>>> """
========================
Custom Figure subclasses
========================

You can pass a `.Figure` subclass to `.pyplot.figure` if you want to change
the default behavior of the figure.

This example defines a `.Figure` subclass ``WatermarkFigure`` that accepts an
additional parameter ``watermark`` to display a custom watermark text. The
figure is created using the ``FigureClass`` parameter of `.pyplot.figure`.
The additional ``watermark`` parameter is passed on to the subclass
constructor.
"""
... 
... import matplotlib.pyplot as plt
... from matplotlib.figure import Figure
... import numpy as np
... 
... 
... class WatermarkFigure(Figure):
...     """A figure with a text watermark."""
... 
...     def __init__(self, *args, watermark=None, **kwargs):
...         super().__init__(*args, **kwargs)
... 
...         if watermark is not None:
...             bbox = dict(boxstyle='square', lw=3, ec='gray',
...                         fc=(0.9, 0.9, .9, .5), alpha=0.5)
...             self.text(0.5, 0.5, watermark,
...                       ha='center', va='center', rotation=30,
...                       fontsize=40, color='gray', alpha=0.5, bbox=bbox)
... 
... 
... x = np.linspace(-3, 3, 201)
... y = np.tanh(x) + 0.1 * np.cos(5 * x)
... 
... plt.figure(FigureClass=WatermarkFigure, watermark='draft')
... plt.plot(x, y)
... 
... 
... #############################################################################
... #
... # .. admonition:: References
... #
... #    The use of the following functions, methods, classes and modules is shown
... #    in this example:
... #
... #    - `matplotlib.pyplot.figure`
... #    - `matplotlib.figure.Figure`
... #    - `matplotlib.figure.Figure.text`
...