Unexpected error after using Figure.canvas.draw on macosx backend #19197
Description
Bug report
Bug summary
It has been claimed that "fig.canvas.draw() is the canonical way to trigger a draw", replacing fig.draw(fig.canvas.get_renderer()). But on the macosx backend, this seems not to work.
Code for reproduction
import matplotlib.pyplot as plt
f, ax = plt.subplots()
lines = ax.plot([0, 1])
legend = ax.legend(lines, ["a line"])
f.canvas.draw()
# f.draw(f.canvas.get_renderer())
print(legend.get_window_extent())Actual outcome
Traceback (most recent call last):
File "mpl_issue.py", line 7, in <module>
print(legend.get_window_extent())
File "/Users/mwaskom/miniconda3/lib/python3.7/site-packages/matplotlib/legend.py", line 897, in get_window_extent
return self._legend_box.get_window_extent(renderer=renderer)
File "/Users/mwaskom/miniconda3/lib/python3.7/site-packages/matplotlib/offsetbox.py", line 346, in get_window_extent
w, h, xd, yd, offsets = self.get_extent_offsets(renderer)
File "/Users/mwaskom/miniconda3/lib/python3.7/site-packages/matplotlib/offsetbox.py", line 462, in get_extent_offsets
dpicor = renderer.points_to_pixels(1.)
AttributeError: 'NoneType' object has no attribute 'points_to_pixels'Expected outcome
On the qt5agg backend, or when uncommenting the (deprecated?) f.draw(f.canvas.get_renderer()) line, the code runs and prints the extent of the legend.
Matplotlib version
- Operating system: Macos
- Matplotlib version: 3.3.3
- Matplotlib backend (
print(matplotlib.get_backend())): macosx - Python version: 3.8
- Jupyter version (if applicable): na
- Other libraries:
xref #18407, mwaskom/seaborn#2399