookReturn = func;
keyboardHook = new LowLevelHookProc(HookCallback);
}

public static void debug()
{
Console.Write("\n[Success!] _hookID: "+_hookID);
Console.Write("\n[Success!] keyboardProc: "+keyboardHook.ToString());
}

private IntPtr SetupHook(LowLevelHookProc keyProcess)
{
using (Process curProcess = Process.GetCurrentProcess())
using (ProcessModule curModule = curProcess.MainModule)
{
return SetWindowsHookEx(WH_KEYBOARD_LL, keyProcess,
GetModuleHandle(curModule.ModuleName), 0);
}
}

public void Hook()
{
_hookID = SetupHook(keyboardHook);
debug();
}

public void Unhook()
{
UnhookWindowsHookEx(_hookID);
}


public static void OnCallbackReturn(int nCode)
{
if (keyHookReturn != null)
{
keyHookReturn(nCode);
}
else
{
throw new Exception();
}
}

public static IntPtr HookCallback(int nCode, Int32 wParam, IntPtr lParam)
{
Console.WriteLine("Calledback"Wink;
if (nCode >= 0 && wParam == WM_KEYDOWN)
{
int vkCode = Marshal.ReadInt32(lParam);
Console.WriteLine((Keys)vkCode);
OnCallbackReturn(nCode);
}
return CallNextHookEx((int)_hookID, nCode, wParam, lParam);
}

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelHookProc lpfn, IntPtr hMod, uint dwThreadId);

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool UnhookWindowsHookEx(IntPtr hhk);

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr CallNextHookEx(int hhk, int nCode, int wParam, IntPtr lParam);

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetModuleHandle(string lpModuleName);
}
}

Answer

Are you calling Application.Run in your Main function?

The standard Console thread doesn't have a message loop, which is required for hooks to work properly, Application.Run takes care of that.

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