view lib/SVG/Graph/Graph.rb @ 922:ad295b270cd4 live

FIx #446: "non-utf8 paths in repositories blow up repo viewer and reposman" by ensuring the iconv conversion always happens even if source and dest are intended to be the same encoding

begin
  require 'zlib'
  @@__have_zlib = true
rescue
  @@__have_zlib = false
end

require 'rexml/document'

module SVG
  module Graph
    VERSION = '@ANT_VERSION@'

    # === Base object for generating SVG Graphs
    # 
    # == Synopsis
    #
    # This class is only used as a superclass of specialized charts.  Do not
    # attempt to use this class directly, unless creating a new chart type.
    #
    # For examples of how to subclass this class, see the existing specific
    # subclasses, such as SVG::Graph::Pie.
    #
    # == Examples
    #
    # For examples of how to use this package, see either the test files, or
    # the documentation for the specific class you want to use.
    #
    # * file:test/plot.rb
    # * file:test/single.rb
    # * file:test/test.rb
    # * file:test/timeseries.rb
    # 
    # == Description
    # 
    # This package should be used as a base for creating SVG graphs.
    #
    # == Acknowledgements
    #
    # Leo Lapworth for creating the SVG::TT::Graph package which this Ruby
    # port is based on.
    #
    # Stephen Morgan for creating the TT template and SVG.
    # 
    # == See
    #
    # * SVG::Graph::BarHorizontal
    # * SVG::Graph::Bar
    # * SVG::Graph::Line
    # * SVG::Graph::Pie
    # * SVG::Graph::Plot
    # * SVG::Graph::TimeSeries
    #
    # == Author
    #
    # Sean E. Russell <serATgermaneHYPHENsoftwareDOTcom>
    #
    # Copyright 2004 Sean E. Russell
    # This software is available under the Ruby license[LICENSE.txt]
    #
    class Graph
      include REXML

      # Initialize the graph object with the graph settings.  You won't
      # instantiate this class directly; see the subclass for options.
      # [width] 500
      # [height] 300
      # [show_x_guidelines] false
      # [show_y_guidelines] true
      # [show_data_values] true
      # [min_scale_value] 0
      # [show_x_labels] true
      # [stagger_x_labels] false
      # [rotate_x_labels] false
      # [step_x_labels] 1
      # [step_include_first_x_label] true
      # [show_y_labels] true
      # [rotate_y_labels] false
      # [scale_integers] false
      # [show_x_title] false
      # [x_title] 'X Field names'
      # [show_y_title] false
      # [y_title_text_direction] :bt
      # [y_title] 'Y Scale'
      # [show_graph_title] false
      # [graph_title] 'Graph Title'
      # [show_graph_subtitle] false
      # [graph_subtitle] 'Graph Sub Title'
      # [key] true,
      # [key_position] :right, # bottom or righ
      # [font_size] 12
      # [title_font_size] 16
      # [subtitle_font_size] 14
      # [x_label_font_size] 12
      # [x_title_font_size] 14
      # [y_label_font_size] 12
      # [y_title_font_size] 14
      # [key_font_size] 10
      # [no_css] false
      # [add_popups] false
      def initialize( config )
        @config = config

        self.top_align = self.top_font = self.right_align = self.right_font = 0

        init_with({
          :width                => 500,
          :height                => 300,
          :show_x_guidelines    => false,
          :show_y_guidelines    => true,
          :show_data_values     => true,

#          :min_scale_value      => 0,

          :show_x_labels        => true,
          :stagger_x_labels     => false,
          :rotate_x_labels      => false,
          :step_x_labels        => 1,
          :step_include_first_x_label => true,

          :show_y_labels        => true,
          :rotate_y_labels      => false,
          :stagger_y_labels     => false,
          :scale_integers       => false,

          :show_x_title         => false,
          :x_title              => 'X Field names',

          :show_y_title         => false,
          :y_title_text_direction => :bt,
          :y_title              => 'Y Scale',

          :show_graph_title      => false,
          :graph_title          => 'Graph Title',
          :show_graph_subtitle  => false,
          :graph_subtitle        => 'Graph Sub Title',
          :key                  => true, 
          :key_position          => :right, # bottom or right

          :font_size            =>12,
          :title_font_size      =>16,
          :subtitle_font_size   =>14,
          :x_label_font_size    =>12,
          :x_title_font_size    =>14,
          :y_label_font_size    =>12,
          :y_title_font_size    =>14,
          :key_font_size        =>10,
          
          :no_css               =>false,
          :add_popups           =>false,
        })

				set_defaults if respond_to? :set_defaults

        init_with config
      end

      
      # This method allows you do add data to the graph object.
      # It can be called several times to add more data sets in.
      #
      #   data_sales_02 = [12, 45, 21];
      #   
      #   graph.add_data({
      #     :data => data_sales_02,
      #     :title => 'Sales 2002'
      #   })
      def add_data conf
        @data = [] unless defined? @data

        if conf[:data] and conf[:data].kind_of? Array
          @data << conf
        else
          raise "No data provided by #{conf.inspect}"
        end
      end


      # This method removes all data from the object so that you can
      # reuse it to create a new graph but with the same config options.
      #
      #   graph.clear_data
      def clear_data 
        @data = []
      end


      # This method processes the template with the data and
      # config which has been set and returns the resulting SVG.
      #
      # This method will croak unless at least one data set has
      # been added to the graph object.
      #
      #   print graph.burn
      def burn
        raise "No data available" unless @data.size > 0
        
        calculations if respond_to? :calculations

        start_svg
        calculate_graph_dimensions
        @foreground = Element.new( "g" )
        draw_graph
        draw_titles
        draw_legend
        draw_data
        @graph.add_element( @foreground )
        style

        data = ""
        @doc.write( data, 0 )

        if @config[:compress]
          if @@__have_zlib
            inp, out = IO.pipe
            gz = Zlib::GzipWriter.new( out )
            gz.write data
            gz.close
            data = inp.read
          else
            data << "<!-- Ruby Zlib not available for SVGZ -->";
          end
        end
        
        return data
      end


      #   Set the height of the graph box, this is the total height
      #   of the SVG box created - not the graph it self which auto
      #   scales to fix the space.
      attr_accessor :height
      #   Set the width of the graph box, this is the total width
      #   of the SVG box created - not the graph it self which auto
      #   scales to fix the space.
      attr_accessor :width
      #   Set the path to an external stylesheet, set to '' if
      #   you want to revert back to using the defaut internal version.
      #
      #   To create an external stylesheet create a graph using the
      #   default internal version and copy the stylesheet section to
      #   an external file and edit from there.
      attr_accessor :style_sheet
      #   (Bool) Show the value of each element of data on the graph
      attr_accessor :show_data_values
      #   The point at which the Y axis starts, defaults to '0',
      #   if set to nil it will default to the minimum data value.
      attr_accessor :min_scale_value
      #   Whether to show labels on the X axis or not, defaults
      #   to true, set to false if you want to turn them off.
      attr_accessor :show_x_labels
      #   This puts the X labels at alternative levels so if they
      #   are long field names they will not overlap so easily.
      #   Default it false, to turn on set to true.
      attr_accessor :stagger_x_labels
      #   This puts the Y labels at alternative levels so if they
      #   are long field names they will not overlap so easily.
      #   Default it false, to turn on set to true.
      attr_accessor :stagger_y_labels
      #   This turns the X axis labels by 90 degrees.
      #   Default it false, to turn on set to true.
      attr_accessor :rotate_x_labels
      #   This turns the Y axis labels by 90 degrees.
      #   Default it false, to turn on set to true.
      attr_accessor :rotate_y_labels
      #   How many "steps" to use between displayed X axis labels,
      #   a step of one means display every label, a step of two results
      #   in every other label being displayed (label <gap> label <gap> label),
      #   a step of three results in every third label being displayed
      #   (label <gap> <gap> label <gap> <gap> label) and so on.
      attr_accessor :step_x_labels
      #   Whether to (when taking "steps" between X axis labels) step from 
      #   the first label (i.e. always include the first label) or step from
      #   the X axis origin (i.e. start with a gap if step_x_labels is greater
      #   than one).
      attr_accessor :step_include_first_x_label
      #   Whether to show labels on the Y axis or not, defaults
      #   to true, set to false if you want to turn them off.
      attr_accessor :show_y_labels
      #   Ensures only whole numbers are used as the scale divisions.
      #   Default it false, to turn on set to true. This has no effect if 
      #   scale divisions are less than 1.
      attr_accessor :scale_integers
      #   This defines the gap between markers on the Y axis,
      #   default is a 10th of the max_value, e.g. you will have
      #   10 markers on the Y axis. NOTE: do not set this too
      #   low - you are limited to 999 markers, after that the
      #   graph won't generate.
      attr_accessor :scale_divisions
      #   Whether to show the title under the X axis labels,
      #   default is false, set to true to show.
      attr_accessor :show_x_title
      #   What the title under X axis should be, e.g. 'Months'.
      attr_accessor :x_title
      #   Whether to show the title under the Y axis labels,
      #   default is false, set to true to show.
      attr_accessor :show_y_title
      #   Aligns writing mode for Y axis label. 
      #   Defaults to :bt (Bottom to Top).
      #   Change to :tb (Top to Bottom) to reverse.
      attr_accessor :y_title_text_direction
      #   What the title under Y axis should be, e.g. 'Sales in thousands'.
      attr_accessor :y_title
      #   Whether to show a title on the graph, defaults
      #   to false, set to true to show.
      attr_accessor :show_graph_title
      #   What the title on the graph should be.
      attr_accessor :graph_title
      #   Whether to show a subtitle on the graph, defaults
      #   to false, set to true to show.
      attr_accessor :show_graph_subtitle
      #   What the subtitle on the graph should be.
      attr_accessor :graph_subtitle
      #   Whether to show a key, defaults to false, set to
      #   true if you want to show it.
      attr_accessor :key
      #   Where the key should be positioned, defaults to
      #   :right, set to :bottom if you want to move it.
      attr_accessor :key_position
      # Set the font size (in points) of the data point labels
      attr_accessor :font_size
      # Set the font size of the X axis labels
      attr_accessor :x_label_font_size
      # Set the font size of the X axis title
      attr_accessor :x_title_font_size
      # Set the font size of the Y axis labels
      attr_accessor :y_label_font_size
      # Set the font size of the Y axis title
      attr_accessor :y_title_font_size
      # Set the title font size
      attr_accessor :title_font_size
      # Set the subtitle font size
      attr_accessor :subtitle_font_size
      # Set the key font size
      attr_accessor :key_font_size
      # Show guidelines for the X axis
      attr_accessor :show_x_guidelines
      # Show guidelines for the Y axis
      attr_accessor :show_y_guidelines
      # Do not use CSS if set to true.  Many SVG viewers do not support CSS, but
      # not using CSS can result in larger SVGs as well as making it impossible to
      # change colors after the chart is generated.  Defaults to false.
      attr_accessor :no_css
      # Add popups for the data points on some graphs
      attr_accessor :add_popups


      protected

      def sort( *arrys )
        sort_multiple( arrys )
      end

      # Overwrite configuration options with supplied options.  Used
      # by subclasses.
      def init_with config
        config.each { |key, value|
          self.send((key.to_s+"=").to_sym, value ) if respond_to? key.to_sym
        }
      end

      attr_accessor :top_align, :top_font, :right_align, :right_font

      KEY_BOX_SIZE = 12

      # Override this (and call super) to change the margin to the left
      # of the plot area.  Results in @border_left being set.
      def calculate_left_margin
        @border_left = 7
        # Check for Y labels
        max_y_label_height_px = rotate_y_labels ? 
          y_label_font_size :
          get_y_labels.max{|a,b| 
            a.to_s.length<=>b.to_s.length
          }.to_s.length * y_label_font_size * 0.6
        @border_left += max_y_label_height_px if show_y_labels
        @border_left += max_y_label_height_px + 10 if stagger_y_labels
        @border_left += y_title_font_size + 5 if show_y_title
      end


      # Calculates the width of the widest Y label.  This will be the
      # character height if the Y labels are rotated
      def max_y_label_width_px
        return font_size if rotate_y_labels
      end


      # Override this (and call super) to change the margin to the right
      # of the plot area.  Results in @border_right being set.
      def calculate_right_margin
        @border_right = 7
        if key and key_position == :right
          val = keys.max { |a,b| a.length <=> b.length }
          @border_right += val.length * key_font_size * 0.6 
          @border_right += KEY_BOX_SIZE
          @border_right += 10    # Some padding around the box
        end
      end


      # Override this (and call super) to change the margin to the top
      # of the plot area.  Results in @border_top being set.
      def calculate_top_margin
        @border_top = 5
        @border_top += title_font_size if show_graph_title
        @border_top += 5
        @border_top += subtitle_font_size if show_graph_subtitle
      end


      # Adds pop-up point information to a graph.
      def add_popup( x, y, label )
        txt_width = label.length * font_size * 0.6 + 10
        tx = (x+txt_width > width ? x-5 : x+5)
        t = @foreground.add_element( "text", {
          "x" => tx.to_s,
          "y" => (y - font_size).to_s,
          "visibility" => "hidden",
        })
        t.attributes["style"] = "fill: #000; "+
          (x+txt_width > width ? "text-anchor: end;" : "text-anchor: start;")
        t.text = label.to_s
        t.attributes["id"] = t.object_id.to_s

        @foreground.add_element( "circle", {
          "cx" => x.to_s,
          "cy" => y.to_s,
          "r" => "10",
          "style" => "opacity: 0",
          "onmouseover" => 
            "document.getElementById(#{t.object_id}).setAttribute('visibility', 'visible' )",
          "onmouseout" => 
            "document.getElementById(#{t.object_id}).setAttribute('visibility', 'hidden' )",
        })

      end

      
      # Override this (and call super) to change the margin to the bottom
      # of the plot area.  Results in @border_bottom being set.
      def calculate_bottom_margin
        @border_bottom = 7
        if key and key_position == :bottom
          @border_bottom += @data.size * (font_size + 5)
          @border_bottom += 10
        end
        if show_x_labels
		  max_x_label_height_px = (not rotate_x_labels) ? 
            x_label_font_size :
            get_x_labels.max{|a,b| 
              a.to_s.length<=>b.to_s.length
            }.to_s.length * x_label_font_size * 0.6
          @border_bottom += max_x_label_height_px
          @border_bottom += max_x_label_height_px + 10 if stagger_x_labels
        end
        @border_bottom += x_title_font_size + 5 if show_x_title
      end


      # Draws the background, axis, and labels.
      def draw_graph
        @graph = @root.add_element( "g", {
          "transform" => "translate( #@border_left #@border_top )"
        })

        # Background
        @graph.add_element( "rect", {
          "x" => "0",
          "y" => "0",
          "width" => @graph_width.to_s,
          "height" => @graph_height.to_s,
          "class" => "graphBackground"
        })

        # Axis
        @graph.add_element( "path", {
          "d" => "M 0 0 v#@graph_height",
          "class" => "axis",
          "id" => "xAxis"
        })
        @graph.add_element( "path", {
          "d" => "M 0 #@graph_height h#@graph_width",
          "class" => "axis",
          "id" => "yAxis"
        })

        draw_x_labels
        draw_y_labels
      end


      # Where in the X area the label is drawn
      # Centered in the field, should be width/2.  Start, 0.
      def x_label_offset( width )
        0
      end

      def make_datapoint_text( x, y, value, style="" )
        if show_data_values
          @foreground.add_element( "text", {
            "x" => x.to_s,
            "y" => y.to_s,
            "class" => "dataPointLabel",
            "style" => "#{style} stroke: #fff; stroke-width: 2;"
          }).text = value.to_s
          text = @foreground.add_element( "text", {
            "x" => x.to_s,
            "y" => y.to_s,
            "class" => "dataPointLabel"
          })
          text.text = value.to_s
          text.attributes["style"] = style if style.length > 0
        end
      end


      # Draws the X axis labels
      def draw_x_labels
        stagger = x_label_font_size + 5
        if show_x_labels
          label_width = field_width

          count = 0
          for label in get_x_labels
            if step_include_first_x_label == true then
              step = count % step_x_labels
            else
              step = (count + 1) % step_x_labels
            end

            if step == 0 then
              text = @graph.add_element( "text" )
              text.attributes["class"] = "xAxisLabels"
              text.text = label.to_s

              x = count * label_width + x_label_offset( label_width )
              y = @graph_height + x_label_font_size + 3
              t = 0 - (font_size / 2)

              if stagger_x_labels and count % 2 == 1
                y += stagger
                @graph.add_element( "path", {
                  "d" => "M#{x} #@graph_height v#{stagger}",
                  "class" => "staggerGuideLine"
                })
              end

              text.attributes["x"] = x.to_s
              text.attributes["y"] = y.to_s
              if rotate_x_labels
                text.attributes["transform"] = 
                  "rotate( 90 #{x} #{y-x_label_font_size} )"+
                  " translate( 0 -#{x_label_font_size/4} )"
                text.attributes["style"] = "text-anchor: start"
              else
                text.attributes["style"] = "text-anchor: middle"
              end
            end

            draw_x_guidelines( label_width, count ) if show_x_guidelines
            count += 1
          end
        end
      end


      # Where in the Y area the label is drawn
      # Centered in the field, should be width/2.  Start, 0.
      def y_label_offset( height )
        0
      end


      def field_width
        (@graph_width.to_f - font_size*2*right_font) /
           (get_x_labels.length - right_align)
      end


      def field_height
        (@graph_height.to_f - font_size*2*top_font) /
           (get_y_labels.length - top_align)
      end


      # Draws the Y axis labels
      def draw_y_labels
        stagger = y_label_font_size + 5
        if show_y_labels
          label_height = field_height

          count = 0
          y_offset = @graph_height + y_label_offset( label_height )
          y_offset += font_size/1.2 unless rotate_y_labels
          for label in get_y_labels
            y = y_offset - (label_height * count)
            x = rotate_y_labels ? 0 : -3

            if stagger_y_labels and count % 2 == 1
              x -= stagger
              @graph.add_element( "path", {
                "d" => "M#{x} #{y} h#{stagger}",
                "class" => "staggerGuideLine"
              })
            end

            text = @graph.add_element( "text", {
              "x" => x.to_s,
              "y" => y.to_s,
              "class" => "yAxisLabels"
            })
            text.text = label.to_s
            if rotate_y_labels
              text.attributes["transform"] = "translate( -#{font_size} 0 ) "+
                "rotate( 90 #{x} #{y} ) "
              text.attributes["style"] = "text-anchor: middle"
            else
              text.attributes["y"] = (y - (y_label_font_size/2)).to_s
              text.attributes["style"] = "text-anchor: end"
            end
            draw_y_guidelines( label_height, count ) if show_y_guidelines
            count += 1
          end
        end
      end


      # Draws the X axis guidelines
      def draw_x_guidelines( label_height, count )
        if count != 0
          @graph.add_element( "path", {
            "d" => "M#{label_height*count} 0 v#@graph_height",
            "class" => "guideLines"
          })
        end
      end


      # Draws the Y axis guidelines
      def draw_y_guidelines( label_height, count )
        if count != 0
          @graph.add_element( "path", {
            "d" => "M0 #{@graph_height-(label_height*count)} h#@graph_width",
            "class" => "guideLines"
          })
        end
      end


      # Draws the graph title and subtitle
      def draw_titles
        if show_graph_title
          @root.add_element( "text", {
            "x" => (width / 2).to_s,
            "y" => (title_font_size).to_s,
            "class" => "mainTitle"
          }).text = graph_title.to_s
        end

        if show_graph_subtitle
          y_subtitle = show_graph_title ? 
            title_font_size + 10 :
            subtitle_font_size
          @root.add_element("text", {
            "x" => (width / 2).to_s,
            "y" => (y_subtitle).to_s,
            "class" => "subTitle"
          }).text = graph_subtitle.to_s
        end

        if show_x_title
          y = @graph_height + @border_top + x_title_font_size
          if show_x_labels
            y += x_label_font_size + 5 if stagger_x_labels
            y += x_label_font_size + 5
          end
          x = width / 2

          @root.add_element("text", {
            "x" => x.to_s,
            "y" => y.to_s,
            "class" => "xAxisTitle",
          }).text = x_title.to_s
        end

        if show_y_title
          x = y_title_font_size + (y_title_text_direction==:bt ? 3 : -3)
          y = height / 2

          text = @root.add_element("text", {
            "x" => x.to_s,
            "y" => y.to_s,
            "class" => "yAxisTitle",
          })
          text.text = y_title.to_s
          if y_title_text_direction == :bt
            text.attributes["transform"] = "rotate( -90, #{x}, #{y} )"
          else
            text.attributes["transform"] = "rotate( 90, #{x}, #{y} )"
          end
        end
      end

      def keys 
        return @data.collect{ |d| d[:title] }
      end

      # Draws the legend on the graph
      def draw_legend
        if key
          group = @root.add_element( "g" )

          key_count = 0
          for key_name in keys
            y_offset = (KEY_BOX_SIZE * key_count) + (key_count * 5)
            group.add_element( "rect", {
              "x" => 0.to_s,
              "y" => y_offset.to_s,
              "width" => KEY_BOX_SIZE.to_s,
              "height" => KEY_BOX_SIZE.to_s,
              "class" => "key#{key_count+1}"
            })
            group.add_element( "text", {
              "x" => (KEY_BOX_SIZE + 5).to_s,
              "y" => (y_offset + KEY_BOX_SIZE).to_s,
              "class" => "keyText"
            }).text = key_name.to_s
            key_count += 1
          end

          case key_position
          when :right
            x_offset = @graph_width + @border_left + 10
            y_offset = @border_top + 20
          when :bottom
            x_offset = @border_left + 20
            y_offset = @border_top + @graph_height + 5
            if show_x_labels
			  max_x_label_height_px = (not rotate_x_labels) ? 
				x_label_font_size :
				get_x_labels.max{|a,b| 
				  a.to_s.length<=>b.to_s.length
				}.to_s.length * x_label_font_size * 0.6
                x_label_font_size
              y_offset += max_x_label_height_px
              y_offset += max_x_label_height_px + 5 if stagger_x_labels
            end
            y_offset += x_title_font_size + 5 if show_x_title
          end
          group.attributes["transform"] = "translate(#{x_offset} #{y_offset})"
        end
      end


      private

      def sort_multiple( arrys, lo=0, hi=arrys[0].length-1 )
        if lo < hi
          p = partition(arrys,lo,hi)
          sort_multiple(arrys, lo, p-1)
          sort_multiple(arrys, p+1, hi)
        end
        arrys 
      end

      def partition( arrys, lo, hi )
        p = arrys[0][lo]
        l = lo
        z = lo+1
        while z <= hi
          if arrys[0][z] < p
            l += 1
            arrys.each { |arry| arry[z], arry[l] = arry[l], arry[z] }
          end
          z += 1
        end
        arrys.each { |arry| arry[lo], arry[l] = arry[l], arry[lo] }
        l
      end

      def style
        if no_css
          styles = parse_css
          @root.elements.each("//*[@class]") { |el|
            cl = el.attributes["class"]
            style = styles[cl]
            style += el.attributes["style"] if el.attributes["style"]
            el.attributes["style"] = style
          }
        end
      end

      def parse_css
        css = get_style
        rv = {}
        while css =~ /^(\.(\w+)(?:\s*,\s*\.\w+)*)\s*\{/m
          names_orig = names = $1
          css = $'
          css =~ /([^}]+)\}/m
          content = $1
          css = $'

          nms = []
          while names =~ /^\s*,?\s*\.(\w+)/
            nms << $1
            names = $'
          end

          content = content.tr( "\n\t", " ")
          for name in nms
            current = rv[name]
            current = current ? current+"; "+content : content
            rv[name] = current.strip.squeeze(" ")
          end
        end
        return rv
      end


      # Override and place code to add defs here
      def add_defs defs
      end


      def start_svg
        # Base document
        @doc = Document.new
        @doc << XMLDecl.new
        @doc << DocType.new( %q{svg PUBLIC "-//W3C//DTD SVG 1.0//EN" } +
          %q{"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd"} )
        if style_sheet && style_sheet != ''
          @doc << Instruction.new( "xml-stylesheet",
            %Q{href="#{style_sheet}" type="text/css"} )
        end
        @root = @doc.add_element( "svg", {
          "width" => width.to_s,
          "height" => height.to_s,
          "viewBox" => "0 0 #{width} #{height}",
          "xmlns" => "http://www.w3.org/2000/svg",
          "xmlns:xlink" => "http://www.w3.org/1999/xlink",
          "xmlns:a3" => "http://ns.adobe.com/AdobeSVGViewerExtensions/3.0/",
          "a3:scriptImplementation" => "Adobe"
        })
        @root << Comment.new( " "+"\\"*66 )
        @root << Comment.new( " Created with SVG::Graph " )
        @root << Comment.new( " SVG::Graph by Sean E. Russell " )
        @root << Comment.new( " Losely based on SVG::TT::Graph for Perl by"+
        " Leo Lapworth & Stephan Morgan " )
        @root << Comment.new( " "+"/"*66 )

        defs = @root.add_element( "defs" )
        add_defs defs
        if not(style_sheet && style_sheet != '') and !no_css
          @root << Comment.new(" include default stylesheet if none specified ")
          style = defs.add_element( "style", {"type"=>"text/css"} )
          style << CData.new( get_style )
        end

        @root << Comment.new( "SVG Background" )
        @root.add_element( "rect", {
          "width" => width.to_s,
          "height" => height.to_s,
          "x" => "0",
          "y" => "0",
          "class" => "svgBackground"
        })
      end


      def calculate_graph_dimensions
        calculate_left_margin
        calculate_right_margin
        calculate_bottom_margin
        calculate_top_margin
        @graph_width = width - @border_left - @border_right
        @graph_height = height - @border_top - @border_bottom
      end

      def get_style
        return <<EOL
/* Copy from here for external style sheet */
.svgBackground{
  fill:#ffffff;
}
.graphBackground{
  fill:#f0f0f0;
}

/* graphs titles */
.mainTitle{
  text-anchor: middle;
  fill: #000000;
  font-size: #{title_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}
.subTitle{
  text-anchor: middle;
  fill: #999999;
  font-size: #{subtitle_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.axis{
  stroke: #000000;
  stroke-width: 1px;
}

.guideLines{
  stroke: #666666;
  stroke-width: 1px;
  stroke-dasharray: 5 5;
}

.xAxisLabels{
  text-anchor: middle;
  fill: #000000;
  font-size: #{x_label_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.yAxisLabels{
  text-anchor: end;
  fill: #000000;
  font-size: #{y_label_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.xAxisTitle{
  text-anchor: middle;
  fill: #ff0000;
  font-size: #{x_title_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.yAxisTitle{
  fill: #ff0000;
  text-anchor: middle;
  font-size: #{y_title_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.dataPointLabel{
  fill: #000000;
  text-anchor:middle;
  font-size: 10px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}

.staggerGuideLine{
  fill: none;
  stroke: #000000;
  stroke-width: 0.5px;  
}

#{get_css}

.keyText{
  fill: #000000;
  text-anchor:start;
  font-size: #{key_font_size}px;
  font-family: "Arial", sans-serif;
  font-weight: normal;
}
/* End copy for external style sheet */
EOL
      end

    end
  end
end