Add font feature API to FontProperties and Text #29695
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The What's New entry with libraqm will look something more like this (minus a bug with the kerning, hopefully): |
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A difficulty that I've not really handled with mplcairo but warrants at least discussion is what you want to do with subranges. Harfbuzz supports toggling a feature only for some of the characters (see https://harfbuzz.github.io/harfbuzz-hb-common.html#hb-feature-from-string, e.g. The two main alternatives I can think of are either to do nothing, like mplcairo (subranges are interpreted as "repeated over each line"), or to reparse ranges and reinterpret them as "indices over the full string" (after line splitting, matplotlib tweaks the actual ranges than get fed to harfbuzz when shaping each line). |
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Also, looking at this again, I wonder how well this will interact with font fallback: it seems not unreasonable that two entries in the font fallback list would want to use different font features (e.g., a latin script and a chinese script likely want very different font features). Perhaps the real question here is whether font fallback should really have been implemented by stashing (references to) multiple fonts in a single FontProperties (though I'm not sure I can immediately design something much better), but the PR here makes the question more salient, I'd say. |
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Since we have automatic wrapping ( For settings across font fallback, I guess that is possible to do, but it might require quite a bit of bookkeeping work. |
src/ft2font_wrapper.cpp
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| )"""; | ||
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| static void | ||
| PyFT2Font_set_features(PyFT2Font *self, py::object features_obj) |
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I think you can just take features_obj as a std::vector<std::string> unless you really want to restrict to taking tuples?
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The comments at #29794 (comment) also apply, but because this PR doesn't actually touch the rendering API, I guess it's fine. |
lib/matplotlib/font_manager.pyi
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| @@ -52,6 +52,7 @@ class FontProperties: | |||
| size: float | str | None = ..., | |||
| fname: str | os.PathLike | Path | None = ..., | |||
| math_fontfamily: str | None = ..., | |||
| features: list[str] | None = ..., | |||
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| features: list[str] | None = ..., | |
| features: tuple[str] | list[str] | None = ..., |
src/ft2font_wrapper.cpp
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| features.push_back(feature.cast<std::string>()); | ||
| } | ||
| } | ||
| self->x->set_features(std::move(features)); |
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Just to check my understanding, this is where we actually tell freetype to do anything ?
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Discussed on a developer call we decided to not implement the sub-range application yet. Promoting a tuple of strings to |
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Even if we don't explicitly support sub-ranges, we still need to decide what happens if someone writes e.g. |
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Since we moved the information from matplotlib/lib/matplotlib/text.py Line 805 in b4cb934 I tried a small change: diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
index 3b0de58814..b255a93c52 100644
--- a/lib/matplotlib/text.py
+++ b/lib/matplotlib/text.py
@@ -800,9 +800,7 @@ class Text(Artist):
angle = self.get_rotation()
for line, wh, x, y in info:
-
- mtext = self if len(info) == 1 else None
x = x + posx
y = y + posy
if renderer.flipy():
@@ -816,14 +814,19 @@ class Text(Artist):
else:
textrenderer = renderer
- if self.get_usetex():
- textrenderer.draw_tex(gc, x, y, clean_line,
- self._fontproperties, angle,
- mtext=mtext)
- else:
- textrenderer.draw_text(gc, x, y, clean_line,
- self._fontproperties, angle,
- ismath=ismath, mtext=mtext)
+ xt, yt = self.get_transform().inverted().transform((x, y))
+ with cbook._setattr_cm(self, _x=xt, _y=yt, _text=clean_line,
+ convert_xunits=lambda x: x,
+ convert_yunits=lambda y: y,
+ _horizontalalignment='left', _verticalalignment='bottom'):
+ if self.get_usetex():
+ textrenderer.draw_tex(gc, x, y, clean_line,
+ self._fontproperties, angle,
+ mtext=self)
+ else:
+ textrenderer.draw_text(gc, x, y, clean_line,
+ self._fontproperties, angle,
+ ismath=ismath, mtext=self)
gc.restore()
renderer.close_group('text')AFAICT, only the PGF backend uses matplotlib/lib/matplotlib/backends/backend_pgf.py Lines 697 to 700 in 6db18d5 |
Font features allow font designers to provide alternate glyphs or shaping within a single font. These features may be accessed via special tags corresponding to internal tables of glyphs. The mplcairo backend supports font features via an elaborate re-use of the font file path [1]. This commit adds the API to make this officially supported in the main user API. At this time, nothing in Matplotlib itself uses these settings, but they will have an effect with libraqm. [1] https://github.com/matplotlib/mplcairo/blob/v0.6.1/README.rst#font-formats-and-features
PR summary
Font features allow font designers to provide alternate glyphs or shaping within a single font. These features may be accessed via special tags corresponding to internal tables of glyphs.
The mplcairo backend supports font features via an elaborate re-use of the font file path. This commit adds the API to make this officially supported in the main user API.
At this time, nothing in Matplotlib itself uses these settings, but they will have an effect with libraqm. I am opening this PR early for review of the API while I work through some issues with the latter. Consequently, the What's New note will not show the effect of this API, and there are only smoke tests.
PR checklist