Move towards making texmanager stateless.

anntzer · anntzer · commit 0d4bc8e12522 · 2022-03-29T10:26:08.000+02:00
Previously, TexManager needed to call get_font_config at a specific
place in the middle of processing to update some internal attributes
before proceeding with TeX source generation.  Instead, move towards
making TexManager stateless (except for caching), i.e. the user facing
API should be thought of as a bunch of independently callable functions
`make_tex()`, `make_dvi()`, etc. (they will probably stay as methods on
a "empty" TexManager object for a long time for backcompat, in fact).
diff --git a/doc/api/next_api_changes/deprecations/22725-AL.rst b/doc/api/next_api_changes/deprecations/22725-AL.rst
@@ -0,0 +1,4 @@
+``TexManager.get_font_config``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+... is deprecated with no replacement.  (It previously returned an internal
+hashed key for used for caching purposes.)
diff --git a/lib/matplotlib/tests/test_texmanager.py b/lib/matplotlib/tests/test_texmanager.py
@@ -7,17 +7,14 @@
 
 
 def test_fontconfig_preamble():
-    """Test that the preamble is included in _fontconfig."""
+    """Test that the preamble is included in the source."""
     plt.rcParams['text.usetex'] = True
 
-    tm1 = TexManager()
-    font_config1 = tm1.get_font_config()
-
+    src1 = TexManager()._get_tex_source("", fontsize=12)
     plt.rcParams['text.latex.preamble'] = '\\usepackage{txfonts}'
-    tm2 = TexManager()
-    font_config2 = tm2.get_font_config()
+    src2 = TexManager()._get_tex_source("", fontsize=12)
 
-    assert font_config1 != font_config2
+    assert src1 != src2
 
 
 @pytest.mark.parametrize(
diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -61,37 +61,44 @@ class TexManager:
     """
 
     texcache = os.path.join(mpl.get_cachedir(), 'tex.cache')
-
     _grey_arrayd = {}
-    _font_family = 'serif'
+
     _font_families = ('serif', 'sans-serif', 'cursive', 'monospace')
-    _font_info = {
-        'new century schoolbook': ('pnc', r'\renewcommand{\rmdefault}{pnc}'),
-        'bookman': ('pbk', r'\renewcommand{\rmdefault}{pbk}'),
-        'times': ('ptm', r'\usepackage{mathptmx}'),
-        'palatino': ('ppl', r'\usepackage{mathpazo}'),
-        'zapf chancery': ('pzc', r'\usepackage{chancery}'),
-        'cursive': ('pzc', r'\usepackage{chancery}'),
-        'charter': ('pch', r'\usepackage{charter}'),
-        'serif': ('cmr', ''),
-        'sans-serif': ('cmss', ''),
-        'helvetica': ('phv', r'\usepackage{helvet}'),
-        'avant garde': ('pag', r'\usepackage{avant}'),
-        'courier': ('pcr', r'\usepackage{courier}'),
+    _font_preambles = {
+        'new century schoolbook': r'\renewcommand{\rmdefault}{pnc}',
+        'bookman': r'\renewcommand{\rmdefault}{pbk}',
+        'times': r'\usepackage{mathptmx}',
+        'palatino': r'\usepackage{mathpazo}',
+        'zapf chancery': r'\usepackage{chancery}',
+        'cursive': r'\usepackage{chancery}',
+        'charter': r'\usepackage{charter}',
+        'serif': '',
+        'sans-serif': '',
+        'helvetica': r'\usepackage{helvet}',
+        'avant garde': r'\usepackage{avant}',
+        'courier': r'\usepackage{courier}',
         # Loading the type1ec package ensures that cm-super is installed, which
         # is necessary for Unicode computer modern.  (It also allows the use of
         # computer modern at arbitrary sizes, but that's just a side effect.)
-        'monospace': ('cmtt', r'\usepackage{type1ec}'),
-        'computer modern roman': ('cmr', r'\usepackage{type1ec}'),
-        'computer modern sans serif': ('cmss', r'\usepackage{type1ec}'),
-        'computer modern typewriter': ('cmtt', r'\usepackage{type1ec}')}
+        'monospace': r'\usepackage{type1ec}',
+        'computer modern roman': r'\usepackage{type1ec}',
+        'computer modern sans serif': r'\usepackage{type1ec}',
+        'computer modern typewriter': r'\usepackage{type1ec}',
+    }
     _font_types = {
-        'new century schoolbook': 'serif', 'bookman': 'serif',
-        'times': 'serif', 'palatino': 'serif', 'charter': 'serif',
-        'computer modern roman': 'serif', 'zapf chancery': 'cursive',
-        'helvetica': 'sans-serif', 'avant garde': 'sans-serif',
+        'new century schoolbook': 'serif',
+        'bookman': 'serif',
+        'times': 'serif',
+        'palatino': 'serif',
+        'zapf chancery': 'cursive',
+        'charter': 'serif',
+        'helvetica': 'sans-serif',
+        'avant garde': 'sans-serif',
+        'courier': 'monospace',
+        'computer modern roman': 'serif',
         'computer modern sans serif': 'sans-serif',
-        'courier': 'monospace', 'computer modern typewriter': 'monospace'}
+        'computer modern typewriter': 'monospace',
+    }
 
     grey_arrayd = _api.deprecate_privatize_attribute("3.5")
     font_family = _api.deprecate_privatize_attribute("3.5")
@@ -103,33 +110,46 @@ def __new__(cls):
         Path(cls.texcache).mkdir(parents=True, exist_ok=True)
         return object.__new__(cls)
 
+    @_api.deprecated("3.6")
     def get_font_config(self):
+        preamble, font_cmd = self._get_font_preamble_and_command()
+        # Add a hash of the latex preamble to fontconfig so that the
+        # correct png is selected for strings rendered with same font and dpi
+        # even if the latex preamble changes within the session
+        preambles = preamble + font_cmd + self.get_custom_preamble()
+        return hashlib.md5(preambles.encode('utf-8')).hexdigest()
+
+    def _get_font_family_and_reduced(self):
         ff = rcParams['font.family']
         ff_val = ff[0].lower() if len(ff) == 1 else None
         reduced_notation = False
         if len(ff) == 1 and ff_val in self._font_families:
-            self._font_family = ff_val
-        elif len(ff) == 1 and ff_val in self._font_info:
-            reduced_notation = True
-            self._font_family = self._font_types[ff_val]
+            return ff_val, False
+        elif len(ff) == 1 and ff_val in self._font_preambles:
+            return self._font_types[ff_val], True
         else:
             _log.info('font.family must be one of (%s) when text.usetex is '
                       'True. serif will be used by default.',
                       ', '.join(self._font_families))
-            self._font_family = 'serif'
+            return 'serif', False
+
+    def _get_font_preamble_and_command(self):
+        requested_family, is_reduced_font = self._get_font_family_and_reduced()
 
-        fontconfig = [self._font_family]
-        fonts = {}
+        preambles = {}
         for font_family in self._font_families:
-            if reduced_notation and self._font_family == font_family:
-                fonts[font_family] = self._font_info[ff_val]
+            if is_reduced_font and font_family == requested_family:
+                preambles[font_family] = self._font_preambles[
+                    rcParams['font.family'][0].lower()]
             else:
                 for font in rcParams['font.' + font_family]:
-                    if font.lower() in self._font_info:
-                        fonts[font_family] = self._font_info[font.lower()]
+                    if font.lower() in self._font_preambles:
+                        preambles[font_family] = \
+                            self._font_preambles[font.lower()]
                         _log.debug(
                             'family: %s, font: %s, info: %s',
-                            font_family, font, self._font_info[font.lower()])
+                            font_family, font,
+                            self._font_preambles[font.lower()])
                         break
                     else:
                         _log.debug('%s font is not compatible with usetex.',
@@ -138,24 +158,20 @@ def get_font_config(self):
                     _log.info('No LaTeX-compatible font found for the %s font'
                               'family in rcParams. Using default.',
                               font_family)
-                    fonts[font_family] = self._font_info[font_family]
-            fontconfig.append(fonts[font_family][0])
-        # Add a hash of the latex preamble to fontconfig so that the
-        # correct png is selected for strings rendered with same font and dpi
-        # even if the latex preamble changes within the session
-        preamble_bytes = self.get_custom_preamble().encode('utf-8')
-        fontconfig.append(hashlib.md5(preamble_bytes).hexdigest())
+                    preambles[font_family] = self._font_preambles[font_family]
 
         # The following packages and commands need to be included in the latex
         # file's preamble:
-        cmd = {fonts[family][1]
+        cmd = {preambles[family]
                for family in ['serif', 'sans-serif', 'monospace']}
-        if self._font_family == 'cursive':
-            cmd.add(fonts['cursive'][1])
+        if requested_family == 'cursive':
+            cmd.add(preambles['cursive'])
         cmd.add(r'\usepackage{type1cm}')
-        self._font_preamble = '\n'.join(sorted(cmd))
-
-        return ''.join(fontconfig)
+        preamble = '\n'.join(sorted(cmd))
+        fontcmd = (r'\sffamily' if requested_family == 'sans-serif' else
+                   r'\ttfamily' if requested_family == 'monospace' else
+                   r'\rmfamily')
+        return preamble, fontcmd
 
     def get_basefile(self, tex, fontsize, dpi=None):
         """
@@ -169,26 +185,24 @@ def get_font_preamble(self):
         """
         Return a string containing font configuration for the tex preamble.
         """
-        return self._font_preamble
+        font_preamble, command = self._get_font_preamble_and_command()
+        return font_preamble
 
     def get_custom_preamble(self):
         """Return a string containing user additions to the tex preamble."""
         return rcParams['text.latex.preamble']
 
     def _get_tex_source(self, tex, fontsize):
         """Return the complete TeX source for processing a TeX string."""
-        self.get_font_config()  # Updates self._font_preamble.
+        font_preamble, fontcmd = self._get_font_preamble_and_command()
         baselineskip = 1.25 * fontsize
-        fontcmd = (r'\sffamily' if self._font_family == 'sans-serif' else
-                   r'\ttfamily' if self._font_family == 'monospace' else
-                   r'\rmfamily')
         return "\n".join([
             r"\documentclass{article}",
             r"% Pass-through \mathdefault, which is used in non-usetex mode",
             r"% to use the default text font but was historically suppressed",
             r"% in usetex mode.",
             r"\newcommand{\mathdefault}[1]{#1}",
-            self._font_preamble,
+            font_preamble,
             r"\usepackage[utf8]{inputenc}",
             r"\DeclareUnicodeCharacter{2212}{\ensuremath{-}}",
             r"% geometry is loaded before the custom preamble as ",
@@ -301,7 +315,7 @@ def get_grey(self, tex, fontsize=None, dpi=None):
             fontsize = rcParams['font.size']
         if not dpi:
             dpi = rcParams['savefig.dpi']
-        key = tex, self.get_font_config(), fontsize, dpi
+        key = self._get_tex_source(tex, fontsize), dpi
         alpha = self._grey_arrayd.get(key)
         if alpha is None:
             pngfile = self.make_png(tex, fontsize, dpi)
