API: add lines.scale_dashes rcParam

This is something that we probably want to expose as a knob without
forcing full classic mode.

Closes matplotlib#6998

Author: tacaswell

doc/users/whats_new.rst

@@ -87,6 +87,9 @@ New rcparams added
 |                                 | `int`, a list of floats, or ``'auto'`` if numpy  |
 |                                 | >= 1.11 is installed.                            |
 +---------------------------------+--------------------------------------------------+
+|`lines.scale_dashes`             | If the line dash patterns should scale with      |
+|                                 | linewidth                                        |
++---------------------------------+--------------------------------------------------+
 
 
 

lib/matplotlib/lines.py

@@ -66,7 +66,7 @@ def _get_dash_pattern(style):
 
 
 def _scale_dashes(offset, dashes, lw):
-    if rcParams['_internal.classic_mode']:
+    if not rcParams['lines.scale_dashes']:
         return offset, dashes
     scale = max(2.0, lw)
     scaled_offset = scaled_dashes = None

lib/matplotlib/mpl-data/stylelib/classic.mplstyle

@@ -18,6 +18,7 @@ lines.antialiased : True         # render lines in antialiased (no jaggies)
 lines.dashed_pattern : 6, 6
 lines.dashdot_pattern : 3, 5, 1, 5
 lines.dotted_pattern : 1, 3
+lines.scale_dashes: False
 
 ### Marker props
 markers.fillstyle: full

lib/matplotlib/rcsetup.py

@@ -902,6 +902,7 @@ def validate_hist_bins(s):
     'lines.dashed_pattern':  [[2.8, 1.2], validate_nseq_float()],
     'lines.dashdot_pattern': [[4.8, 1.2, 0.8, 1.2], validate_nseq_float()],
     'lines.dotted_pattern':  [[1.1, 1.1], validate_nseq_float()],
+    'lines.scale_dashes':  [True, validate_bool],
 
     # marker props
     'markers.fillstyle': ['full', validate_fillstyle],

matplotlibrc.template

@@ -94,6 +94,7 @@ backend      : $TEMPLATE_BACKEND
 #lines.dashed_pattern : 2.8, 1.2
 #lines.dashdot_pattern : 4.8, 1.2, 0.8, 1.2
 #lines.dotted_pattern : 1.2, 0.6
+#lines.scale_dashes : True
 
 #markers.fillstyle: full # full|left|right|bottom|top|none