Parse FontBBox in type1font.

anntzer · anntzer · commit c4e54cfc303c · 2025-05-20T11:59:41.000+02:00
... instead of having to go through ft2font in createType1Descriptor
just to extract the font bbox, ascender and descender.

FontBBox is gauranteed to exist in the type1 font definition by the
standard; its parsing as a size-4 array matches freetype's behavior (see
ps_parser_load_field); and using bbox entries as ascender and descender
also matches freetype's behavior (T1_Face_Init directly assigns
`root-&gt;ascender = (FT_Short)(root-&gt;bbox.yMax)` and likewise for the
descender; see also the docs for ascender and descender in FT_FaceRec).
diff --git a/doc/api/next_api_changes/deprecations/30088-AL.rst b/doc/api/next_api_changes/deprecations/30088-AL.rst
@@ -0,0 +1,4 @@
+*fontfile* parameter of ``PdfFile.createType1Descriptor``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+This parameter is deprecated; all relevant pieces of information are now
+directly extracted from the *t1font* argument.
diff --git a/lib/matplotlib/_type1font.py b/lib/matplotlib/_type1font.py
@@ -579,6 +579,16 @@ def _parse(self):
             extras = ('(?i)([ -](regular|plain|italic|oblique|(semi)?bold|'
                       '(ultra)?light|extra|condensed))+$')
             prop['FamilyName'] = re.sub(extras, '', prop['FullName'])
+
+        # Parse FontBBox
+        toks = [*_tokenize(prop['FontBBox'].encode('ascii'), True)]
+        if ([tok.kind for tok in toks]
+                != ['delimiter', 'number', 'number', 'number', 'number', 'delimiter']
+                or toks[-1].raw != toks[0].opposite()):
+            raise RuntimeError(
+                f"FontBBox should be a size-4 array, was {prop['FontBBox']}")
+        prop['FontBBox'] = [tok.value() for tok in toks[1:-1]]
+
         # Decrypt the encrypted parts
         ndiscard = prop.get('lenIV', 4)
         cs = prop['CharStrings']
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -1034,14 +1034,15 @@ def _embedTeXFont(self, fontinfo):
                    fontinfo.effects.get('extend', 1.0))
         fontdesc = self._type1Descriptors.get((fontinfo.fontfile, effects))
         if fontdesc is None:
-            fontdesc = self.createType1Descriptor(t1font, fontinfo.fontfile)
+            fontdesc = self.createType1Descriptor(t1font)
             self._type1Descriptors[(fontinfo.fontfile, effects)] = fontdesc
         fontdict['FontDescriptor'] = fontdesc
 
         self.writeObject(fontdictObject, fontdict)
         return fontdictObject
 
-    def createType1Descriptor(self, t1font, fontfile):
+    @_api.delete_parameter("3.11", "fontfile")
+    def createType1Descriptor(self, t1font, fontfile=None):
         # Create and write the font descriptor and the font file
         # of a Type-1 font
         fontdescObject = self.reserveObject('font descriptor')
@@ -1076,24 +1077,22 @@ def createType1Descriptor(self, t1font, fontfile):
         if 0:
             flags |= 1 << 18
 
-        ft2font = get_font(fontfile)
-
         descriptor = {
             'Type':        Name('FontDescriptor'),
             'FontName':    Name(t1font.prop['FontName']),
             'Flags':       flags,
-            'FontBBox':    ft2font.bbox,
+            'FontBBox':    t1font.prop['FontBBox'],
             'ItalicAngle': italic_angle,
-            'Ascent':      ft2font.ascender,
-            'Descent':     ft2font.descender,
+            'Ascent':      t1font.prop['FontBBox'][3],
+            'Descent':     t1font.prop['FontBBox'][1],
             'CapHeight':   1000,  # TODO: find this out
             'XHeight':     500,  # TODO: this one too
             'FontFile':    fontfileObject,
             'FontFamily':  t1font.prop['FamilyName'],
             'StemV':       50,  # TODO
             # (see also revision 3874; but not all TeX distros have AFM files!)
             # 'FontWeight': a number where 400 = Regular, 700 = Bold
-            }
+        }
 
         self.writeObject(fontdescObject, descriptor)
 
