How to write correctly an event handler

[Tanuki-no Torigava]

And please look at this once again:

A widget must call setFocusPolicy() to accept focus initially and have focus in order to receive a key press event.

Did you call setFocusPolicy?

[Lykurg]

And please look at this once again:



Did you call setFocusPolicy?

Guys read the docs carefully! First ignore() and accept() are not necessary! and setFocusPolicy is also not required. The user can activate the widget himself using the mouse or tab...

So a simple implementation would be:

// eats space
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            QWidget::keyPressEvent(pe);
            break;
    }
}
 
// just plays a sound whenever space is pressed
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            break;
    }
    QWidget::keyPressEvent(pe);
}

// eats space
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            QWidget::keyPressEvent(pe);
            break;
    }
}

// just plays a sound whenever space is pressed
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            break;
    }
    QWidget::keyPressEvent(pe);
}

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assuming QWidget is your base class. And such problems should be better posted in the Newbie section.

[franco.amato]

Guys read the docs carefully! First ignore() and accept() are not necessary! and setFocusPolicy is also not required. The user can activate the widget himself using the mouse or tab...

So a simple implementation would be:

// eats space
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            QWidget::keyPressEvent(pe);
            break;
    }
}
 
// just plays a sound whenever space is pressed
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            break;
    }
    QWidget::keyPressEvent(pe);
}

// eats space
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            QWidget::keyPressEvent(pe);
            break;
    }
}

// just plays a sound whenever space is pressed
void WaveWidget::keyPressEvent( QKeyEvent* pe )
{
    switch( pe->key() )
    {
        case Qt::Key_Space:
            {
                qDebug() << "Space pressed";
                m_wave->playSound();
            }
            break;
 
        default:
            break;
    }
    QWidget::keyPressEvent(pe);
}

To copy to clipboard, switch view to plain text mode 

assuming QWidget is your base class. And such problems should be better posted in the Newbie section.

Sorry but in the second case I always pass the event to the base class and in the first one only in the default case...which is the difference?

[Lykurg]

Sorry but in the second case I always pass the event to the base class and in the first one only in the default case...which is the difference?

If you have a QWidget as base class: No difference. But e.g. your base class is a QLineEdit, then in the first case the user can not write a space in the line edit. Which one you use depends on your requirements I don't know.