[SOLVED] Creating custom QLineF

alogim

Hello, I need to create a custom QLineF, called MyQLineF. However, I've got some problems. Here's the code:
myqlinef.h

#ifndef MYQLINEF_H
#define MYQLINEF_H
#include <QLineF>
#include "node.h"
#include <myqpointf.h>

class MyQLineF : public QLineF
{
public:
	MyQLineF(QPointF p1, QPointF p2);
	MyQLineF(node n1, node n2);
	node n1();
	node n2();
	void setN1(node n);
	void setN2(node n);

private:
	node src, dst;
};

#endif // MYQLINEF_H

MyQLineF.cpp

#include "myqlinef.h"

MyQLineF::MyQLineF(QPointF p1, QPointF p2)
{
  this->setLine(p1.x(), p1.y(), p2.x(), p2.y());
  node n1, n2;
  n1.x = p1.x();
  n2.x = p2.x();
  n1.y = p1.y();
  n2.y = p2.y();
  setN1(n1);
  setN2(n2);
}

MyQLineF::MyQLineF(node n1, node n2)
{
  this->setLine(n1.x, n1.y, n2.x, n2.y);
  setN1(n1);
  setN2(n2);
}

node MyQLineF::n1()
{
  return this->src;
}

node MyQLineF::n2()
{
  return this->dst;
}

void MyQLineF::setN1(node n)
{
  this->src = n;
}

void MyQLineF::setN2(node n)
{
  this->dst = n;
}

node.h:

#ifndef NODE_H
#define NODE_H

typedef enum {START, TARGET} type;

typedef struct node
{
  int x;
  int y;
  int id;
  type belongsTo;
} node;

#endif // NODE_H

All goes well until I try to create a QVector<MyQLineF>.
The following problems occur:

In file included from /usr/include/qt/QtGui/qbrush.h:39:0,
             from /usr/include/qt/QtGui/qpalette.h:39,
             from /usr/include/qt/QtWidgets/qwidget.h:41,
             from /usr/include/qt/QtWidgets/qmainwindow.h:37,
             from /usr/include/qt/QtWidgets/QMainWindow:1,
             from ../MyQPointF/mainwindow.h:4,
             from ../MyQPointF/mainwindow.cpp:1:
/usr/include/qt/QtCore/qvector.h: In instantiation of 'void QVector<T>::defaultConstruct(T*, T*) [with T = MyQLineF]':
/usr/include/qt/QtCore/qvector.h:537:41:   required from 'void QVector<T>::reallocData(int, int, QArrayData::AllocationOptions) [with T = MyQLineF; QArrayData::AllocationOptions = QFlags<QArrayData::AllocationOption>]'
/usr/include/qt/QtCore/qvector.h:607:20:   required from 'void QVector<T>::append(const T&) [with T = MyQLineF]'
/usr/include/qt/QtCore/qvector.h:225:47:   required from 'void QVector<T>::push_back(const T&) [with T = MyQLineF]'
../MyQPointF/mainwindow.cpp:56:15:   required from here
/usr/include/qt/QtCore/qvector.h:284:13: error: no matching function for call to 'MyQLineF::MyQLineF()'
         new (from++) T();
         ^
In file included from ../MyQPointF/mainwindow.h:6:0,
             from ../MyQPointF/mainwindow.cpp:1:
../MyQPointF/myqlinef.h:12:3: note: candidate: MyQLineF::MyQLineF(node, node)
   MyQLineF(node n1, node n2);
   ^
../MyQPointF/myqlinef.h:12:3: note:   candidate expects 2 arguments, 0 provided
../MyQPointF/myqlinef.h:11:3: note: candidate: MyQLineF::MyQLineF(QPointF, QPointF)
 MyQLineF(QPointF p1, QPointF p2);
 ^
../MyQPointF/myqlinef.h:11:3: note:   candidate expects 2 arguments, 0 provided
../MyQPointF/myqlinef.h:8:7: note: candidate: MyQLineF::MyQLineF(const MyQLineF&)
 class MyQLineF : public QLineF
       ^
../MyQPointF/myqlinef.h:8:7: note:   candidate expects 1 argument, 0 provided

Why does this happen? Should I override each constructor in the QLineF class?
Note: using std::vector instead of QVector solves this i ssue, but I'm curious about this problem.

SGaist

Hi,

That's because your class doesn't have a default constructor. You can find more information on the The Container Classes chapter of Qt's documentation.

alogim

Thank you @SGaist . So, is it enough to add

MyQLineF() {}

as it is described in that page?

SGaist

It should be yes