Disable use of FreeType in dvipng for test reproducibility.

anntzer · anntzer · commit 0cdd0e8e35d4 · 2020-04-06T11:18:57.000+02:00
Unfortunately at least some dvipngs appear to be statically linked to
FreeType so we can't play tricks with LD_PRELOAD/LD_LIBRARY_PATH.
diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -350,9 +350,16 @@ def make_png(self, tex, fontsize, dpi):
         # see get_rgba for a discussion of the background
         if not os.path.exists(pngfile):
             dvifile = self.make_dvi(tex, fontsize)
-            self._run_checked_subprocess(
-                ["dvipng", "-bg", "Transparent", "-D", str(dpi),
-                 "-T", "tight", "-o", pngfile, dvifile], tex)
+            cmd = ["dvipng", "-bg", "Transparent", "-D", str(dpi),
+                   "-T", "tight", "-o", pngfile, dvifile]
+            # When testing, disable FreeType rendering for reproducibility; but
+            # dvipng 1.16 has a bug (fixed in f3ff241) that breaks --freetype0
+            # mode, so for it we keep FreeType enabled; the image will be
+            # slightly off.
+            if (getattr(mpl, "_called_from_pytest", False)
+                    and mpl._get_executable_info("dvipng").version != "1.16"):
+                cmd.insert(1, "--freetype0")
+            self._run_checked_subprocess(cmd, tex)
         return pngfile
 
     def get_grey(self, tex, fontsize=None, dpi=None):
