Backport PR matplotlib#26529: Fix MathText antialiasing

lib/matplotlib/_mathtext.py

@@ -106,7 +106,7 @@ def to_vector(self):
               for x1, y1, x2, y2 in self.rects]
         return VectorParse(w, h + d, d, gs, rs)
 
-    def to_raster(self, antialiased=None):
+    def to_raster(self, *, antialiased):
         # Metrics y's and mathtext y's are oriented in opposite directions,
         # hence the switch between ymin and ymax.
         xmin = min([*[ox + info.metrics.xmin for ox, oy, info in self.glyphs],
@@ -128,7 +128,6 @@ def to_raster(self, antialiased=None):
         # old approach and keeps baseline images backcompat.
         shifted = ship(self.box, (-xmin, -ymin))
 
-        antialiased = mpl.rcParams['text.antialiased']
         for ox, oy, info in shifted.glyphs:
             info.font.draw_glyph_to_bitmap(
                 image, ox, oy - info.metrics.iceberg, info.glyph,

lib/matplotlib/mathtext.py

@@ -75,8 +75,7 @@ def parse(self, s, dpi=72, prop=None, *, antialiased=None):
         # is mutable; key the cache using an internal copy (see
         # text._get_text_metrics_with_cache for a similar case).
         prop = prop.copy() if prop is not None else None
-        if antialiased is None:
-            antialiased = mpl.rcParams['text.antialiased']
+        antialiased = mpl._val_or_rc(antialiased, 'text.antialiased')
         return self._parse_cached(s, dpi, prop, antialiased)
 
     @functools.lru_cache(50)

lib/matplotlib/tests/test_text.py

@@ -186,19 +186,23 @@ def draw_box(ax, tt):
     ax.text(1.2, 0.1, 'Bot align, rot20', color='C2')
 
 
-@image_comparison(['antialiased.png'])
+@image_comparison(['antialiased.png'], style='mpl20')
 def test_antialiasing():
-    mpl.rcParams['text.antialiased'] = True
+    mpl.rcParams['text.antialiased'] = False  # Passed arguments should override.
 
     fig = plt.figure(figsize=(5.25, 0.75))
-    fig.text(0.5, 0.75, "antialiased", horizontalalignment='center',
-             verticalalignment='center')
-    fig.text(0.5, 0.25, r"$\sqrt{x}$", horizontalalignment='center',
-             verticalalignment='center')
-    # NOTE: We don't need to restore the rcParams here, because the
-    # test cleanup will do it for us.  In fact, if we do it here, it
-    # will turn antialiasing back off before the images are actually
-    # rendered.
+    fig.text(0.3, 0.75, "antialiased", horizontalalignment='center',
+             verticalalignment='center', antialiased=True)
+    fig.text(0.3, 0.25, r"$\sqrt{x}$", horizontalalignment='center',
+             verticalalignment='center', antialiased=True)
+
+    mpl.rcParams['text.antialiased'] = True  # Passed arguments should override.
+    fig.text(0.7, 0.75, "not antialiased", horizontalalignment='center',
+             verticalalignment='center', antialiased=False)
+    fig.text(0.7, 0.25, r"$\sqrt{x}$", horizontalalignment='center',
+             verticalalignment='center', antialiased=False)
+
+    mpl.rcParams['text.antialiased'] = False  # Should not affect existing text.
 
 
 def test_afm_kerning():
@@ -914,29 +918,18 @@ def test_annotate_offset_fontsize():
     assert str(points_coords) == str(fontsize_coords)
 
 
-def test_set_antialiased():
+def test_get_set_antialiased():
     txt = Text(.5, .5, "foo\nbar")
     assert txt._antialiased == mpl.rcParams['text.antialiased']
+    assert txt.get_antialiased() == mpl.rcParams['text.antialiased']
 
     txt.set_antialiased(True)
     assert txt._antialiased is True
+    assert txt.get_antialiased() == txt._antialiased
 
     txt.set_antialiased(False)
     assert txt._antialiased is False
-
-
-def test_get_antialiased():
-
-    txt2 = Text(.5, .5, "foo\nbar", antialiased=True)
-    assert txt2._antialiased is True
-    assert txt2.get_antialiased() == txt2._antialiased
-
-    txt3 = Text(.5, .5, "foo\nbar", antialiased=False)
-    assert txt3._antialiased is False
-    assert txt3.get_antialiased() == txt3._antialiased
-
-    txt4 = Text(.5, .5, "foo\nbar")
-    assert txt4.get_antialiased() == mpl.rcParams['text.antialiased']
+    assert txt.get_antialiased() == txt._antialiased
 
 
 def test_annotation_antialiased():
@@ -957,39 +950,6 @@ def test_annotation_antialiased():
     assert annot4._antialiased == mpl.rcParams['text.antialiased']
 
 
-@check_figures_equal()
-def test_text_antialiased_off_default_vs_manual(fig_test, fig_ref):
-    fig_test.text(0.5, 0.5, '6 inches x 2 inches',
-                             antialiased=False)
-
-    mpl.rcParams['text.antialiased'] = False
-    fig_ref.text(0.5, 0.5, '6 inches x 2 inches')
-
-
-@check_figures_equal()
-def test_text_antialiased_on_default_vs_manual(fig_test, fig_ref):
-    fig_test.text(0.5, 0.5, '6 inches x 2 inches', antialiased=True)
-
-    mpl.rcParams['text.antialiased'] = True
-    fig_ref.text(0.5, 0.5, '6 inches x 2 inches')
-
-
-@check_figures_equal()
-def test_text_math_antialiased_on_default_vs_manual(fig_test, fig_ref):
-    fig_test.text(0.5, 0.5, r"OutsideMath $I\'m \sqrt{2}$", antialiased=True)
-
-    mpl.rcParams['text.antialiased'] = True
-    fig_ref.text(0.5, 0.5, r"OutsideMath $I\'m \sqrt{2}$")
-
-
-@check_figures_equal()
-def test_text_math_antialiased_off_default_vs_manual(fig_test, fig_ref):
-    fig_test.text(0.5, 0.5, r"OutsideMath $I\'m \sqrt{2}$", antialiased=False)
-
-    mpl.rcParams['text.antialiased'] = False
-    fig_ref.text(0.5, 0.5, r"OutsideMath $I\'m \sqrt{2}$")
-
-
 @check_figures_equal(extensions=["png"])
 def test_annotate_and_offsetfrom_copy_input(fig_test, fig_ref):
     # Both approaches place the text (10, 0) pixels away from the center of the line.