QwtPlotZoomer URGENT PROBLEM

[Raul C. <vid...@gm...>]

Hi Qwt users.
I tried to add a zoom feature to a big existing project. Unfortunately the
plot canvas is not only written in Qwt but with a mix of Qt/Qwt so sometime
I get strange behaviour.
I added a class named MoPlotZoomer to the plot object so:

This is the .h
--------------------------------------------------------------------------------------
#ifndef __MOPLOTZOOMER_H__
#define __MOPLOTZOOMER_H__
#include <qwt_plot_zoomer.h>
class QwtPlotZoomer;
class MoPlotZoomer : public QwtPlotZoomer{
public:
//default ctor
MoPlotZoomer(QwtPlotCanvas *canvas);
//dtor
virtual ~MoPlotZoomer();
protected:
//nothing
private:
//nothing
};
#endif //__MOPLOTZOOMER_H__
--------------------------------------------------------------------------------------
And this is the .cpp
--------------------------------------------------------------------------------------
#include "MoPlotZoomer.h"
//default ctor
MoPlotZoomer::MoPlotZoomer(QwtPlotCanvas *canvas) : QwtPlotZoomer(canvas)
{
setSelectionFlags(QwtPicker::DragSelection | QwtPicker::CornerToCorner);
setTrackerMode(QwtPicker::AlwaysOff);
setRubberBand(QwtPicker::NoRubberBand);
// RightButton: zoom out by 1
// Ctrl+RightButton: zoom out to full size
setMousePattern(QwtEventPattern::MouseSelect2, Qt::RightButton,
Qt::ControlModifier);
setMousePattern(QwtEventPattern::MouseSelect3, Qt::RightButton);
}
//dtor
MoPlotZoomer::~MoPlotZoomer()
{
}
--------------------------------------------------------------------------------------
The plot object is named MoPlot2D and I added the routine addZoomer() to add
the zoom and pan feature.
void MoPlot2D::addZoomer()
{
//enable zooming
zoomer = new MoPlotZoomer( qwtplot->canvas() );
zoomer->setRubberBand(QwtPicker::RectRubberBand);
zoomer->setRubberBandPen(QColor(Qt::green));
zoomer->setTrackerMode(QwtPicker::ActiveOnly);
zoomer->setTrackerPen(QColor(Qt::white));

//enable panner
panner = new QwtPlotPanner( qwtplot->canvas() );
panner->setMouseButton(Qt::MidButton);

qwtplot->replot();
zoomer->setZoomBase();
}

Some time I get strange behaiour: when I zoom in seems that I loose the plot
informations and I can't see nothing. I loose the axis values and in the
canvas the curve is not present.
And more: When I zoom out to the original size, the plot is not as at the
begin, the axis are different. So I think that if I store the axis
informations when I zoom in, I can restore them when I zoom out to the
original and set the plot axis.
I would like to execute a routine when I zoom in, zoom out by 1 and zoom out
to the original. I need to catch that events.
Can anyone say to me HOW? Please?
regards
raul