Add parametric styles

demo/moulinrouge/__init__.py

@@ -21,7 +21,7 @@ import pygal
 from pygal.config import Config
 from pygal.util import cut
 from pygal.graph import CHARTS_NAMES
-from pygal.style import styles
+from pygal.style import styles, parametric_styles
 from base64 import (
     urlsafe_b64encode as b64encode,
     urlsafe_b64decode as b64decode)
@@ -84,7 +84,9 @@ def create_app():
     @app.route("/")
     def index():
         return render_template(
-            'index.jinja2', styles=styles,
+            'index.jinja2', styles=styles, parametric_styles=parametric_styles,
+            parametric_colors=(
+                '#ff5995', '#b6e354', '#feed6c', '#8cedff', '#9e6ffe'),
             links=links, charts_name=CHARTS_NAMES)
 
     @app.route("/svg/<type>/<series>/<config>")
@@ -95,19 +97,30 @@ def create_app():
         return graph.render_response()
 
     @app.route("/sparkline/<style>")
-    def sparkline(style):
-        line = pygal.Line(style=styles[style], pretty_print=True)
+    @app.route("/sparkline/parameric/<style>/<color>")
+    def sparkline(style, color=None):
+        if color is None:
+            style = styles[style]
+        else:
+            style = parametric_styles[style](color)
+
+        line = pygal.Line(style=style, pretty_print=True)
         line.add('_', [random.randrange(0, 10) for _ in range(25)])
         return Response(
             line.render_sparkline(height=40), mimetype='image/svg+xml')
 
     @app.route("/all")
-    @app.route("/all/style=<style>")
+    @app.route("/all/<style>")
+    @app.route("/all/<style>/<color>")
     @app.route("/all/interpolate=<interpolate>")
-    def all(style='default', interpolate=None):
+    def all(style='default', color=None, interpolate=None):
         width, height = 600, 400
         data = random.randrange(1, 10)
         order = random.randrange(1, 10)
+        if color is None:
+            style = styles[style]
+        else:
+            style = parametric_styles[style](color)
         xy_series = _random(data, order)
         other_series = []
         for title, values in xy_series:
@@ -121,7 +134,7 @@ def create_app():
         config.fill = bool(random.randrange(0, 2))
         config.human_readable = True
         config.interpolate = interpolate
-        config.style = styles[style]
+        config.style = style
         config.x_labels = [random_label() for i in range(data)]
         svgs = []
         for chart in pygal.CHARTS:

demo/moulinrouge/templates/index.jinja2

@@ -3,12 +3,22 @@
 {% block section %}
   <h1>Moulin Rouge</h1>
   <ul>
+    <li>Styles</li>
     {% for style in styles %}
       <li>
         <embed src="{{ url_for('sparkline', style=style) }}" type="image/svg+xml" />
         <a href="{{ url_for('all', style=style) }}">{{ style | title }}</a>
       </li>
     {% endfor %}
+    <li>Parametric Styles</li>
+    {% for color in parametric_colors %}
+      <li><embed src="{{ url_for('sparkline', style='RotateStyle', color=color) }}" type="image/svg+xml" /></li>
+      {% for style in parametric_styles %}
+        <li>
+          <a href="{{ url_for('all', style=style, color=color) }}">{{ style }} for {{ color }}</a>
+        </li>
+      {% endfor %}
+    {% endfor %}
   </ul>
   <a href="{{ url_for('interpolation') }}">Interpolation</a>
   <a href="{{ url_for('rotation') }}">Rotations test</a>

pygal/style.py

@@ -21,6 +21,8 @@ Charts styling
 """
 from __future__ import division
 from pygal.util import cycle_fill
+from pygal import colors
+import sys
 
 
 class Style(object):
@@ -130,3 +132,30 @@ styles = {'default': DefaultStyle,
           'clean': CleanStyle,
           'dark_solarized': DarkSolarizedStyle,
           'light_solarized': LightSolarizedStyle}
+
+
+parametric_styles = {}
+for op in ('lighten', 'darken', 'saturate', 'desaturate', 'rotate'):
+    name = op.capitalize() + 'Style'
+
+    def get_style_for(op_):
+        operation = getattr(colors, op_)
+
+        def parametric_style(color, step=10, max_=None, **kwargs):
+            if max_ is None:
+                max__ = 50 if op_ != 'rotate' else 360
+            else:
+                max__ = max_
+
+            def modifier(index):
+                percent = max__ * index / (step - 1)
+                return operation(color, percent)
+
+            colors = list(map(modifier, range(0, max(2, step))))
+            return Style(colors=colors, **kwargs)
+
+        return parametric_style
+
+    style = get_style_for(op)
+    parametric_styles[name] = style
+    setattr(sys.modules[__name__], name, style)