Clarify error with usetex when cm-super is not installed.

anntzer · anntzer · commit 20e705ba17e5 · 2019-05-07T14:24:20.000+02:00
This PR makes the error when cm-super is not installed (and
rcParams["text.latex.unicode"] = True, which is now the default) be
```
! LaTeX Error: File `type1ec.sty' not found.

Type X to quit or &lt;RETURN&gt; to proceed,
or enter new name. (Default extension: sty)

Enter file name:
! Emergency stop.
&lt;read *&gt;

l.5 \usepackage
               {type1ec}^^M
No pages of output.
```
(or, if using miktex, miktex will prompt for installing cm-super).
diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -86,10 +86,13 @@ class TexManager(object):
         'helvetica': ('phv', r'\usepackage{helvet}'),
         'avant garde': ('pag', r'\usepackage{avant}'),
         'courier': ('pcr', r'\usepackage{courier}'),
-        'monospace': ('cmtt', ''),
-        'computer modern roman': ('cmr', ''),
-        'computer modern sans serif': ('cmss', ''),
-        'computer modern typewriter': ('cmtt', '')}
+        # 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}')}
 
     _rc_cache = None
     _rc_cache_keys = (
