Class: Gruff::StackedBar

Inherits:
Base
  • Object
show all
Includes:
BarValueLabelMixin, StackedMixin
Defined in:
lib/gruff/stacked_bar.rb

Overview

Here’s how to set up a Gruff::StackedBar.

g = Gruff::StackedBar.new
g.title = 'StackedBar Graph'
g.data :Art, [0, 5, 8, 15]
g.data :Philosophy, [10, 3, 2, 8]
g.data :Science, [2, 15, 8, 11]
g.write('stacked_bar.png')

Direct Known Subclasses

AccumulatorBar

Constant Summary

Constants inherited from Base

Base::DEFAULT_MARGIN, Base::DEFAULT_TARGET_WIDTH, Base::LABEL_MARGIN, Base::LEGEND_MARGIN

Instance Attribute Summary collapse

Attributes inherited from Base

#bold_title, #bottom_margin, #center_labels_over_point, #colors, #font_color, #has_left_labels, #hide_legend, #hide_line_markers, #hide_line_numbers, #hide_title, #label_max_size, #label_stagger_height, #label_truncation_style, #labels, #left_margin, #legend_at_bottom, #legend_box_size, #legend_font_size, #legend_margin, #marker_color, #marker_font_size, #marker_shadow_color, #maximum_value, #minimum_value, #no_data_message, #right_margin, #sort, #sorted_drawing, #title, #title_font, #title_font_size, #title_margin, #top_margin, #use_data_label, #x_axis_increment, #x_axis_label, #y_axis_increment, #y_axis_label

Instance Method Summary collapse

Methods inherited from Base

#add_color, #data, #font=, #initialize, #margins=, #replace_colors, #theme=, #theme_37signals, #theme_greyscale, #theme_keynote, #theme_odeo, #theme_pastel, #theme_rails_keynote, #to_blob, #to_image, #write

Constructor Details

This class inherits a constructor from Gruff::Base

Instance Attribute Details

#bar_spacing=(value) ⇒ Object (writeonly)

Spacing factor applied between bars.



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# File 'lib/gruff/stacked_bar.rb', line 18

def bar_spacing=(value)
  @bar_spacing = value
end

#hide_labels=(value) ⇒ Object (writeonly)

Prevent drawing of column labels below a stacked bar graph. Default is false.



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# File 'lib/gruff/stacked_bar.rb', line 32

def hide_labels=(value)
  @hide_labels = value
end

#label_formatting=(value) ⇒ Object (writeonly)

Set the number output format for labels using sprintf. Default is “%.2f”.



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# File 'lib/gruff/stacked_bar.rb', line 25

def label_formatting=(value)
  @label_formatting = value
end

#segment_spacing=(value) ⇒ Object (writeonly)

Number of pixels between bar segments.



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# File 'lib/gruff/stacked_bar.rb', line 21

def segment_spacing=(value)
  @segment_spacing = value
end

#show_labels_for_bar_values=(value) ⇒ Object (writeonly)

Output the values for the bars on a bar graph. Default is false.



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# File 'lib/gruff/stacked_bar.rb', line 29

def show_labels_for_bar_values=(value)
  @show_labels_for_bar_values = value
end

Instance Method Details

#draw ⇒ Object

Draws a bar graph, but multiple sets are stacked on top of each other.



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# File 'lib/gruff/stacked_bar.rb', line 45

def draw
  calculate_maximum_by_stack
  super
  return unless data_given?

  # Setup spacing.
  #
  # Columns sit stacked.
  bar_width = @graph_width / column_count.to_f
  padding = (bar_width * (1 - @bar_spacing)) / 2

  height = Array.new(column_count, 0)
  bar_value_label = BarValueLabel.new(column_count, bar_width)

  store.norm_data.each_with_index do |data_row, row_index|
    data_row.points.each_with_index do |data_point, point_index|
      next if data_point == 0

      # Use incremented x and scaled y
      left_x = @graph_left + (bar_width * point_index) + padding
      left_y = @graph_top + (@graph_height -
                             data_point * @graph_height -
                             height[point_index]) + @segment_spacing
      right_x = left_x + bar_width * @bar_spacing
      right_y = @graph_top + @graph_height - height[point_index]

      # update the total height of the current stacked bar
      height[point_index] += (data_point * @graph_height)

      rect_renderer = Gruff::Renderer::Rectangle.new(color: data_row.color)
      rect_renderer.render(left_x, left_y, right_x, right_y)

      # Calculate center based on bar_width and current row
      label_center = left_x + bar_width * @bar_spacing / 2.0
      draw_label(label_center, point_index)

      bar_value_label.coordinates[point_index] = [left_x, left_y, right_x, right_y]
      bar_value_label.values[point_index] += store.data[row_index].points[point_index]
    end
  end

  if @show_labels_for_bar_values
    bar_value_label.prepare_rendering(@label_formatting) do |x, y, text|
      draw_value_label(x, y, text, true)
    end
  end
end