added 'savefig.transparent' rcParams

Closes issue matplotlib#2388

Author: tacaswell

doc/api/api_changes.rst

@@ -59,6 +59,9 @@ original location:
   thus `colorbar.ColorbarBase.outline` is now a
   `matplotlib.patches.Polygon` object.
 
+* The rcParams `savefig.transparent` has been added to control
+  default transparency when saving figures.
+
 .. _changes_in_1_3:
 
 

lib/matplotlib/figure.py

@@ -1414,7 +1414,7 @@ def savefig(self, *args, **kwargs):
 
         kwargs.setdefault('dpi', rcParams['savefig.dpi'])
         frameon = kwargs.pop('frameon', rcParams['savefig.frameon'])
-        transparent = kwargs.pop('transparent', False)
+        transparent = kwargs.pop('transparent', rcParams['savefig.transparent'])
 
         if transparent:
             kwargs.setdefault('facecolor', 'none')

lib/matplotlib/rcsetup.py

@@ -714,6 +714,7 @@ def __call__(self, s):
     'savefig.pad_inches': [0.1, validate_float],
     # default directory in savefig dialog box
     'savefig.directory': ['~', six.text_type],
+    'savefig.transparent': [False, validate_bool],
 
     # Maintain shell focus for TkAgg
     'tk.window_focus':  [False, validate_bool],

matplotlibrc.template

@@ -377,6 +377,7 @@ 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    # should transparency be enabled by default
 
 # tk backend params
 #tk.window_focus   : False    # Maintain shell focus for TkAgg