Undefined interface Q_INTERFACES(QGraphicsItem)

Massi

Hello Qt forum

I have created a vs2012 dll project which uses Qt library on windows platform. I have a QgraphicView that hold elements (widgets) and perform some animation with them. However I want to use Q_INTERFACES macro in on of my classes that inherits from QgraphicsItem but I get the following error:

error : Undefined interface

How can I define this macro and where to define it in my project?

Thanks in advance!

Massi

sierdzio

Can you provide some more info, preferably some code sample?

Some general info is in the docs: link and link.

dheerendra

QGraphicsItem is not interface. I'm assuming that you are developing a plugin. You can look at the Qt Assistant for "How to create Qt plugin". You can look for topics "The Low-Level API: Extending Qt Applications". It start with defining your own interface and implementing this interface.

Massi

Many thanks for your quick reply!

Well, I'm refactoring a Qt mingw code to Qt visual studio 2012. I have a C++.net dll project and I'm using Qt to display graphics widget. I'm not familiar with Q_INTERFACES macro and I'm not creating a Qt plugin either. Basically, I just have a class that inherit from QGraphicItems and QObject class. Since I'm using vs2012 and I had to handle moc file manually, I'm wondering if it might be the source cause of my issue?

class SupperClass : public QObject, public QGraphicsItem
{
       Q_OBJECT
       Q_INTERFACES(QGraphicsItem)
public:
  	// Animation function (from graphics item)
	void advance(int p_step);
private:
        // members
}
class GraphicsView : public QGraphicsView
{
      Q_OBJECT
public:
      GraphicsView() {
         m_timer = new QTimer(this);
	 connect(m_timer, SIGNAL(timeout()), m_scene, SLOT(advance()));
       }
private:
      QTimer * m_timer;
}

Again thanks for your time and help!!

Massi

SGaist

Hi,

There's no need for that combo, Qt provides QGraphicsObject. And like @dheerendra wrote already, Q_INTERFACES only makes sense in a plugin project.

Massi

@SGaist Many thanks for the info!!!