[Matplotlib-devel] Confusion about draw_artist

[Matthew Brett]

Hi,

We're using 'draw_artist' in an image viewer, and I just found that
our viewer is crashing using the macosx backend.  Here's a minimal
example:

import matplotlib
matplotlib.use('macosx')
import matplotlib.pyplot as plt

fig, ax = plt.subplots(1, 1)
im = plt.imshow([[1, 2], [3, 4]])
fig.canvas.draw()
ax.draw_artist(im)

This generates:

Traceback (most recent call last):
  File "draw_artist.py", line 8, in <module>
    ax.draw_artist(im)
  File "/Users/mb312/dev_trees/matplotlib/lib/matplotlib/axes/_base.py",
line 2423, in draw_artist
    raise AttributeError(msg)
AttributeError: draw_artist can only be used after an initial draw
which caches the render

for the macosx backend, and works correctly for the tkagg backend.

I can't see any way to cache the renderer here - could someone give me
a pointer?

Cheers,

Matthew