I've expanded a bit on my previous solution for pre/post draw method
callbacks to add a registry which can be used to connect up arbitrary
callback functions.
The solution above is easy to adapt to other functions that might need
a callback, such as (to pick a random example) set_xlim.
See the attached example, which shows the functionality in action.
I've also shown how to handle the calls to start/stop raster in the
renderer that were my previous use case.
-Eric B
from matplotlib.cbook import CallbackRegistry
from matplotlib.axes import Axes
class Hooks(object):
def __init__(self):
signals = ('before_draw', 'after_draw')
self.callbacks = CallbackRegistry(signals)
def before_after_draw(self, draw):
"""
Decorator for Artist.draw method. Provides routines
that run before and after the draw call. The before and after functions
are useful for changing artist-dependant renderer attributes or making
other setup function calls, such as starting and flushing a mixed-mode
renderer.
"""
def before(artist, renderer):
self.callbacks.process('before_draw', artist, renderer)
def after(artist, renderer):
self.callbacks.process('after_draw', artist, renderer)
def draw_wrapper(artist, renderer):
before(artist, renderer)
draw(artist, renderer)
after(artist, renderer)
# "safe wrapping" to exactly replicate anything we haven't overridden above
draw_wrapper.__name__ = draw.__name__
draw_wrapper.__dict__ = draw.__dict__
draw_wrapper.__doc__ = draw.__doc__
return draw_wrapper
def greeter(artist, renderer):
print 'Hello, ', artist, '. You will be rendered tonight by', renderer
def benediction(artist, renderer):
print 'Good night, ', artist, '. You were rendered tonight by', renderer
def start_raster_mode(artist, renderer):
if artist.get_rasterized():
renderer.start_rasterizing()
def stop_raster_mode(artist, renderer):
if artist.get_rasterized():
renderer.stop_rasterizing()
hooks = Hooks()
hooks.callbacks.connect('before_draw', greeter)
hooks.callbacks.connect('after_draw', benediction)
hooks.callbacks.connect('before_draw', start_raster_mode)
hooks.callbacks.connect('after_draw', stop_raster_mode)
class WrappedAxes(Axes):
""" In real life, the Axes.draw() method would be decorated directly,
but this serves for the purposes of this demo. """
@hooks.before_after_draw
def draw(self, renderer):
super(WrappedAxes, self).draw(renderer)
import matplotlib.pyplot as plt
fig = plt.figure()
fig.clf()
ax = fig.add_axes(WrappedAxes(fig, (0.1,0.1,0.8,0.8)))
ax.plot(range(10))
plt.show()
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