public void mousePressed(MouseEvent event) {
            Point2D pontoTela = event.getPoint();
            double larg = 100;
            double alt = 20;
            double cx = pontoTela.getX() - larg / 2.0;
            double cy = pontoTela.getY() - alt / 2.0;
            Retangulo retangulo = new Retangulo(cx, cy, larg, alt);
            objetos.add(retangulo);
            repaint();
        }