Make _get_rgba_face actually always return a RGBA.

anntzer · anntzer · commit ee1334234213 · 2017-12-28T12:13:58.000-08:00
_get_rgba_face is an internal function that is only use to set the
graphicscontext's foreground color (in Line2D.draw); it is always
effectively called as `gc.set_foreground(line._get_rgba_face(...),
isRGBA=True)`.  So it makes sense to have it actually always return a
RGBA quadruplet, including when the color is "none" (in which case
`mcolors.to_rgba` returns (0, 0, 0, 0) regardless of alpha, which works
just fine).

This removes the need for third party graphicscontexts to handle
non-RGBA-quadruplets (specifically, None) even when set_foreground is
actually called with isRGBA=True.
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -495,13 +495,13 @@ def draw_path(self, gc, path, transform, rgbFace=None):
         """
         Draws a Path instance using the given affine transform.
         """
-        clip = (rgbFace is None and gc.get_hatch_path() is None)
+        clip = rgbFace is None and gc.get_hatch_path() is None
         simplify = path.should_simplify and clip
-        ps = self._convert_path(
-            path, transform, clip=clip, simplify=simplify)
+        ps = self._convert_path(path, transform, clip=clip, simplify=simplify)
         self._draw_ps(ps, gc, rgbFace)
 
-    def draw_markers(self, gc, marker_path, marker_trans, path, trans, rgbFace=None):
+    def draw_markers(
+            self, gc, marker_path, marker_trans, path, trans, rgbFace=None):
         """
         Draw the markers defined by path at each of the positions in x
         and y.  path coordinates are points, x and y coords will be
@@ -510,7 +510,9 @@ def draw_markers(self, gc, marker_path, marker_trans, path, trans, rgbFace=None)
         if debugPS: self._pswriter.write('% draw_markers \n')
 
         if rgbFace:
-            if rgbFace[0]==rgbFace[1] and rgbFace[0]==rgbFace[2]:
+            if len(rgbFace) == 4 and rgbFace[3] == 0:
+                return
+            if rgbFace[0] == rgbFace[1] == rgbFace[2]:
                 ps_color = '%1.3f setgray' % rgbFace[0]
             else:
                 ps_color = '%1.3f %1.3f %1.3f setrgbcolor' % rgbFace[:3]
diff --git a/lib/matplotlib/cbook/__init__.py b/lib/matplotlib/cbook/__init__.py
@@ -2766,3 +2766,23 @@ def _topmost_artist(
     in reverse order.
     """
     return _cached_max(reversed(artists))
+
+
+def _str_equal(obj, s):
+    """Return whether *obj* is a string equal to string *s*.
+
+    This helper solely exists to handle the case where *obj* is a numpy array,
+    because in such cases, a naive ``obj == s`` would yield an array, which
+    cannot be used in a boolean context.
+    """
+    return isinstance(obj, six.string_types) and obj == s
+
+
+def _str_lower_equal(obj, s):
+    """Return whether *obj* is a string equal, when lowercased, to string *s*.
+
+    This helper solely exists to handle the case where *obj* is a numpy array,
+    because in such cases, a naive ``obj == s`` would yield an array, which
+    cannot be used in a boolean context.
+    """
+    return isinstance(obj, six.string_types) and obj.lower() == s
diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -13,7 +13,7 @@
 
 import numpy as np
 
-from . import artist, colors as mcolors, docstring, rcParams
+from . import artist, cbook, colors as mcolors, docstring, rcParams
 from .artist import Artist, allow_rasterization
 from .cbook import (
     _to_unmasked_float_array, iterable, is_numlike, ls_mapper, ls_mapper_r,
@@ -793,16 +793,16 @@ def draw(self, renderer):
             rgbaFace = self._get_rgba_face()
             rgbaFaceAlt = self._get_rgba_face(alt=True)
             edgecolor = self.get_markeredgecolor()
-            if (isinstance(edgecolor, six.string_types)
-                    and edgecolor.lower() == 'none'):
+            if cbook._str_lower_equal(edgecolor, "none"):
                 gc.set_linewidth(0)
                 gc.set_foreground(rgbaFace, isRGBA=True)
             else:
                 gc.set_foreground(edgecolor)
                 gc.set_linewidth(self._markeredgewidth)
                 mec = self._markeredgecolor
-                if (isinstance(mec, six.string_types) and mec == 'auto' and
-                        rgbaFace is not None):
+                if (cbook._str_equal(mec, "auto")
+                        and not cbook._str_lower_equal(
+                            self.get_markerfacecolor(), "none")):
                     gc.set_alpha(rgbaFace[3])
                 else:
                     gc.set_alpha(self.get_alpha())
@@ -828,8 +828,7 @@ def draw(self, renderer):
                 marker_trans = marker.get_transform()
                 w = renderer.points_to_pixels(self._markersize)
 
-                if (isinstance(marker.get_marker(), six.string_types) and
-                        marker.get_marker() == ','):
+                if cbook._str_equal(marker.get_marker(), ","):
                     gc.set_linewidth(0)
                 else:
                     # Don't scale for pixels, and don't stroke them
@@ -843,8 +842,9 @@ def draw(self, renderer):
                 if alt_marker_path:
                     alt_marker_trans = marker.get_alt_transform()
                     alt_marker_trans = alt_marker_trans.scale(w)
-                    if (isinstance(mec, six.string_types) and mec == 'auto' and
-                            rgbaFaceAlt is not None):
+                    if (cbook._str_equal(mec, "auto")
+                            and not cbook._str_lower_equal(
+                                self.get_markerfacecoloralt(), "none")):
                         gc.set_alpha(rgbaFaceAlt[3])
                     else:
                         gc.set_alpha(self.get_alpha())
@@ -1257,13 +1257,7 @@ def update_from(self, other):
         self._drawstyle = other._drawstyle
 
     def _get_rgba_face(self, alt=False):
-        facecolor = self._get_markerfacecolor(alt=alt)
-        if (isinstance(facecolor, six.string_types)
-                and facecolor.lower() == 'none'):
-            rgbaFace = None
-        else:
-            rgbaFace = mcolors.to_rgba(facecolor, self._alpha)
-        return rgbaFace
+        return mcolors.to_rgba(self._get_markerfacecolor(alt=alt), self._alpha)
 
     def _get_rgba_ln_color(self, alt=False):
         return mcolors.to_rgba(self._color, self._alpha)
