Subclass QGraphicsView issues [SOLVED]

[justinflowers]

Hey guys,

Been trying to subclass QGraphicsView to add a keystroke listener. I'm getting an undefined reference when I call the constructor for my view with a scene. How do I properly define the constructor for a subclassed QGraphicsView taking in a scene such that it handles it in the exact same way a regular QGraphicsView would?

Line in main I'm getting the error:
@
PieguyView view(&scene);
// before I was using QGraphicsView view(&scene);
@

pieguyview.h:
@
#ifndef PIEGUYVIEW_H
#define PIEGUYVIEW_H

#include <QGraphicsView>
#include<QKeyEvent>
class PieguyView : public QGraphicsView
{
Q_OBJECT
public:
explicit PieguyView(QObject *parent = 0);

protected:
void keyPressEvent ( QKeyEvent * event );
signals:

public slots:

};

#endif // PIEGUYVIEW_H
@

pieguyview.cpp:
@
#include "pieguyview.h"
#include<QDebug>

void PieguyView::keyPressEvent ( QKeyEvent * event ){

switch ( event->key())
{
    case Qt::Key_Up:
        qDebug() << "Up";
        break;
}

QGraphicsView::keyPressEvent(event);

}
@

exact error:
@
C:\Users\Justin\pieguy\main.cpp:26: error: undefined reference to `PieguyView::PieguyView(QObject*)'--
@

[andreyc EDIT]: Added @ around code.

[andreyc]

QGraphicsView constructor that you were using is defined like this
@
QGraphicsView::QGraphicsView(QGraphicsScene * scene, QWidget * parent = 0)
@

So you need to define the same constructor for your class

• header file
  @
  ...
  PieguyView(QGraphicsScene * scene, QObject *parent = 0);
  ...
  @

• source file
  @
  ...
  PieguyView::PieguyView(QGraphicsScene * scene, QObject *parent)
  : QGraphicsView(scene, parent)
  ...
  @

[justinflowers]

Thanks for the reply!
Tried that and getting a new error:
@
C:\Users\Justin\pieguy\pieguyview.cpp:18: error: invalid conversion from 'QObject*' to 'QWidget*' [-fpermissive]
: QGraphicsView(scene, parent){
^
@

pieguyview.h:
@
#ifndef PIEGUYVIEW_H
#define PIEGUYVIEW_H

#include <QGraphicsView>
#include<QKeyEvent>
class PieguyView : public QGraphicsView
{
public:
PieguyView(QGraphicsScene * scene, QObject *parent = 0);

protected:
void keyPressEvent ( QKeyEvent * event );
signals:

public slots:

};

#endif // PIEGUYVIEW_H
@

pieguyview.cpp:
@
#include "pieguyview.h"
#include<QDebug>

void PieguyView::keyPressEvent ( QKeyEvent * event ){

switch ( event->key())
{
    case Qt::Key_Up:
        qDebug() << "Up";
        break;
}

QGraphicsView::keyPressEvent(event);

}

PieguyView::PieguyView(QGraphicsScene * scene, QObject *parent)
: QGraphicsView(scene, parent){

}
@

[andreyc EDIT]: Added '@' around code. Please use @ to highlight the code

[andreyc]

Please use '@' to highlight the code.

About the error. I copy-pasted part of your definition and did not verify that it was a QObject and not a QWidget.
Correct declaration and definition should be

• header file
  @
  ...
  PieguyView(QGraphicsScene * scene, QWidget *parent = 0);
  ...
  @

• source file
  @
  ...
  PieguyView::PieguyView(QGraphicsScene * scene, QWidget *parent)
  : QGraphicsView(scene, parent)
  ...
  @

[justinflowers]

Thank you so much!
And many apologies for missing the @s, will do in the future haha.

[andreyc]

Glad that it works for you.
Please add [SOLVED] to the title of your original post. It will help other people to find a possible solution.