Hide fully transparent latex text in PS output.

This problem was fixed before for non-latex text. However, when using
latex to render transparent text, it would still show up in PS output.

Author: yschroeder

lib/matplotlib/backends/backend_ps.py

@@ -593,6 +593,9 @@ def draw_path_collection(self, gc, master_transform, paths, all_transforms,
     @_log_if_debug_on
     def draw_tex(self, gc, x, y, s, prop, angle, *, mtext=None):
         # docstring inherited
+        if self._is_transparent(gc.get_rgb()):
+            return  # Special handling for fully transparent.
+
         if not hasattr(self, "psfrag"):
             self._logwarn_once(
                 "The PS backend determines usetex status solely based on "

lib/matplotlib/tests/test_backend_ps.py

@@ -118,6 +118,16 @@ def test_transparency():
     ax.text(.5, .5, "foo", color="r", alpha=0)
 
 
+@needs_usetex
+@image_comparison(["empty.eps"])
+def test_transparency_tex():
+    mpl.rcParams['text.usetex'] = True
+    fig, ax = plt.subplots()
+    ax.set_axis_off()
+    ax.plot([0, 1], color="r", alpha=0)
+    ax.text(.5, .5, "foo", color="r", alpha=0)
+
+
 def test_bbox():
     fig, ax = plt.subplots()
     with io.BytesIO() as buf: