Add legend_at_bottom_columns option to specify number of columns in l…

…egend when at bottom. Fixes #157

demo/moulinrouge/tests.py

@@ -511,9 +511,10 @@ def test_pie_serie_radius():
     @app.route('/test/half_pie')
     def test_half_pie():
         pie = Pie(half_pie=True)
-        for i in range(10):
+        for i in range(100):
             pie.add(str(i), i, inner_radius=.1)
-
+        pie.legend_at_bottom = True
+        pie.legend_at_bottom_columns = 4
         return pie.render_response()
 
     @app.route('/test/legend_at_bottom/<chart>')

pygal/config.py

@@ -221,6 +221,9 @@ class Config(CommonConfig):
     legend_at_bottom = Key(
         False, bool, "Look", "Set to true to position legend at bottom")
 
+    legend_at_bottom_columns = Key(
+        None, int, "Look", "Set to true to position legend at bottom")
+
     legend_box_size = Key(
         12, int, "Look", "Size of legend boxes")
 

pygal/graph/base.py

@@ -27,7 +27,7 @@
     get_text_box, get_texts_box, cut, rad, humanize, truncate, split_title)
 from pygal.svg import Svg
 from pygal.util import cached_property, majorize
-from math import sin, cos, sqrt
+from math import sin, cos, sqrt, ceil
 
 
 class BaseGraph(object):
@@ -93,8 +93,11 @@ def _compute_margin(self):
                     self.legend_font_size)
                 if self.legend_at_bottom:
                     h_max = max(h, self.legend_box_size)
+                    cols = (self._order // self.legend_at_bottom_columns
+                            if self.legend_at_bottom_columns
+                            else ceil(sqrt(self._order)) or 1)
                     self.margin.bottom += self.spacing + h_max * round(
-                        sqrt(self._order) - 1) * 1.5 + h_max
+                        cols - 1) * 1.5 + h_max
                 else:
                     if series_group is self.series:
                         legend_width = self.spacing + w + self.legend_box_size

pygal/graph/graph.py

@@ -279,7 +279,8 @@ def _legend(self):
             y = (self.margin.top + self.view.height +
                  self._x_title_height +
                  self._x_labels_height + self.spacing)
-            cols = ceil(sqrt(self._order)) or 1
+            cols = self.legend_at_bottom_columns or ceil(
+                sqrt(self._order)) or 1
 
             if not truncation:
                 available_space = self.view.width / cols - (