How can I move a QSlider slider handle with the keyboard?

Question

I can't figure out how I can move a slider handle of a QSlider in QT. When I press for example A( I want to move coursor left) and D(I want move coursor right) so I did

(void) new QShortcut(Qt::Key_A, this, SLOT(moveTickmarkLeft()));
    (void) new QShortcut(Qt::Key_D, this, SLOT(moveTickmarkRight()));

implementation:

void LCDRange::moveTickmarkLeft()
{
    slider->setSliderPosition(slider->sliderPosition - 1);
}

void LCDRange::moveTickmarkRight()
{
    slider->setSliderPosition(slider->sliderPosition + 1);
}

the same I did using function setTickPosition(), what is the difference between setSliderPosition() and setTickPosition() how can I implement my idea, thanx in advance for any help

Answer 1

I believe using setSliderPosition method is the correct way of moving your slider in code. setTickPosition set the way how the tick mark should be drawn, so I guess, this is not smth you need. As for intercepting keyboard events: you can install an event filter to your form ui controls and put your slider moving logic there. Below is an example. More details on event filter here

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    // install event filter to ui controls of the window
    ui->textEdit->installEventFilter(this);
    ui->pushButton->installEventFilter(this);
    ui->horizontalSlider->installEventFilter(this);
}

// event filter implementation
bool MainWindow::eventFilter(QObject* watched, QEvent* event)
{
    if (event->type() == QEvent::KeyPress )
    {
        QKeyEvent* keyEvent = (QKeyEvent*)event;
        if (keyEvent->key()=='A')
        {
            qDebug() << "move slider";
            ui->horizontalSlider->setSliderPosition(ui->horizontalSlider->sliderPosition()+1);
        }
        else if (keyEvent->key()=='B')
        {
            qDebug() << "move slider";
            ui->horizontalSlider->setSliderPosition(ui->horizontalSlider->sliderPosition()-1);
        }

    }
    return QMainWindow::eventFilter(watched, event);
}

hope this helps, regards