FIX: also include fonts from generic family in fallback

tacaswell · tacaswell · commit eab91a402fa4 · 2022-08-31T20:31:35.000-04:00
If we pass the generic family to `_findfont_cached` it will still only return 1
font.  This is a problem if we need a glyph which is not in the first font in
the generic font list that is actually installed on the system.

This is not the most elegant code, but it works.
diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -1402,27 +1402,48 @@ def _find_fonts_by_props(self, prop, fontext='ttf', directory=None,
 
         fpaths = []
         for family in prop.get_family():
-            cprop = prop.copy()
-            cprop.set_family(family)  # set current prop's family
+            if family in font_family_aliases:
+                # deal with the sans/san-serif/sans serif issue
+                generic_family = {
+                    'sans': 'sans-serif',
+                    'sans serif': 'sans-serif'
+                }.get(family, family)
+
+                for fam in filter(
+                        lambda _: _ not in font_family_aliases,
+                        mpl.rcParams[f'font.{generic_family}']
+                ):
+                    cprop = prop.copy()
+                    cprop.set_family(fam)
+                    try:
+                        # for each of the fonts in the fallback chain look it up
+                        fpaths.append(
+                            self.findfont(
+                                cprop, fontext, directory,
+                                fallback_to_default=False,  # don't fallback to default
+                                rebuild_if_missing=rebuild_if_missing,
+                            )
+                        )
+
+                    except ValueError:
+                        # but do not worry if one is missing
+                        ...
+            else:
+                cprop = prop.copy()
+                cprop.set_family(family)  # set current prop's family
 
-            try:
-                fpaths.append(
-                    self.findfont(
-                        cprop, fontext, directory,
-                        fallback_to_default=False,  # don't fallback to default
-                        rebuild_if_missing=rebuild_if_missing,
-                    )
-                )
-            except ValueError:
-                if family in font_family_aliases:
-                    _log.warning(
-                        "findfont: Generic family %r not found because "
-                        "none of the following families were found: %s",
-                        family, ", ".join(self._expand_aliases(family))
+                try:
+                    fpaths.append(
+                        self.findfont(
+                            cprop, fontext, directory,
+                            fallback_to_default=False,  # don't fallback to default
+                            rebuild_if_missing=rebuild_if_missing,
+                        )
                     )
-                else:
+                except ValueError:
                     _log.warning("findfont: Font family %r not found.", family)
 
+
         # only add default family if no other font was found and
         # fallback_to_default is enabled
         if not fpaths:
