get default margins

def get_default_margins(self):
        """get default margins"""
        trans = self.fig.transFigure.inverted().transform

        # Static margins
        l, t, r, b = self.axesmargins
        (l, b), (r, t) = trans(((l, b), (r, t)))

        # Extent
        dl, dt, dr, db = 0, 0, 0, 0
        for i, ax in enumerate(self.fig.get_axes()):
            (x0, y0),(x1, y1) = ax.get_position().get_points()
            try:
                (ox0, oy0), (ox1, oy1) = ax.get_tightbbox(self.canvas.get_renderer()).get_points()
                (ox0, oy0), (ox1, oy1) = trans(((ox0 ,oy0),(ox1 ,oy1)))
                dl = min(0.2, max(dl, (x0 - ox0)))
                dt = min(0.2, max(dt, (oy1 - y1)))
                dr = min(0.2, max(dr, (ox1 - x1)))
                db = min(0.2, max(db, (y0 - oy0)))
            except:
                pass

        return (l + dl, t + dt, r + dr, b + db)