change the painter of parent.

[weixj2003ld]

I draw a polygon int the paintEvent of class A,and create class B based on A.

Now I want to fill the polygon of A in the paintEvent of B,how to do?

[wysota]

Provide a virtual method in A that is called during paint event of A and reimplement that method in B.

[weixj2003ld]

Thk u for your answer.But My problem is still exists.
Now I paste my code on the page,

class A :public QLabel
//.h
{
    Public
     A(QWidget *parent=0);
    void virtual paintEvent(QPaintEvent *);
};
class B:public A
{
    public 
     B(QWidget *parent=0);
    void  paintEvent(QPaintEvent *)
};
 
/*.cpp*/
 
A::A();
void A::paintEvent(QPaintEvent *)
{
    /*Here,Draw a Polygon,but not filled.*/
}
B::B(QWidget *parent):A(parent)
{
}
void B::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
   painter.SetBrush(Qt::BrushStyle::SolidPattern);
   A::paintEvent(e);
}

class A :public QLabel
//.h
{
    Public
     A(QWidget *parent=0);
    void virtual paintEvent(QPaintEvent *);
};
class B:public A
{
    public 
     B(QWidget *parent=0);
    void  paintEvent(QPaintEvent *)
};

/*.cpp*/

A::A();
void A::paintEvent(QPaintEvent *)
{
    /*Here,Draw a Polygon,but not filled.*/
}
B::B(QWidget *parent):A(parent)
{
}
void B::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
   painter.SetBrush(Qt::BrushStyle::SolidPattern);
   A::paintEvent(e);
}

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Why?

[wysota]

Why what? This is not what I told you to do...

class A :public QLabel
//.h
{
public:
     A(QWidget *parent=0);
protected:
    void virtual paintEvent(QPaintEvent *);
    virtual void setupPainter(QPainter*) {}
};
 
class B:public A
{
    public: 
     B(QWidget *parent=0);
protected:
  void setupPainter(QPainter *p) {
    p->setBrush(...);
  }
};
 
/*.cpp*/
 
A::A();
void A::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    setupPainter(&p);
    p.draw....
}
B::B(QWidget *parent):A(parent)
{
}

class A :public QLabel
//.h
{
public:
     A(QWidget *parent=0);
protected:
    void virtual paintEvent(QPaintEvent *);
    virtual void setupPainter(QPainter*) {}
};

class B:public A
{
    public: 
     B(QWidget *parent=0);
protected:
  void setupPainter(QPainter *p) {
    p->setBrush(...);
  }
};

/*.cpp*/

A::A();
void A::paintEvent(QPaintEvent *)
{
    QPainter p(this);
    setupPainter(&p);
    p.draw....
}
B::B(QWidget *parent):A(parent)
{
}

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