class VerticalMarker : public QCPItemLine { Q_OBJECT public: VerticalMarker(double xCoord, QCustomPlot* plot, QColor color); VerticalMarker(double xCoord, QCustomPlot* plot, QColor color, QColor selectedColor); void setXCoord(double xCoordl); double getXCoord(); void setPixelXCoord(double xPixel); void updateHeight(int height); double getPixelXCoord(); void updateAbsPosition(); protected: double mXCoord; double mPixelXCoord; int mPixelHeight; QCustomPlot* mPlot; }; VerticalMarker::VerticalMarker(double xCoord, QCustomPlot* plot, QColor color, QColor selectedColor): QCPItemLine (plot), mXCoord(xCoord), mPlot(plot) { setPen(QPen(color)); setSelectedPen(QPen(selectedColor)); setParent(plot); setClipToAxisRect(false); start->setType( QCPItemPosition::PositionType::ptAbsolute); end->setType( QCPItemPosition::PositionType::ptAbsolute); setVisible(true); mPixelXCoord = mPlot->xAxis->coordToPixel(mXCoord); }

I have a problem that could be easily showed by images and I'll try to describe:

I have a plot made by many axisrects piled one over the other. they ideally have all the same x coordinates but I show the labels only on the bottom one. each axis rect has its own y axis.

I need to plot a vertical bar that I can make start from over the bottom X axis and reaches the top of the plot.

I found so far 2 ways and none works as it should:

1. I draw a QCPItemLine with points of ptPlotCoords type, NOT clipped to Axis Rect. It works correctly when I compose the whole plot and its positioned where it's expected BUT it obviously goes over the tick labels of the bottom axis.

2. I draw a QCPItemLine - as in the code above - with points of ptAbsolute type, yet NOT clipped to AxisRect and I set its position in pixel converting from the x coordinate that's the data I know. The problem is that when I compose the plot it's not known exactly how much the tick labels on the Y axes will be wide so converting coordinate in pixel gives the wrong x pixel. I haven't found in which function the real position of the axes has been already calculated so that I can finally calculate the correct x pixel of my verticall bar.