Merge pull request #18798 from jkseppan/deprecate-afm-mathtext

timhoffm · web-flow · commit 2e75ed0f1c66 · 2020-10-23T14:19:15.000+02:00
Deprecate ps.useafm for mathtext
diff --git a/doc/api/next_api_changes/deprecations/18798-JKS.rst b/doc/api/next_api_changes/deprecations/18798-JKS.rst
@@ -0,0 +1,8 @@
+``ps.useafm`` deprecated for mathtext
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Outputting mathtext using only standard PostScript fonts has likely
+been broken for a while (issue `#18722
+<https://github.com/matplotlib/matplotlib/issues/18722>`_). In
+Matplotlib 3.5, the setting ``ps.useafm`` will have no effect on
+mathtext.
diff --git a/lib/matplotlib/mathtext.py b/lib/matplotlib/mathtext.py
@@ -433,6 +433,19 @@ def parse(self, s, dpi=72, prop=None, *, _force_standard_ps_fonts=False):
         The results are cached, so multiple calls to `parse`
         with the same expression should be fast.
         """
+        if _force_standard_ps_fonts:
+            cbook.warn_deprecated(
+                "3.4",
+                removal="3.5",
+                message=(
+                    "Mathtext using only standard PostScript fonts has "
+                    "been likely to produce wrong output for a while, "
+                    "has been deprecated in %(since)s and will be removed "
+                    "in %(removal)s, after which ps.useafm will have no "
+                    "effect on mathtext."
+                )
+            )
+
         # lru_cache can't decorate parse() directly because the ps.useafm and
         # mathtext.fontset rcParams also affect the parse (e.g. by affecting
         # the glyph metrics).
diff --git a/lib/matplotlib/tests/test_backend_ps.py b/lib/matplotlib/tests/test_backend_ps.py
@@ -9,6 +9,7 @@
 import matplotlib.pyplot as plt
 from matplotlib import cbook, patheffects
 from matplotlib.testing.decorators import image_comparison
+from matplotlib.cbook import MatplotlibDeprecationWarning
 
 
 needs_ghostscript = pytest.mark.skipif(
@@ -59,6 +60,8 @@ def test_savefig_to_stringio(format, use_log, rcParams, orientation):
             allowable_exceptions.append(mpl.ExecutableNotFoundError)
         if rcParams.get("text.usetex"):
             allowable_exceptions.append(RuntimeError)
+        if rcParams.get("ps.useafm"):
+            allowable_exceptions.append(MatplotlibDeprecationWarning)
         try:
             fig.savefig(s_buf, format=format, orientation=orientation)
             fig.savefig(b_buf, format=format, orientation=orientation)
