matplotlib · jenshnielsen · Dec 30, 2014 · Nov 9, 2014 · Dec 30, 2014
diff --git a/lib/matplotlib/rcsetup.py b/lib/matplotlib/rcsetup.py
@@ -108,6 +108,16 @@ def validate_float(s):
         raise ValueError('Could not convert "%s" to float' % s)
 
 
+def validate_float_or_None(s):
+    """convert s to float or raise"""
+    if s is None:
+        return None
+    try:
+        return float(s)
+    except ValueError:
+        raise ValueError('Could not convert "%s" to float' % s)
+
+
 def validate_int(s):
     """convert s to int or raise"""
     try:
@@ -640,7 +650,7 @@ def __call__(self, s):
      # 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],
+    'legend.framealpha': [None, validate_float_or_None],
 
     ## the following dimensions are in fraction of the font size
     'legend.borderpad': [0.4, validate_float],  # units are fontsize

diff --git a/lib/matplotlib/tests/baseline_images/test_legend/rcparam_alpha.png b/lib/matplotlib/tests/baseline_images/test_legend/rcparam_alpha.png
diff --git a/lib/matplotlib/tests/baseline_images/test_legend/rgba_alpha.png b/lib/matplotlib/tests/baseline_images/test_legend/rgba_alpha.png
diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
@@ -64,6 +64,33 @@ def test_various_labels():
     ax.legend(numpoints=1, loc=0)
 
 
+@image_comparison(baseline_images=['rgba_alpha'],
+                  extensions=['png'], remove_text=True)
+def test_alpha_rgba():
+    import matplotlib.pyplot as plt
+
+    fig, ax = plt.subplots(1, 1)
+    ax.plot(range(10), lw=5)
+    leg = plt.legend(['Longlabel that will go away'], loc=10)
+    leg.legendPatch.set_facecolor([1, 0, 0, 0.5])
+
+
+@image_comparison(baseline_images=['rcparam_alpha'],
+                  extensions=['png'], remove_text=True)
+def test_alpha_rcparam():
+    import matplotlib.pyplot as plt
+
+    fig, ax = plt.subplots(1, 1)
+    ax.plot(range(10), lw=5)
+    with mpl.rc_context(rc={'legend.framealpha': .75}):
+        leg = plt.legend(['Longlabel that will go away'], loc=10)
+        # this alpha is going to be over-ridden by the rcparam whith
+        # sets the alpha of the patch to be non-None which causes the alpha
+        # value of the face color to be discarded.  This behavior may not be
+        # ideal, but it is what it is and we should keep track of it changing
+        leg.legendPatch.set_facecolor([1, 0, 0, 0.5])
+
+
 @image_comparison(baseline_images=['fancy'], remove_text=True)
 def test_fancy():
     # using subplot triggers some offsetbox functionality untested elsewhere

diff --git a/matplotlibrc.template b/matplotlibrc.template
@@ -255,10 +255,10 @@ backend      : %(backend)s
                                    # separator in the fr_FR locale.
 #axes.formatter.use_mathtext : False # When True, use mathtext for scientific
                                      # notation.
-#axes.formatter.useoffset      : True    # If True, the tick label formatter 
-                                         # will default to labeling ticks relative 
-                                         # to an offset when the data range is very 
-                                         # small compared to the minimum absolute 
+#axes.formatter.useoffset      : True    # If True, the tick label formatter
+                                         # will default to labeling ticks relative
+                                         # to an offset when the data range is very
+                                         # small compared to the minimum absolute
                                          # value of the data.
 
 #axes.unicode_minus  : True    # use unicode for the minus symbol
@@ -320,7 +320,7 @@ 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.framealpha    : None    # opacity of of legend frame
 #legend.scatterpoints : 3 # number of scatter points
 
 ### FIGURE
@@ -399,7 +399,7 @@ backend      : %(backend)s
 #savefig.jpeg_quality: 95       # when a jpeg is saved, the default quality parameter.
 #savefig.directory   : ~        # default directory in savefig dialog box,
                                 # leave empty to always use current working directory
-#savefig.transparent : False    # setting that controls whether figures are saved with a 
+#savefig.transparent : False    # setting that controls whether figures are saved with a
                                 # transparent background by default
 
 # tk backend params
@@ -489,5 +489,5 @@ backend      : %(backend)s
                                    # $PATH is searched
 #animation.mencoder_args: ''       # Additional arguments to pass to mencoder
 #animation.convert_path: 'convert' # Path to ImageMagick's convert binary.
-                                   # On Windows use the full path since convert 
+                                   # On Windows use the full path since convert
                                    # is also the name of a system tool.