Merge pull request matplotlib#3369 from e-q/legendFrameAlpha

BUG : Added legend.framealpha to rcParams, as mentioned in axes.legend docstring

Author: tacaswell

lib/matplotlib/legend.py

@@ -367,7 +367,9 @@ def __init__(self, parent, handles, labels,
         # init with null renderer
         self._init_legend_box(handles, labels)
 
-        if framealpha is not None:
+        if framealpha is None:
+            self.get_frame().set_alpha(rcParams["legend.framealpha"])
+        else:
             self.get_frame().set_alpha(framealpha)
 
         self._loc = loc

lib/matplotlib/rcsetup.py

@@ -632,7 +632,8 @@ def __call__(self, s):
     'legend.shadow': [False, validate_bool],
      # whether or not to draw a frame around legend
     'legend.frameon': [True, validate_bool],
-
+     # alpha value of the legend frame
+    'legend.framealpha': [1.0, validate_float],
 
     ## the following dimensions are in fraction of the font size
     'legend.borderpad': [0.4, validate_float],  # units are fontsize

matplotlibrc.template

@@ -316,6 +316,7 @@ backend      : %(backend)s
 #legend.columnspacing : 2.    # the border between the axes and legend edge in fraction of fontsize
 #legend.shadow        : False
 #legend.frameon       : True   # whether or not to draw a frame around legend
+#legend.framealpha    : 1.0    # opacity of of legend frame
 #legend.scatterpoints : 3 # number of scatter points
 
 ### FIGURE