Merge pull request matplotlib#18397 from casperdcl/patch-1

FIX: cmr10 negative sign in cmsy10 (RuntimeWarning: Glyph 8722 missing)

Author: tacaswell

lib/matplotlib/_mathtext.py

@@ -519,6 +519,11 @@ def _get_glyph(self, fontname, font_class, sym, fontsize, math=True):
             found_symbol = False
             font = self._get_font(new_fontname)
             if font is not None:
+                if font.family_name == "cmr10" and uniindex == 0x2212:
+                    # minus sign exists in cmsy10 (not cmr10)
+                    font = get_font(
+                        cbook._get_data_path("fonts/ttf/cmsy10.ttf"))
+                    uniindex = 0xa1
                 glyphindex = font.get_char_index(uniindex)
                 if glyphindex != 0:
                     found_symbol = True

lib/matplotlib/tests/test_mathtext.py

@@ -385,3 +385,15 @@ def test_math_fontfamily():
              size=24, math_fontfamily='dejavusans')
     fig.text(0.2, 0.3, r"$This\ text\ should\ have\ another$",
              size=24, math_fontfamily='stix')
+
+
+def test_mathtext_cmr10_minus_sign():
+    # cmr10 does not contain a minus sign and used to issue a warning
+    # RuntimeWarning: Glyph 8722 missing from current font.
+    mpl.rcParams['font.family'] = 'cmr10'
+    mpl.rcParams['axes.formatter.use_mathtext'] = True
+    fig, ax = plt.subplots()
+    ax.plot(range(-1, 1), range(-1, 1))
+    with pytest.warns(None) as record:
+        fig.canvas.draw()
+    assert len(record) == 0, "\n".join(str(e.message) for e in record)