Extending QML - Property Value Source Example

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#include "happybirthdaysong.h"
#include <QTimer>

HappyBirthdaySong::HappyBirthdaySong(QObject *parent)
: QObject(parent), m_line(-1)
{
    setName(QString());
    QTimer *timer = new QTimer(this);
    QObject::connect(timer, &QTimer::timeout, this, &HappyBirthdaySong::advance);
    timer->start(1000);
}

void HappyBirthdaySong::setTarget(const QQmlProperty &p)
{
    m_target = p;
}

QString HappyBirthdaySong::name() const
{
    return m_name;
}

void HappyBirthdaySong::setName(const QString &name)
{
    m_name = name;

    m_lyrics.clear();
    m_lyrics << "Happy birthday to you,";
    m_lyrics << "Happy birthday to you,";
    m_lyrics << "Happy birthday dear " + m_name + ",";
    m_lyrics << "Happy birthday to you!";
    m_lyrics << "";
}

void HappyBirthdaySong::advance()
{
    m_line = (m_line + 1) % m_lyrics.count();

    m_target.write(m_lyrics.at(m_line));
}