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GeezerVison is showing github.com — Add language parameter to Text objects by QuLogic · Pull Request #29794 · matplotlib/matplotlib

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@QuLogic

@QuLogic QuLogic commented Mar 22, 2025

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PR summary

Along with #29695, this language parameter is an additional setting that may affect text layout. As with the other PR, this is not complete, but rather something to get the API decided upon (and likely will be rebased on raqm PR after it's done.)

There are two parts to the API:

  1. the language parameter attached to Text, and any other API that wraps it (i.e., Axes.text or Axes.annotate)
  2. the language parameter in backend's Renderer.draw_text

At the moment, for both, I have set these to str | list[tuple[str, int, int]] where the latter denotes a list of (language, start, end)-tuples. However, this was before I found out about the font feature machinery, and it is possible that we may wish to use that syntax instead, at least for API part 1. For part 2, it's a little nicer to have the explicit types, just for passing to the FT2Font extension, but this may not be relevant to other implementations.

PR checklist

  • [n/a] "closes #0000" is in the body of the PR description to link the related issue
  • new and changed code is tested
  • Plotting related features are demonstrated in an example
  • New Features and API Changes are noted with a directive and release note
  • Documentation complies with general and docstring guidelines

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@QuLogic QuLogic added the topic: text label Mar 22, 2025
@QuLogic QuLogic added this to the v3.11.0 milestone Mar 22, 2025
@github-actions github-actions Bot added backend: pgf backend: agg backend: ps backend: pdf backend: svg backend: cairo topic: text/fonts topic: canvas and figure manager labels Mar 22, 2025
@QuLogic
QuLogic force-pushed the text-language branch from ffd43e9 to b3cfa4d Compare March 22, 2025 09:35
@anntzer

anntzer commented Mar 22, 2025 •
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re: adding language to draw_text: the general discussion about extensibility of renderer API applies, i.e.

  • if you're going to add language as a parameter to draw_text then it should be at least keyword-only.
  • it's likely that the more maintainable API would likely to just embed language as part of fontproperties (it's not really different from e.g. font features, I'd think) and tell the backend to read that info.
  • for draw_text we have actually more or less given up on having a "clean" renderer API because we pass the whole Text instance to draw_text (per Propagate mpl.text.Text instances to the backends and fix documentation #1081) anyways so perhaps backends that care could also just read that info off the Text instance. It feels a bit dirty, but heh... ("dirty" because we as well may just have a renderer API that's renderer.draw_text(textobj) to start with...)
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@anntzer anntzer mentioned this pull request Mar 22, 2025
Add font feature API to Text #29695
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@anntzer

anntzer commented Mar 28, 2025

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Side point regarding allowing list[tuple[str, int, int]] as language setting: this may be a problem if one uses somelanguage[idx:] to set the language from an index up to the end of the string (whose length could technically be modified later, even though it's not clear this necessarily makes much practical sense). Likely you need list[tuple[str, int, int | None]] (and then you may possibly support None (=0) for the start as well).
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@QuLogic QuLogic mentioned this pull request Apr 16, 2025
Fix signature of disabled draw methods #29923
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@QuLogic

QuLogic commented Apr 16, 2025

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In the call a couple weeks ago, we decided to drop the new language parameter to draw_text, because that already had a mtext parameter which contained the whole Text object. This would avoid any signature introspection.

However, one followup is that Renderer.get_text_width_height_descent would also depend on font features/language settings, and really should get these passed through somehow as well.
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@QuLogic
QuLogic force-pushed the text-language branch from b3cfa4d to 161e393 Compare April 17, 2025 08:40
@github-actions github-actions Bot removed backend: pgf backend: svg backend: cairo topic: canvas and figure manager labels Apr 17, 2025
@QuLogic
QuLogic force-pushed the text-language branch from 161e393 to f240057 Compare April 17, 2025 08:45
@QuLogic QuLogic mentioned this pull request May 2, 2025
Implement text shaping with libraqm #30000
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QuLogic
QuLogic commented May 7, 2025
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Comment thread lib/matplotlib/_text_helpers.py Resolved

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@QuLogic
QuLogic force-pushed the text-language branch from f240057 to 736bb64 Compare May 7, 2025 06:29
anntzer
anntzer reviewed May 10, 2025
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Comment thread lib/matplotlib/_text_helpers.py Outdated


def layout(string, font, *, kern_mode=Kerning.DEFAULT):
def layout(string, font, language, *, kern_mode=Kerning.DEFAULT):

@anntzer anntzer May 10, 2025

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These params should be kwonly? (throughout most of the PR, I think)

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anntzer
anntzer reviewed May 10, 2025
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Comment thread src/ft2font_wrapper.cpp Resolved

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@QuLogic
QuLogic force-pushed the text-language branch 2 times, most recently from 3c188df to 931423b Compare May 13, 2025 03:28
@QuLogic
QuLogic force-pushed the text-language branch from 931423b to 46c6239 Compare May 22, 2025 20:31
QuLogic
QuLogic commented Aug 27, 2025
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Comment thread src/ft2font.cpp Outdated

if (languages.has_value()) {
for (auto & [lang_str, start, end] : languages.value()) {
if (!raqm_set_language(rq, lang_str.c_str(), start, end)) {

@QuLogic QuLogic Aug 27, 2025 •
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This function actually takes a length, not an end location; I'm not sure which one we should accept (Harfbuzz feature tags use start/end, so maybe that?), but I'll have to update this to the correct naming (the test is setup to match what libraqm says, but the docs say the opposite.)

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@anntzer anntzer Aug 27, 2025

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start-stop looks normal as API to me?

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@QuLogic QuLogic Sep 3, 2025

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I agree and have made that change.

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@github-actions github-actions Bot added status: needs rebase and removed status: needs rebase labels Aug 27, 2025
@QuLogic
QuLogic force-pushed the text-language branch from 1858a56 to 6d35c9a Compare September 3, 2025 03:06
@github-actions github-actions Bot removed topic: mplot3d status: needs rebase labels Sep 3, 2025
@QuLogic QuLogic moved this from Waiting for other PR to Ready for Review in Font and text overhaul Sep 3, 2025
@QuLogic
QuLogic force-pushed the text-language branch 3 times, most recently from 6fc2dee to 6ef55ed Compare September 3, 2025 03:22
@QuLogic

QuLogic commented Sep 3, 2025 •
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Also extended the tests a bit to ensure that the results are as expected and fixed the fallback to the rcParam as well.

The test image is extracted to a separate commit as it should not be merged yet.
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@github-actions github-actions Bot added the status: needs rebase label Sep 16, 2025
@QuLogic
QuLogic force-pushed the text-language branch 2 times, most recently from d8051c2 to 886bf64 Compare September 19, 2025 05:55
@github-actions github-actions Bot removed the status: needs rebase label Sep 19, 2025
@QuLogic
QuLogic force-pushed the text-language branch 2 times, most recently from 0485aee to 3ffce36 Compare September 19, 2025 06:33
tacaswell
tacaswell reviewed Sep 19, 2025
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Comment thread doc/release/next_whats_new/text_language.rst Outdated
Comment on lines +35 to +36
fig.text(0, 0.1, f'English: {char}', fontsize=40, language='en')
fig.text(1, 0.1, f'Inari Sámi: {char}', fontsize=40, language='smn',

@tacaswell tacaswell Sep 19, 2025 •
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Super picky change to match the example ordering to the text ordering:

Suggested change
fig.text(0, 0.1, f'English: {char}', fontsize=40, language='en')
fig.text(1, 0.1, f'Inari Sámi: {char}', fontsize=40, language='smn',
fig.text(0, 0.1, f'Inari Sámi: {char}', fontsize=40, language='smn')
fig.text(1, 0.1, f'English: {char}', fontsize=40, language='en',

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tacaswell
tacaswell approved these changes Sep 19, 2025
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@tacaswell

tacaswell commented Sep 19, 2025

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It looks like the appveyor tests hung.
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@QuLogic
Add language parameter to Text objects
7ce8eae
@QuLogic
QuLogic force-pushed the text-language branch from 3ffce36 to 7ce8eae Compare September 20, 2025 03:05
@QuLogic

QuLogic commented Sep 20, 2025

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OK, I fixed the doc note, and moved the test image to the text-overhaul-figures branch in preparation for merging.
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@QuLogic
QuLogic merged commit 44c17bc into matplotlib:text-overhaul Sep 20, 2025
@QuLogic
QuLogic deleted the text-language branch September 20, 2025 04:13
@github-project-automation github-project-automation Bot moved this from Ready for Review to Done in Font and text overhaul Sep 20, 2025
@QuLogic QuLogic mentioned this pull request Sep 27, 2025
Prepare CharacterTracker for advanced font features #30608
Merged
1 task done
wavebyrd pushed a commit to wavebyrd/matplotlib that referenced this pull request Mar 13, 2026
@QuLogic
Merge pull request matplotlib#29794 from QuLogic/text-language
aab8a80 
Add language parameter to Text objects
QuLogic added a commit to QuLogic/matplotlib that referenced this pull request Apr 10, 2026
@QuLogic
Update test images for font/text overhaul
12d2a4d 
This includes images changes for the following pull requests / commits:

* [Fix center of rotation with
  rotation_mode='anchor'](matplotlib#29199)
  (c44db77)
* [Remove ttconv backwards-compatibility
  code](matplotlib#30145)
  (8caff88)
* [Remove kerning_factor from
  tests](matplotlib#29816)
  (7b4d725)
* [Set text hinting to
  defaults](matplotlib#29816)
  (8255ae2)
* [Update FreeType to
  2.13.3](matplotlib#29816)
  (89c054d)
* [Implement text shaping with
  libraqm](matplotlib#30000)
  (b0ded3a,
  9813523)
* [Add language parameter to Text
  objects](matplotlib#29794)
  (7ce8eae)
* [Fix auto-sized glyphs with BaKoMa
  fonts](matplotlib#29936)
  (3ba2c13)
* [pdf: Improve text with characters outside embedded font
  limits](matplotlib#30512)
  (b70fb88,
  6cedcf7)
* [Prepare `CharacterTracker` for advanced font
  features](matplotlib#30608)
  (8274e17,
  70dc388,
  df670cf,
  ed5e074)
* [Add font feature API to
  Text](matplotlib#29695)
  (972a688)
* [Fix spacing in r"$\max
  f$"](matplotlib#30715)
  (4a99a83)
* [Implement libraqm for vector
  outputs](matplotlib#30607)
  (bd17cd4)
* [Drop the FT2Font intermediate
  buffer](matplotlib#30059)
  (9d7d7b4)
* [Rasterize dvi files without
  dvipng](matplotlib#30039)
  (7627118)
* [Update bundled FreeType and HarfBuzz
  libraries](matplotlib#30938)
  (a161658,
  9619bcc)
* [Fix positioning of wide mathtext
  accents](matplotlib#31069)
  (c2fa7ba)
* [Refactor RendererAgg.draw_{mathtext,text,tex} to use same base
  algorithm](matplotlib#31085)
  (931bcf3)
* [Implement TeX's fraction and script
  alignment](matplotlib#31046)
  (94ff452,
  4bfa0f9,
  1cd8510)
* [Fix confusion between text height and ascent in metrics
  calculations](matplotlib#31107)
  (60f2310)
* [mathtext: Fetch quad width & axis height from font
  metrics](matplotlib#31110)
  (692df3f,
  383028b)
* [mathtext: add mathnormal and distinguish between normal and italic
  family](matplotlib#31121)
  (a6913f3)
* [ENH: Ignore empty text for
  tightbbox](matplotlib#31285)
  (d772043)
* [Drop axis_artist tickdir image compat, due to text-overhaul
  merge](matplotlib#31281)
  (2057583)
* [text: Use font metrics to determine line
  heights](matplotlib#31291)
  (3ab6a27,
  d961462,
  97f4943)
* [ps/pdf: Override font height metrics to support AFM
  files](matplotlib#31371)
  (e0913d4)
* [TST: Cleanup back-compat code in tests touched by text
  overhaul](matplotlib#31295)
  (7c33379)
* [TST: Set tests touched by text overhaul to mpl20
  style](matplotlib#31300)
  (41c4d8d)
@QuLogic QuLogic mentioned this pull request Apr 10, 2026
Font and text overhaul #30161
Merged
4 tasks done
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@anntzer anntzer anntzer left review comments
@tacaswell tacaswell tacaswell approved these changes
@story645 story645 story645 approved these changes

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backend: agg backend: pdf backend: ps topic: rcparams topic: text/fonts topic: text

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Font and text overhaul
Status: Done

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v3.11.0

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@QuLogic @anntzer @tacaswell @story645
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