projects.mako.cc - selectricity/blob - lib/gruff-0.2.8/lib/gruff/stacked_bar.rb

   1
   2 require File.dirname(__FILE__) + '/base'
   3
   4 class Gruff::StackedBar < Gruff::Base
   5
   6     # Draws a bar graph, but multiple sets are stacked on top of each other.
   7     def draw
   8       get_maximum_by_stack
   9       super
  10       return unless @has_data
  11
  12       # Setup spacing.
  13       #
  14       # Columns sit stacked.
  15       spacing_factor = 0.9
  16       @bar_width = @graph_width / @column_count.to_f
  17
  18       @d = @d.stroke_opacity 0.0
  19
  20       height = Array.new(@column_count, 0)
  21
  22       @norm_data.each_with_index do |data_row, row_index|
  23         @d = @d.fill data_row[DATA_COLOR_INDEX]
  24
  25         data_row[1].each_with_index do |data_point, point_index|
  26           # Use incremented x and scaled y
  27           left_x = @graph_left + (@bar_width * point_index)
  28           left_y = @graph_top + (@graph_height -
  29                                  data_point * @graph_height -
  30                                  height[point_index]) + 1
  31           right_x = left_x + @bar_width * spacing_factor
  32           right_y = @graph_top + @graph_height - height[point_index] - 1
  33
  34           # update the total height of the current stacked bar
  35           height[point_index] += (data_point * @graph_height - 2)
  36
  37           @d = @d.rectangle(left_x, left_y, right_x, right_y)
  38
  39           # Calculate center based on bar_width and current row
  40           label_center = @graph_left + (@bar_width * point_index) + (@bar_width * spacing_factor / 2.0)
  41           draw_label(label_center, point_index)
  42         end
  43
  44       end
  45
  46       @d.draw(@base_image)
  47     end
  48
  49 end