Capture keyboard arrows in Qt

Question

Capture keyboard arrows in Qt

Navigation

#1 by (0 votes)

0

I have been doing a school project in which they asked me to create the 2048 game, I created it on the console line as a base, and then I did the graphic design, but when I wanted to implement it I found the problem that checked at the time of starting the application, I started to review, and it turns out that in the cycle in which I ask the user a character "getch ()" is returning me in ascii a "-1", (before installing the filter of events I returned a "-32") so it enters, cycled, and then it does not come out anymore, with what the application ticks me and does not respond.

I would like to know how to capture the arrows on the keyboard, since it is the simplest thing, the other idea that I had was that in a block of text I would capture the letters, but it seems annoying to the end user.

Here is the code of my program:

G2048::G2048(QWidget *parent) :
    QMainWindow(parent), ui(new Ui::G2048){

    ui->setupUi(this);
    EventKeyGame* evento = new EventKeyGame;
    ui->pushButton_Start->installEventFilter(evento);

}

void G2048::on_pushButton_Start_clicked(){

    int casillaRandom = 0;
    char tecla;
    int tablero[4][4];
    limpiarTablero(tablero);

    cargarCasilla(tablero, &casillaRandom);
    cargarCasilla(tablero, &casillaRandom);

    arriba(tablero);
    imprimirTablero(tablero);


     do{
        tecla = getch();
        cout<<(int)tecla<<endl;
            switch(tecla){
                case 72:
                    arriba(tablero);
                    cargarCasilla(tablero, &casillaRandom);
                    imprimirTablero(tablero);
                    break;
                case 75:
                    izquierda(tablero);
                    cargarCasilla(tablero, &casillaRandom);
                    imprimirTablero(tablero);
                    break;
                case 77:
                    derecha(tablero);
                    cargarCasilla(tablero, &casillaRandom);
                    imprimirTablero(tablero);
                    break;
                case 80:
                    abajo(tablero);
                    cargarCasilla(tablero, &casillaRandom);
                    imprimirTablero(tablero);
                    break;
                default:
                    break;
            }
        }while(true);

}

And the event filter that is installed on the button is this:

bool EventKeyGame::eventFilter(QObject *obj, QEvent *event){

    if (event->type() == QEvent::KeyPress) {
        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
        if(keyEvent->key() == Qt::Key_Up || keyEvent->key() == Qt::Key_Down || keyEvent->key() == Qt::Key_Left || keyEvent->key() == Qt::Key_Right){
            qDebug("Valid Key");
        }
        return true;
    } else {
        return QObject::eventFilter(obj, event);
    }

}

What about the event filter I saw in these links:

Captures keystrokes with QT and C ++

link

Try also to capture with Open GL, but I can not know if my teacher will have the header.

Another idea I had was to make use of graphic buttons, but it is still a bit annoying to move the mouse, besides that passing the variable board to each button would be long to program.

c++ teclado opengl qt

asked by Dykeiichi 12.03.2018 в 20:29

source

1 answer

Error in array not defined in php and Mysql Error serving JavaScript Windows Server 2012 IIS 6.2

score 0 · Accepted Answer

You should not use an infinite loop or take a long time of a GUI, if you are doing this your design is not optimal, and I recommend redesigning your application.

In a GUI the tasks must be done when an event occurs, in your case when a certain button is pressed. There are several alternatives to catch those events, one of the simplest is to overwrite the event keyPressEvent that has all QWidget as shown below:

*. h

class G2048 : public QMainWindow
{
[..]
protected:
    void keyPressEvent(QKeyEvent *event);
};

*. cpp

void G2048::keyPressEvent(QKeyEvent *event)
{
    switch (event->key()) {
    case Qt::Key_Up:
        qDebug()<<"arriba";
        break;
    case Qt::Key_Down:
        qDebug()<<"abajo";
        break;
    case Qt::Key_Left:
        qDebug()<<"izquierda";
        break;
    case Qt::Key_Right:
        qDebug()<<"derecha";
        break;
    default:
        break;
    }
}