class Gruff::Dot

Graph with dots and labels along a vertical access see: 'Creating More Effective Graphs' by Robbins

Public Instance Methods

draw() click to toggle source
Calls superclass method Gruff::Base#draw
# File lib/gruff/dot.rb, line 9
def draw
  @has_left_labels = true
  super

  return unless @has_data

  # Setup spacing.
  #
  spacing_factor = 1.0

  @items_width = @graph_height / @column_count.to_f
  @item_width = @items_width * spacing_factor / @norm_data.size
  @d = @d.stroke_opacity 0.0
  padding = (@items_width * (1 - spacing_factor)) / 2

  @norm_data.each_with_index do |data_row, row_index|
    data_row[DATA_VALUES_INDEX].each_with_index do |data_point, point_index|
      x_pos = @graph_left + (data_point * @graph_width)
      y_pos = @graph_top + (@items_width * point_index) + padding + (@items_width.to_f/2.0).round

      if row_index == 0
        @d = @d.stroke(@marker_color)
        @d = @d.fill(@marker_color)
        @d = @d.stroke_width 1.0
        @d = @d.stroke_opacity 0.1
        @d = @d.fill_opacity 0.1
        @d = @d.line(@graph_left, y_pos, @graph_left + @graph_width, y_pos)
        @d = @d.fill_opacity 1
      end

      @d = @d.fill data_row[DATA_COLOR_INDEX]
      @d = @d.stroke('transparent')
      @d = @d.circle(x_pos, y_pos, x_pos + (@item_width.to_f/3.0).round, y_pos)

      draw_label(y_pos, point_index)
    end

  end

  @d.draw(@base_image)
end

Protected Instance Methods

draw_label(y_offset, index) click to toggle source

Draw on the Y axis instead of the X

# File lib/gruff/dot.rb, line 109
def draw_label(y_offset, index)
  if !@labels[index].nil? && @labels_seen[index].nil?
    @d.fill = @font_color
    @d.font = @font if @font
    @d.stroke = 'transparent'
    @d.font_weight = NormalWeight
    @d.pointsize = scale_fontsize(@marker_font_size)
    @d.gravity = EastGravity
    @d = @d.annotate_scaled(@base_image,
                            1, 1,
                            -@graph_left + LABEL_MARGIN * 2.0, y_offset,
                            @labels[index], @scale)
    @labels_seen[index] = 1
  end
end
draw_line_markers() click to toggle source

Instead of base class version, draws vertical background lines and label

# File lib/gruff/dot.rb, line 54
def draw_line_markers
  return if @hide_line_markers

  @d = @d.stroke_antialias false

  # Draw horizontal line markers and annotate with numbers
  @d = @d.stroke(@marker_color)
  @d = @d.stroke_width 1
  if @y_axis_increment
    increment = @y_axis_increment
    number_of_lines = (@spread / @y_axis_increment).to_i
  else
    # Try to use a number of horizontal lines that will come out even.
    #
    # TODO Do the same for larger numbers...100, 75, 50, 25
    if @marker_count.nil?
      (3..7).each do |lines|
        if @spread % lines == 0.0
          @marker_count = lines
          break
        end
      end
      @marker_count ||= 5
    end
    # TODO Round maximum marker value to a round number like 100, 0.1, 0.5, etc.
    @increment = (@spread > 0 && @marker_count > 0) ? significant(@spread / @marker_count) : 1

    number_of_lines = @marker_count
    increment = @increment
  end

  (0..number_of_lines).each do |index|
    marker_label = @minimum_value + index * increment
    x = @graph_left + (marker_label - @minimum_value) * @graph_width / @spread
    @d = @d.line(x, @graph_bottom, x, @graph_bottom + 0.5 * LABEL_MARGIN)

    unless @hide_line_numbers
      @d.fill = @font_color
      @d.font = @font if @font
      @d.stroke = 'transparent'
      @d.pointsize = scale_fontsize(@marker_font_size)
      @d.gravity = CenterGravity
      # TODO Center text over line
      @d = @d.annotate_scaled(@base_image,
                              0, 0, # Width of box to draw text in
                              x, @graph_bottom + (LABEL_MARGIN * 2.0), # Coordinates of text
                              label(marker_label, increment), @scale)
    end # unless
    @d = @d.stroke_antialias true
  end
end