Tick vertical alignment

[mdboom]

Fixes #2527. Align y-ticks without accounting for descenders

[tacaswell]

Seems to have broken all of the pgf tests.

That makes me a bit worried about other backends that we do not control....

[mdboom]

Sorry -- I have a new box and I think I don't have all the pgf reqs installed yet. I can probably regenerate those.

As for other backends we don't control, I think we'll just be seeing better tick text alignment in all of them -- this approach is delibrately rather narrow and shouldn't affect other kinds of text. But, yes, we will be breaking those other backends image comparison tests, if any.

[tacaswell]

======================================================================
ERROR: matplotlib.tests.test_backend_pgf.test_bbox_inches
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/matplotlib/matplotlib/venv/lib/python3.5/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/testing/decorators.py", line 422, in backend_switcher
    result = func(*args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/tests/test_backend_pgf.py", line 193, in test_bbox_inches
    tol=0)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/tests/test_backend_pgf.py", line 46, in compare_figure
    plt.savefig(actual, **savefig_kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/pyplot.py", line 686, in savefig
    res = fig.savefig(*args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/figure.py", line 1666, in savefig
    self.canvas.print_figure(*args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backend_bases.py", line 2232, in print_figure
    **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_pgf.py", line 894, in print_pdf
    self._print_pdf_to_fh(fh, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_pgf.py", line 848, in _print_pdf_to_fh
    self.print_pgf(fname_pgf, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_pgf.py", line 830, in print_pgf
    self._print_pgf_to_fh(fh, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_pgf.py", line 811, in _print_pgf_to_fh
    self.figure.draw(renderer)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/figure.py", line 1262, in draw
    renderer, self, dsu, self.suppressComposite)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/image.py", line 139, in _draw_list_compositing_images
    a.draw(renderer)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/axes/_base.py", line 2355, in draw
    mimage._draw_list_compositing_images(renderer, self, dsu)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/image.py", line 139, in _draw_list_compositing_images
    a.draw(renderer)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/axis.py", line 1133, in draw
    tick.draw(renderer)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/axis.py", line 268, in draw
    self.label1.draw(renderer)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/text.py", line 800, in draw
    ismath=ismath, mtext=mtext)
  File "/home/travis/build/matplotlib/matplotlib/lib/matplotlib/backends/backend_pgf.py", line 667, in draw_text
    text_args.append(valign[mtext.get_va()])
KeyError: 'center_baseline'

This looks like the render is breaking.

[mdboom]

Oh, and I should have read the error message first. It seems that PGF, unlike all other backends in the core, handles the text alignment itself -- or, more specifically, delgates it to the TeX engine. That seems like a corner case to me that most third-party backends won't face, but point taken that it could break them. However, we are bumping the major version number for the first time in years, if not now, when? :)

[tacaswell]

fair point.

[tacaswell]

I am 👍 on this, but given how many tests it touches someone else should agree as well.

[efiring]

In other words, ymin + height - baseline / 2. This is the same as 'top' minus baseline / 2 which makes sense, since baseline is the height starting from the baseline rather than the descender. Right?

[efiring]

In other words, it is identical to 'center'. Maybe it would be better to just make that explicit by using elif valign in ('center', 'center_baseline'). Would a short comment be enough to explain why this is?

[mdboom]

I'm trying to remember why this is -- going to run the tests again and see why...

[mdboom]

This was wrong, actually (and not addressed by existing tests, since it's a new vertical alignement type). Fixed now.

[efiring]

I think it is OK. The relevant part of the text code was already not so easy to understand, so I made a couple of suggestions for comments and simplification. I don't understand why the anchored rotation case is handled as it is.

[mdboom]

I've hopefully addressed @efiring's comments.

[tacaswell]

@mdboom Now you get to rebase this one 👿

[mdboom]

Rebased.

[mdboom]

I'll need to rerun tests and squash -- stay tuned...

[mdboom]

Passsing the tests! Let's merge this before I have to rebase and rebuild all the tests again :)

[mdboom]

I'm backporting this to 2.x now, but there's some conflicts, so it might take a while...

[mdboom]

Backported to 2.x as 5fb9d9e