How to customize https://www.qcustomplot.com/index.php/demos/colormapdemo

QFile ioData(QCoreApplication::applicationDirPath()+"/../filename");
{
if(!ioData.open(QIODevice::ReadOnly | QIODevice::Text))
//QMessageBox::information(0,"info",ioData.errorString());
return;

}
QString line;
QTextStream stream(&ioData);

while (!stream.atEnd()) {
line = stream.readLine();
QStringList values = line.split(" "" ", QString::SkipEmptyParts);
//xcordinate values[0];
//ycordinate values[1];
//value determining the color values[2];
}
How to generate a contour graph using the QCustomPlot