O'Reilly logo

Game Programming using Qt 5 Beginner's Guide - Second Edition by Lorenz Haas, Witold Wysota, Pavel Strakhov

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Time for action – Drawing an oscillogram

Let's further extend our widget to become a simple oscillogram renderer. For that, we have to make the widget remember a set of values and draw them as a series of lines.

Let's start by adding a QVector<quint16> member variable that holds a list of unsigned 16-bit integer values. We will also add slots for adding values to the list and for clearing the list, as shown:

class Widget : public QWidget
{
    // ...
public slots:
    void addPoint(unsigned yVal) {
        m_points << qMax(0u, yVal);
        update();
    }
    void clear() {
        m_points.clear();
        update();
    }
protected:
    // ...
    QVector<quint16> m_points;
}; 

Note that each modification of the list invokes a method called update(). This schedules a paint event so that our widget ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required