Fixed interactive save to use rcParams for facecolor and edgecolor.

[u55]

Fix for issue #3437. I implemented the rcParams for 'savefig.facecolor' and 'savefig.edgecolor', but I did not try to implement the 'savefig.transparent' option. This is only a temporary fix, as the savefig logic is currently duplicated in multiple places and should be refactored.

[tacaswell]

Can you also change around L1504 to default to passing None in to print_figure so we only have the rcparam look-up logic once?

[u55]

@tacaswell, you must mean approximately line 1504 of figure.py rather than backend_bases.py. I wonder if everything from figure.py/Figure.savefig should be moved to backend_bases.py/FigureCanvasBase.print_figure, with the exception of the call to self.canvas.print_figure(*args, **kwargs) of course. What do you think?

Also, according to the CHANGELOG from 2007-09-06, backend canvases are not supposed to override the print_figure method, so it does seem safe to move everything to this method.

Alternatively, it seems that everything could be moved from backend_bases.py/FigureCanvasBase.print_figure to figure.py/Figure.savefig if all of the interactive backends were to change their NagivationToolbar2 classes to use something like: self.canvas.figure.savefig(six.text_type(fname)) instead of self.canvas.print_figure(six.text_type(fname)), in their overridden save_figure method. However, there are a few documented examples that use the canvas.print_figure method explicitly, such as examples/pylab_examples/hyperlinks.py, and I wonder if these are just really old examples or if there is still a use case for fig.canvas.print_figure instead of fig.savefig?

[tacaswell]

Yes, I did mean in figure.py, sorry for being unclear.

This does bring up a discussion of where the rcparam logic should be looked up and I do not have a clear answer for that off the top of my head.

The toolbar just got a major overhaul. attn @OceanWolf

I think I am on board with changing all of those calls to 'print_figure->self.canvas.fig.save_fig()`, but that is some what orthogonal to where the default logic goes.

[OceanWolf]

@tacaswell do you mean MEP22? sounds like a good idea to me. I do have plans to do more savefig overhaul as part of MEP22 as and when I get around to it (thesis, job interviews, etcetera, hopefully by this weekend)

[u55]

Yes, I guess the question is: As a general rule, should rcParams be handled as early as possible or as late as possible? I would expect that earlier is better.

I could remove the kwarg-passing lines near L1504 of figure.py, for this pull request, as you suggested @tacaswell. But I currently do not have time right now to any significant code refactoring and testing. If someone else, such as @OceanWolf, wants to do a more extensive fix, then I am happy to abandon this PR.

[OceanWolf]

To clarify, by overhaul, I just mean moving out the backend specific savefig to backend.tools, we only need a mechanism to get a filename from the backend which a generic savefig method would call (GTK3 already has this logic split, it just needs a copy-paste to backend-tools and then get expanded on with the other backends, probably with a tidy-up at the same time as it looks a bit messy 😉).

So yes, @u55 my concern only lies with a first pass to clear the specific backends of generic functionality, moving to backend_tools.

[tacaswell]

@u55 Any progress on this?

I am re-milestoning this to 'proposed next point release'. If it is ready it can go in, but it will not be a blocker for the next point release.

[QuLogic]

Replaced by #6197.