"""
====================
Auto Subplots Adjust
====================

Automatically adjust subplot parameters. This example shows a way to determine
a subplot parameter from the extent of the ticklabels using a callback on the
:doc:`draw_event</users/event_handling>`.

Note that a similar result would be achieved using `~.Figure.tight_layout`
or `~.Figure.set_constrained_layout`; this example shows how one could
customize the subplot parameter adjustment.
"""

import matplotlib.pyplot as plt
import matplotlib.transforms as mtransforms

fig, ax = plt.subplots()
ax.plot(range(10))
ax.set_yticks((2, 5, 7))
labels = ax.set_yticklabels(('really, really, really', 'long', 'labels'))

def on_draw(event):
    bboxes = []
    for label in labels:
        bbox = label.get_window_extent()
        # the figure transform goes from relative coords->pixels and we
        # want the inverse of that
        bboxi = bbox.transformed(fig.transFigure.inverted())
        bboxes.append(bboxi)
    # the bbox that bounds all the bboxes, again in relative figure coords
    bbox = mtransforms.Bbox.union(bboxes)
    if fig.subplotpars.left < bbox.width:
        # we need to move it over
        fig.subplots_adjust(left=1.1*bbox.width)  # pad a little
        fig.canvas.draw()

fig.canvas.mpl_connect('draw_event', on_draw)

plt.show()

#############################################################################
#
# ------------
#
# References
# """"""""""
#
# The use of the following functions, methods, classes and modules is shown
# in this example:

import matplotlib
matplotlib.artist.Artist.get_window_extent
matplotlib.transforms.Bbox
matplotlib.transforms.Bbox.transformed
matplotlib.transforms.Bbox.union
matplotlib.transforms.Transform.inverted
matplotlib.figure.Figure.subplots_adjust
matplotlib.figure.SubplotParams
matplotlib.backend_bases.FigureCanvasBase.mpl_connect