Hide fully transparent text in PS output.

anntzer · anntzer · commit 3daceff12b51 · 2018-01-04T13:11:41.000-08:00
PS doesn't really support transparency (because the format itself
doesn't, unless using some nonstandard extensions), but has some special
casing for "fully transparent" (see e.g. "rgbFace is None" check in
_draw_ps).

Also implement the special-casing for text.
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -631,13 +631,16 @@ def draw_tex(self, gc, x, y, s, prop, angle, ismath='TeX!', mtext=None):
 
     def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
         """
-        draw a Text instance
+        Draw a Text instance.
         """
         # local to avoid repeated attribute lookups
         write = self._pswriter.write
         if debugPS:
             write("% text\n")
 
+        if gc.get_rgb() == (0, 0, 0, 0):
+            return  # Special handling for fully transparent.
+
         if ismath=='TeX':
             return self.draw_tex(gc, x, y, s, prop, angle)
 
