Inheritance and QpaintEvent

[djoul]

Why do you create new widgets if Son is a widget too? Wouldn't it be enough to redraw Son?

But I don t want to create new ones ! Qt does ...
The architecture is :
I've got a class Bck1 and Bck2. In both classes I do some drawing with QPaintEvent (the 2 classes are Widgets).
I ve got then the class Mother with his Son.
And I want the Son to do some drawings in bot he Bck1 and Bck2.
My problem is : Son is not a Widget but he must inherit from QWidget to know where he must paint ?

#include <QWidget>
 
class Bck1: public QWidget
{
	Q_OBJECT
 
	public : 
		Bck1(QWidget *parent = 0);	
		~Bck2();
		...	
	protected :
		void paintEvent(QPaintEvent *event);	
		void mousePressEvent(QMouseEvent *event);
		void keyPressEvent(QKeyEvent *event);
...}
 
#include <QWidget>
 
class Bck2: public QWidget
{
	Q_OBJECT
 
	public : 
		Bck2(QWidget *parent = 0);	
		~Bck2();
 
	protected :
		void paintEvent(QPaintEvent *event);	
}
 
 
#include <QWidget>
 
 
class Mother: public QWidget 
{
	Q_OBJECT
 
	public :
		Mother(QWidget *parent=0);
		virtual ~Mother();	
	protected :
		virtual void paintEvent(QPaintEvent *event)=0;
 
 
};
 
#include <QWidget>
 
class Son : public Mother
{
 
	Q_OBJECT
 
	public : 
		Son(.....);//do I need to put Son(QWidget *parent=0) ... ?????
		 ~Son();
 
	protected :
		  void paintEvent(QPaintEvent *event);
}

#include <QWidget>

class Bck1: public QWidget
{
	Q_OBJECT

	public : 
		Bck1(QWidget *parent = 0);	
		~Bck2();
		...	
	protected :
		void paintEvent(QPaintEvent *event);	
		void mousePressEvent(QMouseEvent *event);
		void keyPressEvent(QKeyEvent *event);
...}

#include <QWidget>

class Bck2: public QWidget
{
	Q_OBJECT

	public : 
		Bck2(QWidget *parent = 0);	
		~Bck2();

	protected :
		void paintEvent(QPaintEvent *event);	
}


#include <QWidget>


class Mother: public QWidget 
{
	Q_OBJECT

	public :
		Mother(QWidget *parent=0);
		virtual ~Mother();	
	protected :
		virtual void paintEvent(QPaintEvent *event)=0;
	

};

#include <QWidget>

class Son : public Mother
{

	Q_OBJECT

	public : 
		Son(.....);//do I need to put Son(QWidget *parent=0) ... ?????
		 ~Son();

	protected :
		  void paintEvent(QPaintEvent *event);
}

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Does it seems ok ? I never know if I need to specify *parent or *parent=0, and if I need to put Qwidget *parent in the Son constructor ???