Avoid redundant chr/ord calls in font tracking.

Almost every caller to `_font_supports_char` already has a code point,
and has to convert to a character, only for the former to convert it
back to a code point again.

Similarly, some callers to `CharacterTracker.track` only have a single
code point to add, so add some API to accept the glyph directly.

Author: QuLogic

lib/matplotlib/backends/_backend_pdf_ps.py

@@ -63,6 +63,10 @@ def track(self, font, s):
         """Record that string *s* is being typeset using font *font*."""
         self.used.setdefault(font.fname, set()).update(map(ord, s))
 
+    def track_glyph(self, font, glyph):
+        """Record that codepoint *glyph* is being typeset using font *font*."""
+        self.used.setdefault(font.fname, set()).add(glyph)
+
 
 class RendererPDFPSBase(RendererBase):
     # The following attributes must be defined by the subclasses:

lib/matplotlib/backends/backend_pdf.py

@@ -323,18 +323,18 @@ def pdfRepr(obj):
                         .format(type(obj)))
 
 
-def _font_supports_char(fonttype, char):
+def _font_supports_glyph(fonttype, glyph):
     """
-    Returns True if the font is able to provide *char* in a PDF.
+    Returns True if the font is able to provide codepoint *glyph* in a PDF.
 
     For a Type 3 font, this method returns True only for single-byte
-    chars.  For Type 42 fonts this method return True if the char is from
-    the Basic Multilingual Plane.
+    characters. For Type 42 fonts this method return True if the character is
+    from the Basic Multilingual Plane.
     """
     if fonttype == 3:
-        return ord(char) <= 255
+        return glyph <= 255
     if fonttype == 42:
-        return ord(char) <= 65535
+        return glyph <= 65535
     raise NotImplementedError()
 
 
@@ -1227,13 +1227,9 @@ def embedTTFType42(font, characters, descriptor):
             wObject = self.reserveObject('Type 0 widths')
             toUnicodeMapObject = self.reserveObject('ToUnicode map')
 
-            _log.debug(
-                "SUBSET %s characters: %s",
-                filename, "".join(chr(c) for c in characters)
-            )
-            fontdata = _backend_pdf_ps.get_glyphs_subset(
-                filename, "".join(chr(c) for c in characters)
-            )
+            subset_str = "".join(chr(c) for c in characters)
+            _log.debug("SUBSET %s characters: %s", filename, subset_str)
+            fontdata = _backend_pdf_ps.get_glyphs_subset(filename, subset_str)
             _log.debug(
                 "SUBSET %s %d -> %d", filename,
                 os.stat(filename).st_size, fontdata.getbuffer().nbytes
@@ -1327,7 +1323,7 @@ def embedTTFType42(font, characters, descriptor):
             # Add XObjects for unsupported chars
             glyph_ids = []
             for ccode in characters:
-                if not _font_supports_char(fonttype, chr(ccode)):
+                if not _font_supports_glyph(fonttype, ccode):
                     gind = full_font.get_char_index(ccode)
                     glyph_ids.append(gind)
 
@@ -2193,10 +2189,9 @@ def draw_mathtext(self, gc, x, y, s, prop, angle):
 
         self.file.output(Op.begin_text)
         for font, fontsize, num, ox, oy in glyphs:
-            char = chr(num)
-            self.file._character_tracker.track(font, char)
+            self.file._character_tracker.track_glyph(font, num)
             fontname = font.fname
-            if not _font_supports_char(fonttype, char):
+            if not _font_supports_glyph(fonttype, num):
                 # Unsupported chars (i.e. multibyte in Type 3 or beyond BMP in
                 # Type 42) must be emitted separately (below).
                 unsupported_chars.append((font, fontsize, ox, oy, num))
@@ -2383,7 +2378,7 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
             prev_was_multibyte = True
             for item in _text_helpers.layout(
                     s, font, kern_mode=KERNING_UNFITTED):
-                if _font_supports_char(fonttype, item.char):
+                if _font_supports_glyph(fonttype, ord(item.char)):
                     if prev_was_multibyte:
                         singlebyte_chunks.append((item.x, []))
                     if item.prev_kern:

lib/matplotlib/backends/backend_ps.py

@@ -670,7 +670,7 @@ def draw_mathtext(self, gc, x, y, s, prop, angle):
             f"{angle:f} rotate\n")
         lastfont = None
         for font, fontsize, num, ox, oy in glyphs:
-            self._character_tracker.track(font, chr(num))
+            self._character_tracker.track_glyph(font, num)
             if (font.postscript_name, fontsize) != lastfont:
                 lastfont = font.postscript_name, fontsize
                 self._pswriter.write(
@@ -955,13 +955,13 @@ def print_figure_impl(fh):
                         fh.write(_font_to_ps_type3(font_path, glyph_ids))
                     else:
                         try:
+                            subset_str = ''.join(chr(c) for c in chars)
                             _log.debug(
                                 "SUBSET %s characters: %s", font_path,
-                                ''.join(chr(c) for c in chars)
+                                subset_str
                             )
                             fontdata = _backend_pdf_ps.get_glyphs_subset(
-                                font_path, "".join(chr(c) for c in chars)
-                            )
+                                font_path, subset_str)
                             _log.debug(
                                 "SUBSET %s %d -> %d", font_path,
                                 os.stat(font_path).st_size,