Attach a FigureCanvasBase by default to Figures. #12450
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First thought: Does this involve any costly setup logic? We are already quite slow in creating figures. Second thought: Is just for semantic reasons? Third thought: Do we now get more strange behavior or error message when we try things that would before fail due to the missing canvas? |
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No just looked at the code 😄
Doesn't sound well thought through. I haven't either, but I'm hesitant to introduce a code change with an effect that we do not overlook. |
I actually really think it's not going to cause any problems, but as usual things are tied up in so many knots in mpl that it's hard to know if we don't try. |
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| "rotation disabled. Set canvas then call " | ||
| "Axes3D.mouse_init().") | ||
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| self._cids = [ |
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Concerned that if we are hitting this code path with the base canvas and then it gets replaced the subscriptions will not work.
On the other hand, you are no worse than you are now.
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So I'll leave it as it is until someone complains :)
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This code was last touched in b0807ae which was primarily reverting #1125 The original I suspect looking at why #1125 failed would be a good guide to if we are missing something here. From a very quick look, that PR defaulted to getting the current backend from pyplot (more-or-less) where as this is is going with the base class which has just enough logic to fall-back on save. Another option is to make |
This is particularly useful for headless cases, where one just wants to
take advantage of `print_figure`, which is defined on the base class.
For example, one can now do
for <loop>:
figure = Figure()
# do some plotting
figure.savefig(...)
and let `figure` get gc'd at the next loop iteration; a pyplot-based
solution would instead have to explicitly close() the figure or reuse it
after clf()'ing it.
Also simplifies various places in the codebase where we had to handle
the case of `.canvas = None` previously.
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Looking at #1457 (comment) it looks like #1125 failed because not all Canvas classes have the same constructor signature, but that's not a problem here. In both cases I think using FigureCanvasBase avoids these problems. |
In 380c531 / matplotlib#12450 we set the default canvas on Figure `__init__` to FigureCanvasBase but were still setting it to `None` in `__setstate__`.
In 380c531 / matplotlib#12450 we set the default canvas on Figure `__init__` to FigureCanvasBase but were still setting it to `None` in `__setstate__`.
This is particularly useful for headless cases, where one just wants to
take advantage of
print_figure, which is defined on the base class.For example, one can now do
and let
figureget gc'd at the next loop iteration; a pyplot-basedsolution would instead have to explicitly close() the figure or reuse it
after clf()'ing it.
Also simplifies various places in the codebase where we had to handle
the case of
.canvas = Nonepreviously.xref #11657, #12447.
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