Sorting QPolygonF

[giusepped]

there is a way to sort a QPolygonF, for example, by considering
the x value?
Regards

[aamer4yu]

May be you can put the polygons in QList. Then use qSort .
You can provide your own lessThan function in the qSort. See docs for more info

[giusepped]

I tried with the following code

bool MyPlot::lessThanPoint(const QPointF &p1, const QPointF &p2)
{
	return ( p1.x() < p2.x() );
 
}
QPolygonF   MyPlot::combine(const QPolygonF &p1, const QPolygonF &p2)
{
 
 
 
 
	QPolygonF un(p1.united(p2));
	qSort(un.begin(),un.end(),lessThanPoint);
	return un;
}

bool MyPlot::lessThanPoint(const QPointF &p1, const QPointF &p2)
{
	return ( p1.x() < p2.x() );
			
}
QPolygonF   MyPlot::combine(const QPolygonF &p1, const QPolygonF &p2)
{
	
	 

	
	QPolygonF un(p1.united(p2));
	qSort(un.begin(),un.end(),lessThanPoint);
	return un;
}

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but I get

myplot.cpp:943: error: no matching function for call to ‘qSort(QPointF*, QPointF*, <unresolved overloaded function type>)’
/usr/local/Trolltech/Qt-4.4.0/include/QtCore/qalgorithms.h:203: note: candidates are: void qSort(RandomAccessIterator, RandomAccessIterator, LessThan) [with RandomAccessIterator = QPointF*, LessThan = bool (MyPlot::*)(const QPointF&, const QPointF&)]

[caduel]

You can't use member functions for such functors.

You have to make that lessThanPoint either
* static (in your class)
* static (in your file; remove from class header then)
* turn it into a functor (i.e. a real class; or by means like boost::bind)

HTH