Draws the axis for the given painter.
        
        :param      painter | <QPainter>
                    rect    | <QRect>

def drawAxis(self, painter, rect, axis):
        """
        Draws the axis for the given painter.
        
        :param      painter | <QPainter>
                    rect    | <QRect>
        """
        if not axis:
            return
        
        # draw the axis lines
        painter.save()
        pen = QPen(self.axisColor())
        pen.setWidth(3)
        painter.setPen(pen)
        
        # draw the vertical line
        if axis.orientation() == Qt.Vertical:
            line = QLineF(rect.right(), rect.top(),
                          rect.right(), rect.bottom())
            
            painter.drawLine(line)
            painter.setFont(axis.labelFont())
            for y, height, label in self._buildData.get('grid_h_labels', []):
                painter.drawText(0, y - height / 2.0, rect.width() - 3, height,
                                 Qt.AlignRight | Qt.AlignVCenter, label)
            
            painter.translate(0, rect.center().y())
            painter.rotate(-90)
            
            painter.setFont(axis.titleFont())
            painter.drawText(-rect.height()/2, 0, rect.height(), rect.width(),
                             Qt.AlignHCenter | Qt.AlignTop, axis.title())
            
        # draw the horizontal line
        else:
            line = QLineF(rect.left(), rect.top(),
                          rect.right(), rect.top())
            
            painter.setFont(axis.titleFont())
            painter.drawText(rect,
                             Qt.AlignHCenter | Qt.AlignBottom,
                             axis.title())
            
            painter.drawLine(line)
            painter.setFont(axis.labelFont())
            for x, width, label in self._buildData.get('grid_v_labels', []):
                painter.drawText(x - width / 2.0, 3, width, rect.height() - 6,
                                 Qt.AlignHCenter | Qt.AlignTop, label)
        painter.restore()