problem with painting one widget inside another one (parent)

I am trying to make a simple game under Qt 4.6. The idea is to have two widgets, one is the main window widget and represents the space and the second one is a starship widget inside the space (parent). Simplified code looks like this:

/*this is ship and child widget*/
class MyRect : public QWidget {

Q_OBJECT

public:
MyRect(QWidget* parent)
    : QWidget(parent)
{
    itsParent = parent;

    itsx = 120;
    itsy = 250;
    itsw = 110;
    itsh = 35;
    body = new QRect(itsx, itsy, itsw, itsh);

}

~MyRect() {}


protected:
    void paintEvent(QPaintEvent *event);

private:
int itsx;
int itsy;
int itsw;
int itsh;
QRect* body;
QWidget* itsParent;

};


void MyRect::paintEvent(QPaintEvent *event)
{

  QPen pen(Qt::black, 2, Qt::SolidLine);
  QColor hourColor(0, 255, 0);


  QPainter painter(itsParent);

  painter.setBrush(hourColor);  
  painter.setPen(pen);
  painter.drawRect(*body);

}


/*this is space and main window widget*/
class space : public QMainWindow
{
  Q_OBJECT

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

protected:


private:
   MyRect* ship;

};

space::space(QWidget *parent)
 : QMainWindow(parent)
{
   ship = new MyRect(this);
}

When I compile, the screen is blank and rectangle MyRect::body is not drawn. I checked the Qt online documentation and did some google research with no luck. Any explanation about this is welcome. I want to draw one widget on anothe开发者_JAVA百科r (parent).

• QPainter painter(itsParent); - wrong. You should draw only on this widget's surface, not on parents. So correct will be QPainter painter(this);
• You should not save widgets body in MyRect class. Class space must keep its size and position. So in MyRect::paintEvent() change painter.drawRect(*body); to painter.drawRect( rect() );
• So class MyRect should have no members at all.
• Last thing remained: in space::space() add
ship->move( 120, 250 );
ship->resize( 110, 35 );
QPalette pal = palette();
pal.setColor( QPalette::Background, Qt::black ); // space is black, isn't it?
setPalette( pal );
resize( 500, 500 );

and voila.