Russian Qt Forum

void ItemSnake::paintEvent(QPaintEvent *)
{
    RenderMode(direction);
}

void ItemSnake::RenderMode(Direction dir)
{
    QPainter painter(this);

    painter.setPen(QPen(Qt::green,2,Qt::SolidLine));

    if(dir == CommonDate::Down || dir == CommonDate::Up) {
        painter.drawLine(x() - offest, y() - offest, x() - offest, y() + offest);
        painter.drawLine(x() + offest, y() - offest, x() + offest, y() + offest);
        //painter.setBackground(QBrush(Qt::green));
        painter.setBrush(Qt::green);
//        QPalette pal;
//        pal.setColor(this->backgroundRole(), Qt::green);

//        this->setPalette(pal);
//        this->setAutoFillBackground(true);
//        qDebug() << scene.sceneRect();
    }

    if(dir == CommonDate::Right || dir == CommonDate::Left) {
        painter.drawLine(x() - offest, y() - offest, x() + offest, y() - offest);
        painter.drawLine(x() - offest, y() + offest, x() + offest, y() + offest);
        painter.setBackground(QBrush(Qt::green));
    }
    switch (dir) {
        case CommonDate::TurnLeftUp :
          QPolygon poly;
          poly << QPoint(10,10) << QPoint(40,40) << QPoint(10,30) << QPoint(20,10);
          painter.setBrush(Qt::red);
          painter.drawPolygon(poly);
          break;
        default:
            //throw UnknownDirection;
            break;
    }
}

Объявление: 
class ItemSnake : public QWidget, public CommonDate
{
    Q_OBJECT
public:
    explicit ItemSnake(QGraphicsScene& scene, CommonDate::Direction dir);
private:
    CommonDate::Direction direction; //direction snake
    const int offest;
    QGraphicsScene& scene;
protected:
    void RenderMode(CommonDate::Direction dir); //render item on the mode
    void paintEvent(QPaintEvent*);
};

class CommonDate //class, showing the direction of movement ItemSnake
{
protected:
    enum Direction
    {
        Right,
        Left,
        Up,
        Down,
        TurnRightUp,
        TurnLeftUp,
        TurnRightDown,
        TurnLeftDown,
        RightHead,
        LeftHead,
        UpHead,
        DownHead
    };
};