Is it possible to use Win32 Hooks in Qt applications

Question

I like to know if its possible to use win32 keyboard hook function (SetWindowsHookEx , SetWindowsHookEx ) in a Qt application.

If possible pls provide a sample code on using SetWindowsHookEx , SetWindowsHookEx functions in Qt.

//Update as of 18 Feb 2010 //

I havent figured out how to do that in QT yet.

But as a workaround I have created a win32 dll using vc++ express edition and placed my hook commands inside the dll functions. And I call that dll functions from Qt using QLibrary class

 /* hearder file code*/
    QLibrary *myLib;
    typedef HHOOK (*MyPrototype)(HINSTANCE);

/* source file code */
    myLib = new QLibrary( "ekhook.dll" );
    MyPrototype myFunction;
    myFunction = (MyPrototype) myLib->resolve( "Init" );

init() is the function in ekhook.dll thats being called

Pack

Answer 1

I was wondering the same thing and found this finally.. Credit goes to Voidrealms.

The video explains enough to make a working application with the following code below.

//Copied Code from YouTube Video

#include <QtCore/QCoreApplication>
#include <QDebug>
#include <QTime>
#include <QChar>
#include <iostream>
#include <windows.h>
#pragma comment(lib, "user32.lib")

HHOOK hHook = NULL;

using namespace std;

void UpdateKeyState(BYTE *keystate, int keycode) 
{
    keystate[keycode] = GetKeyState(keycode); 
}

LRESULT CALLBACK MyLowLevelKeyBoardProc(int nCode, WPARAM wParam, LPARAM lParam) 
{
    //WPARAM is WM_KEYDOWn, WM_KEYUP, WM_SYSKEYDOWN, or WM_SYSKEYUP
    //LPARAM is the key information

    qDebug() << "Key Pressed!";

    if (wParam == WM_KEYDOWN)
    {
        //Get the key information
        KBDLLHOOKSTRUCT cKey = *((KBDLLHOOKSTRUCT*)lParam);

        wchar_t buffer[5];

        //get the keyboard state
        BYTE keyboard_state[256];
        GetKeyboardState(keyboard_state);
        UpdateKeyState(keyboard_state, VK_SHIFT);
        UpdateKeyState(keyboard_state, VK_CAPITAL);
        UpdateKeyState(keyboard_state, VK_CONTROL);
        UpdateKeyState(keyboard_state, VK_MENU);

        //Get keyboard layout
        HKL keyboard_layout = GetKeyboardLayout(0);

        //Get the name
        char lpszName[0X100] = {0};

        DWORD dwMsg = 1;
        dwMsg += cKey.scanCode << 16;
        dwMsg += cKey.flags << 24;

        int i = GetKeyNameText(dwMsg, (LPTSTR)lpszName, 255);

        //Try to convert the key information
        int result = ToUnicodeEx(cKey.vkCode, cKey.scanCode, keyboard_state, buffer, 4, 0, keyboard_layout);
        buffer[4] = L'\0';

        //Print the output
        qDebug() << "Key: " << cKey.vkCode << " " << QString::fromUtf16((ushort*)buffer) << " " << QString::fromUtf16((ushort*)lpszName);

    }

    return CallNextHookEx(hHook, nCode, wParam, lParam); 
}

int main(int argc, char *argv[]) 
{
    QCoreApplication a(argc, argv);


    hHook = SetWindowsHookEx(WH_KEYBOARD_LL, MyLowLevelKeyBoardProc, NULL, 0);
    if (hHook == NULL)
    {
        qDebug() << "Hook Failed" << endl;
    }

    return a.exec(); 
}

Spray

This is not an answer for this question. I'm also searching for multiplatform Qt solution. Mugunth already know WinAPI commands, as he wrote in his question. Question was is there a Qt solution for it? – Unwonted

Answer 2

You don't need to do anything with Qt. Just follow the windows examples:

http://msdn.microsoft.com/en-us/library/ms644960(VS.85).aspx

Unruffled

Answer 3

I believe it is possible, yes. Use QWidget::winId.

Tranship

It would be great help if you can let me know a sample code showing how to use Qwidget::winId with SetWindowsHookEx. I am not sure how to us these together. – Pack