comparison lib/SVG/Graph/Graph.rb @ 0:513646585e45

* Import Redmine trunk SVN rev 3859

+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