QCustomPlot: mouse interaction on secondary axis

Question

I have a QCustomPlot with all the 4 axes enabled and with these interactions activated:

my_w.plot->setInteractions(QCP::iRangeDrag | QCP::iRangeZoom | QCP::iSelectAxes | QCP::iSelectLegend | QCP::iSelectPlottables);

Now by swiping on an xAxis or yAxis I can change the scale, but when I do the same over xAxis2 or yAxis2 nothing happens.

how do I set interaction over the secondary axes?

EDIT:

I've discovered setRangeDragAxes and setRangeZoomAxes:

my_w.plot->axisRect()->setRangeDragAxes(my_w.plot->xAxis2,my_w.plot->yAxis2);
my_w.plot->axisRect()->setRangeZoomAxes(my_w.plot->xAxis2,my_w.plot->yAxis2);

now I can drag/and zoom axes, and everything it's almost ok: drag works ok, but When I zoom by swiping with two fingers, both xAxis2 and yAxis2 zoom together.

Answer 1

You can make only one axis zoom by selecting the axis you want to zoom and add a mouseWheel slot.

Connecting mouse wheel signal to your slot:

connect(my_w.plot, SIGNAL(mouseWheel(QWheelEvent*)), this, SLOT(mouseWheel()));

Implement mouse wheel slot:

void YourDialog::mouseWheel()
{
  // if an axis is selected, only allow the direction of that axis to be zoomed
  // if no axis is selected, both directions may be zoomed

  if (my_w.plot->xAxis->selectedParts().testFlag(QCPAxis::spAxis)){
    my_w.plot->axisRect()->setRangeZoomAxes(my_w.plot->xAxis,my_w.plot->yAxis);
    my_w.plot->axisRect()->setRangeZoom(my_w.plot->xAxis->orientation());
  }
  else if (my_w.plot->yAxis->selectedParts().testFlag(QCPAxis::spAxis)){
    my_w.plot->axisRect()->setRangeZoomAxes(my_w.plot->xAxis,my_w.plot->yAxis);
    my_w.plot->axisRect()->setRangeZoom(my_w.plot->yAxis->orientation());
  }
  else if (my_w.plot->xAxis2->selectedParts().testFlag(QCPAxis::spAxis)){
    my_w.plot->axisRect()->setRangeZoomAxes(my_w.plot->xAxis2,my_w.plot->yAxis2);
    my_w.plot->axisRect()->setRangeZoom(my_w.plot->xAxis2->orientation());
  }
  else if (my_w.plot->yAxis2->selectedParts().testFlag(QCPAxis::spAxis)){
    my_w.plot->axisRect()->setRangeZoomAxes(my_w.plot->xAxis2,my_w.plot->yAxis2);
    my_w.plot->axisRect()->setRangeZoom(my_w.plot->yAxis2->orientation());
  }
  else
    my_w.plot->axisRect()->setRangeZoom(Qt::Horizontal|Qt::Vertical);
}

You may change the last case to setRangeZoom(0) if you don't want to make any zoom when none of the axes are selected.

Take a look at the Interaction Example for more options.