I want to show system time information on x-axis in real time in my plot. In the code I wrote below, every time the system clock changes, all the clock information on the x-axis changes. I don't want the clock of the past drawings to change. how can i fix this.

QSharedPointer<QCPAxisTickerTime> timeTicker(new QCPAxisTickerTime);
QDateTime currentTime = QDateTime::currentDateTime();
QString time = currentTime.toString("hh:mm:ss");

plot output;