Issue 1504: changed how draw handles alpha in markerfacecolor

CHANGELOG

@@ -21,6 +21,12 @@
            an active colorable artist, such as an image, and just sets
            up the colormap to use from that point forward. - PI
 
+2012-11-16 Added the funcction _get_rbga_face, which is identical to
+           _get_rbg_face except it return a (r,g,b,a) tuble, to line2D.
+           Modified Line2D.draw to use _get_rbga_face to get the markerface
+           color so that any alpha set by  markerfacecolor will respected.
+	   - Thomas Caswell
+
 2012-11-13 Add a symmetric log normalization class to colors.py.
            Also added some tests for the normalization class.
            Till Stensitzki

lib/matplotlib/lines.py

@@ -531,12 +531,12 @@ def draw(self, renderer):
         if self._marker:
             gc = renderer.new_gc()
             self._set_gc_clip(gc)
-            rgbFace = self._get_rgb_face()
-            rgbFaceAlt = self._get_rgb_face(alt=True)
+            rgbaFace = self._get_rgba_face()
+            rgbaFaceAlt = self._get_rgba_face(alt=True)
             edgecolor = self.get_markeredgecolor()
             if is_string_like(edgecolor) and edgecolor.lower() == 'none':
                 gc.set_linewidth(0)
-                gc.set_foreground(rgbFace)
+                gc.set_foreground(rgbaFace)
             else:
                 gc.set_foreground(edgecolor)
                 gc.set_linewidth(self._markeredgewidth)
@@ -574,16 +574,20 @@ def draw(self, renderer):
                     marker_trans = marker_trans.scale(w)
                 else:
                     gc.set_linewidth(0)
+                if rgbaFace is not None:
+                    gc.set_alpha(rgbaFace[3])
                 renderer.draw_markers(
                     gc, marker_path, marker_trans, subsampled, affine.frozen(),
-                    rgbFace)
+                    rgbaFace)
                 alt_marker_path = marker.get_alt_path()
                 if alt_marker_path:
+                    if rgbaFaceAlt is not None:
+                        gc.set_alpha(rgbaFaceAlt[3])
                     alt_marker_trans = marker.get_alt_transform()
                     alt_marker_trans = alt_marker_trans.scale(w)
                     renderer.draw_markers(
                         gc, alt_marker_path, alt_marker_trans, subsampled,
-                        affine.frozen(), rgbFaceAlt)
+                        affine.frozen(), rgbaFaceAlt)
 
             gc.restore()
 
@@ -961,6 +965,14 @@ def _get_rgb_face(self, alt=False):
             rgbFace = colorConverter.to_rgb(facecolor)
         return rgbFace
 
+    def _get_rgba_face(self, alt=False):
+        facecolor = self._get_markerfacecolor(alt=alt)
+        if is_string_like(facecolor) and facecolor.lower()=='none':
+            rgbaFace = None
+        else:
+            rgbaFace = colorConverter.to_rgba(facecolor)
+        return rgbaFace
+
     # some aliases....
     def set_aa(self, val):
         'alias for set_antialiased'

lib/matplotlib/tests/test_axes.py

@@ -962,6 +962,7 @@ def test_transparent_markers():
     ax = fig.add_subplot(111)
     ax.plot(data, 'D', mfc='none', markersize=100)
 
+
 @cleanup
 def test_mollweide_forward_inverse_closure():
     # test that the round-trip Mollweide forward->inverse transformation is an
@@ -1005,6 +1006,19 @@ def test_mollweide_inverse_forward_closure():
     # compare
     np.testing.assert_array_almost_equal(xy, xy2, 3)
 
+
+
+@image_comparison(baseline_images=['translucent_markers'], remove_text=True)
+def test_translucent_markers():
+    np.random.seed(0)
+    data = np.random.random(50)
+
+    fig = plt.figure()
+    ax = fig.add_subplot(111)
+    ax.plot(data, 'D', mfc=[1,0,0,.5], markersize=100)
+
+
+
 if __name__=='__main__':
     import nose
     nose.runmodule(argv=['-s','--with-doctest'], exit=False)