void QCustomPlot::replot(QCustomPlot::RefreshPriority refreshPriority),This method traverses QCPLayer
foreach (QCPLayer *layer, mLayers)
layer->drawToPaintBuffer();
Then, in QQuickPaintedItem->paint() , The draw method will be called again, So, how do you avoid multiple traversals ?
if (mPlot)
{
QPixmap picture( boundingRect().size().toSize() );
picture.fill(Qt::transparent);
QCPPainter qcpPainter( &picture );
mPlot->toPainter( &qcpPainter);
painter->drawPixmap( QPoint(), picture );
}