Make hatch linewidth an rcParam

doc/users/whats_new/style_changes.rst

@@ -35,6 +35,18 @@ Plots
   the rcParam ``lines.markersize`` so it is consistent with ``plot(X,
   Y, 'o')``.  The old value was 20, and the new value is 36 (6^2).
 
+Hatching
+````````
+
+- The width of the lines in a hatch pattern is now configurable by the
+  rcParam `hatch.linewidth`, with a default of 1 point.  The old
+  behavior was different depending on backend:
+
+    - PDF: 0.1 pt
+    - SVG: 1.0 pt
+    - PS:  1 px
+    - Agg: 1 px
+
 Plot layout
 ```````````
 

lib/matplotlib/backend_bases.py

@@ -792,6 +792,7 @@ def __init__(self):
         self._linewidth = 1
         self._rgb = (0.0, 0.0, 0.0, 1.0)
         self._hatch = None
+        self._hatch_linewidth = rcParams['hatch.linewidth']
         self._url = None
         self._gid = None
         self._snap = None
@@ -1111,6 +1112,12 @@ def get_hatch_path(self, density=6.0):
             return None
         return Path.hatch(self._hatch, density)
 
+    def get_hatch_linewidth(self):
+        """
+        Gets the linewidth to use for hatching.
+        """
+        return self._hatch_linewidth
+
     def get_sketch_params(self):
         """
         Returns the sketch parameters for the artist.

lib/matplotlib/backends/backend_pdf.py

@@ -1182,7 +1182,7 @@ def writeHatches(self):
                             0, 0, sidelen, sidelen, Op.rectangle,
                             Op.fill)
 
-            self.output(0.1, Op.setlinewidth)
+            self.output(rcParams['hatch.linewidth'], Op.setlinewidth)
 
             # TODO: We could make this dpi-dependent, but that would be
             # an API change

lib/matplotlib/backends/backend_ps.py

@@ -303,6 +303,7 @@ def create_hatch(self, hatch):
         if hatch in self._hatches:
             return self._hatches[hatch]
         name = 'H%d' % len(self._hatches)
+        linewidth = rcParams['hatch.linewidth']
         self._pswriter.write("""\
   << /PatternType 1
      /PaintType 2
@@ -313,7 +314,7 @@ def create_hatch(self, hatch):
 
      /PaintProc {
         pop
-        0 setlinewidth
+        %(linewidth)f setlinewidth
 """ % locals())
         self._pswriter.write(
             self._convert_path(Path.hatch(hatch), Affine2D().scale(72.0),

lib/matplotlib/backends/backend_svg.py

@@ -393,7 +393,7 @@ def _write_hatches(self):
                 style=generate_css({
                     'fill': rgb2hex(stroke),
                     'stroke': rgb2hex(stroke),
-                    'stroke-width': '1.0',
+                    'stroke-width': six.text_type(rcParams['hatch.linewidth']),
                     'stroke-linecap': 'butt',
                     'stroke-linejoin': 'miter'
                     })

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

@@ -32,6 +32,8 @@ patch.facecolor        : b
 patch.edgecolor        : k
 patch.antialiased      : True    # render patches in antialiased (no jaggies)
 
+hatch.linewidth        : 1.0
+
 hist.bins              : 10
 
 ### FONT

lib/matplotlib/rcsetup.py

@@ -870,6 +870,9 @@ def validate_animation_writer_path(p):
     'patch.facecolor':   ['#1f77b4', validate_color],  # blue (first color in color cycle)
     'patch.antialiased': [True, validate_bool],  # antialiased (no jaggies)
 
+    ## hatch props
+    'hatch.linewidth': [1.0, validate_float],
+
     ## Histogram properties
     'hist.bins': [10, validate_hist_bins],
 

matplotlibrc.template

@@ -109,6 +109,9 @@ backend      : $TEMPLATE_BACKEND
 #patch.edgecolor        : black
 #patch.antialiased      : True    # render patches in antialiased (no jaggies)
 
+### HATCHES
+#hatch.linewidth : 1.0
+
 ### Boxplot
 #boxplot.notch       : False
 #boxplot.vertical    : True

src/_backend_agg.h

@@ -363,7 +363,7 @@ RendererAgg::_draw_path(path_t &path, bool has_clippath, const facepair_t &face,
         hatch_path_trans_t hatch_path_trans(hatch_path, hatch_trans);
         hatch_path_curve_t hatch_path_curve(hatch_path_trans);
         hatch_path_stroke_t hatch_path_stroke(hatch_path_curve);
-        hatch_path_stroke.width(1.0);
+        hatch_path_stroke.width(points_to_pixels(gc.hatch_linewidth));
         hatch_path_stroke.line_cap(agg::square_cap);
 
         // Render the path into the hatch buffer

src/_backend_agg_basic_types.h

@@ -108,6 +108,7 @@ class GCAgg
     e_snap_mode snap_mode;
 
     py::PathIterator hatchpath;
+    double hatch_linewidth;
 
     SketchParams sketch;
 

src/py_converters.cpp

@@ -481,6 +481,7 @@ int convert_gcagg(PyObject *pygc, void *gcp)
           convert_from_method(pygc, "get_clip_path", &convert_clippath, &gc->clippath) &&
           convert_from_method(pygc, "get_snap", &convert_snap, &gc->snap_mode) &&
           convert_from_method(pygc, "get_hatch_path", &convert_path, &gc->hatchpath) &&
+          convert_from_method(pygc, "get_hatch_linewidth", &convert_double, &gc->hatch_linewidth) &&
           convert_from_method(pygc, "get_sketch_params", &convert_sketch_params, &gc->sketch))) {
         return 0;
     }