What is the elegant way to disable picker/zoomer when the plot is disabled?

[freshairfly]

I found that when the plot is disabled (by setEnabled(false) of plot's parent's parent), the picker and zoomer still works.
What is the elegant way to disable picker&zoomer when the plot is disabled?

[Cah]

I would subclass QwtPlot and reimplement changeEvent()
...
see code

#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_zoomer.h>
#include <QEvent>
 
class Plot: public QwtPlot
{
public:
    Plot(QWidget* parent=0):QwtPlot(parent)
    {
        _zoomer = new QwtPlotZoomer(this->canvas());
    }
protected:
    void changeEvent(QEvent * event)
    {
        if(event->type()==QEvent::EnabledChange)
        {
            _zoomer->setEnabled(this->isEnabled());
        }
    }
private:
    QwtPlotZoomer* _zoomer;
};
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QwtPlot* plot = new Plot;
 
    plot->setEnabled(false);
 
    plot->show();
 
    return a.exec();
}

#include <QApplication>
#include <qwt_plot.h>
#include <qwt_plot_zoomer.h>
#include <QEvent>

class Plot: public QwtPlot
{
public:
    Plot(QWidget* parent=0):QwtPlot(parent)
    {
        _zoomer = new QwtPlotZoomer(this->canvas());
    }
protected:
    void changeEvent(QEvent * event)
    {
        if(event->type()==QEvent::EnabledChange)
        {
            _zoomer->setEnabled(this->isEnabled());
        }
    }
private:
    QwtPlotZoomer* _zoomer;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QwtPlot* plot = new Plot;

    plot->setEnabled(false);

    plot->show();

    return a.exec();
}

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[freshairfly]

Thanks your share.
Because the zoomer/picker is not always enabled in my case,
I must remember the picker/zoomer's state (named oldState) before the plot changes to disabled. Then the plot is enabled, the zoomer should be set to the oldState.