QwtPicker with QwtHistogram

[cptpingu]

It's much much clearer for me now. Thanks for the explanation.

Using the "event_filter" example I found in the Qwt source, I tried to implement the move event, but it don't works. The "selected" works fine.

Can I have some help on this piece of code ?

HistogramPlot.hh

#ifndef HISTOGRAMPLOT_HH_
# define HISTOGRAMPLOT_HH_
 
# include <qwt_plot.h>
# include <qwt_picker.h>
# include <qwt_plot_picker.h>
 
class HistogramPlot : public QwtPlot
{
  Q_OBJECT
public:
  HistogramPlot(QWidget* = 0);
 
private:
  void populate();
 
private Q_SLOTS:
  void showItem(QwtPlotItem*, bool on);
  void moved(const QPoint& pos);
  void selected(const QPointF& pos);
 
protected:
  QwtScaleDiv fixedNumberScaleDiv() const;
  QwtPlotPicker* picker_;
};
 
#endif /* !HISTOGRAMPLOT_HH_ */

#ifndef HISTOGRAMPLOT_HH_
# define HISTOGRAMPLOT_HH_

# include <qwt_plot.h>
# include <qwt_picker.h>
# include <qwt_plot_picker.h>

class HistogramPlot : public QwtPlot
{
  Q_OBJECT
public:
  HistogramPlot(QWidget* = 0);

private:
  void populate();

private Q_SLOTS:
  void showItem(QwtPlotItem*, bool on);
  void moved(const QPoint& pos);
  void selected(const QPointF& pos);

protected:
  QwtScaleDiv fixedNumberScaleDiv() const;
  QwtPlotPicker* picker_;
};

#endif /* !HISTOGRAMPLOT_HH_ */

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HistogramPlot.cc

HistogramPlot::HistogramPlot(QWidget* parent)
  : QwtPlot(parent)
{
  [...]
 
  picker_ = new QwtPlotPicker(this->canvas());
  picker_->setStateMachine(new QwtPickerClickPointMachine);
  connect(picker_, SIGNAL(moved(const QPoint&)),
          SLOT(moved(const QPoint&)));
  connect(picker_, SIGNAL(selected(const QPointF&)),
          SLOT(selected(const QPointF&)));
}
 
void HistogramPlot::moved(const QPoint& pos)
{
    QString info;
    info.sprintf("Freq=%g, Ampl=%g, Phase=%g",
        invTransform(QwtPlot::xBottom, pos.x()),
        invTransform(QwtPlot::yLeft, pos.y()),
        invTransform(QwtPlot::yRight, pos.y())
    );
    qDebug() << info;
}
 
void HistogramPlot::selected(const QPointF& pos)
{
  QString info;
  info.sprintf("Freq=%g, Ampl=%g, Phase=%g",
      invTransform(QwtPlot::xBottom, pos.x()),
      invTransform(QwtPlot::yLeft, pos.y()),
      invTransform(QwtPlot::yRight, pos.y())
  );
  qDebug() << info;
}

HistogramPlot::HistogramPlot(QWidget* parent)
  : QwtPlot(parent)
{
  [...]

  picker_ = new QwtPlotPicker(this->canvas());
  picker_->setStateMachine(new QwtPickerClickPointMachine);
  connect(picker_, SIGNAL(moved(const QPoint&)),
          SLOT(moved(const QPoint&)));
  connect(picker_, SIGNAL(selected(const QPointF&)),
          SLOT(selected(const QPointF&)));
}

void HistogramPlot::moved(const QPoint& pos)
{
    QString info;
    info.sprintf("Freq=%g, Ampl=%g, Phase=%g",
        invTransform(QwtPlot::xBottom, pos.x()),
        invTransform(QwtPlot::yLeft, pos.y()),
        invTransform(QwtPlot::yRight, pos.y())
    );
    qDebug() << info;
}

void HistogramPlot::selected(const QPointF& pos)
{
  QString info;
  info.sprintf("Freq=%g, Ampl=%g, Phase=%g",
      invTransform(QwtPlot::xBottom, pos.x()),
      invTransform(QwtPlot::yLeft, pos.y()),
      invTransform(QwtPlot::yRight, pos.y())
  );
  qDebug() << info;
}

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Edit: I just understand that "moved" is use when you drag something, not when you move the mouse. I don't found a signal/slot which deal with mouse move. How can I implement that ?