revamped graph calculation architecture

Author: v0dro

CONTRIBUTING.md

@@ -4,10 +4,8 @@
 Each Artist contains a `(abs_x, abs_y)` pair that denotes the absolute position of the 
 Artist on the canvas. For `Figure` and `Axes` this pair denotes the top left corner.
 
-During the data collection phase (anything before calling `draw`), all the co-ordinates
-exist in the form of ratios. The absolute co-ordinates are calculated during the draw
-phase. Therefore there should be no code except in the `draw` methods where actual
-co-ordinates are calcualted.
+The absolute co-ordinates are calculated during the draw phase. Therefore there 
+should be no code except in the `draw` methods where actual co-ordinates are calcualted.
 
 Varible naming conventions:
 * All values that are absolute values will be prefixed with `abs_`.

lib/rubyplot/artist/axes.rb

@@ -49,21 +49,28 @@ class Axes < Base
       attr_reader :label_stagger_height
       # FIXME: possibly disposable attrs
       attr_reader :title_caps_height
-      attr_reader :top_spacing
+      # Set true if title is to be hidden.
+      attr_accessor :hide_title
+      # Margin between the X axis and the bottom of the Axes artist.
+      attr_accessor :x_axis_margin
+      # Margin between the Y axis and the left of the Axes artist.
+      attr_accessor :y_axis_margin
 
       # @param figure [Rubyplot::Figure] Figure object to which this Axes belongs.
       def initialize figure
         @figure = figure
 
         @x_title = ''
         @y_title = ''
+        @x_axis_margin = 40.0
+        @y_axis_margin = 40.0
         @x_range = [nil, nil]
         @y_range = [nil, nil]
         @x_tick_count = :default
         @y_tick_count = :default
 
-        @origin = %i[default default]
-        @title = nil
+        @origin = [nil, nil]
+        @title = ""
         @title_shift = 0
         @title_margin = TITLE_MARGIN
         @text_font = :default
@@ -74,7 +81,7 @@ def initialize figure
         @x_ticks = {}
         @plots = []
 
-        @raw_rows = @width * (@height/@width)
+        @raw_rows = width * (height/width)
 
         @theme = Rubyplot::Themes::CLASSIC_WHITE
         @geometry = Rubyplot::MagickWrapper::Plot::Scatter::Geometry.new
@@ -84,10 +91,8 @@ def initialize figure
         @legend_font_size = 20.0
         @legend_margin = LEGEND_MARGIN
         @title_font_size = 36.0
-        @scale = @width / @geometry.raw_columns
         @backend = @figure.backend
-        @backend.scale(@scale)
-        setup_default_theme
+        #@backend.scale(@scale)
         @plot_colors = []
         @legends = []
         @lines = []
@@ -98,16 +103,13 @@ def initialize figure
 
       # Write an image to a file by communicating with the backend.
       def draw
-        setup_drawing
-        prepare_legend
-        prepare_xy_axes
-        prepare_title
-        @plots.each(&:draw)
-      end
-
-      # Set the dimensions in pixels of the graph. Format: "widthxheight". so "800x600".
-      def dim= dim_string
-        @width, @height = dim_string.split('x').map(&:to_f)
+        configure_title
+        calculate_xy_axes_origin
+        configure_xy_axes
+        # configure_legends
+        # configure_plotting_data
+        # actually_draw
+        # @plots.each(&:draw)
       end
 
       def scatter! *args, &block
@@ -150,21 +152,23 @@ def write file_name
 
       # Absolute X co-ordinate of the Axes. Top left corner.
       def abs_x
-        @figure.top_spacing * @figure.abs_height + @figure.abs_x
+        @figure.top_spacing * @figure.height + @figure.abs_x
       end
 
       # Absolute Y co-ordinate of the Axes. Top left corner.
       def abs_y
-        @figure.top_spacing * @figure.abs_height + @figure.abs_y
+        @figure.top_spacing * @figure.height + @figure.abs_y
       end
+      
       # Absolute width of the Axes in pixels.
-      def abs_width
-        (@figure.left_spacing + @figure.right_spacing) * @figure.abs_width
+      def width
+        (1 - (@figure.left_spacing + @figure.right_spacing)) * @figure.width
       end
 
       # Absolute height of the Axes in pixels.
-      def abs_height
-        (@figure.top_spacing + @figure.bottom_spacing) * @figure.abs_height
+      # FIXME: expand for multiple axes on same figure. width too.
+      def height
+        (1 - (@figure.top_spacing + @figure.bottom_spacing)) * @figure.height
       end
 
       private
@@ -186,15 +190,6 @@ def with_backend plot_type, *args
 
         plot
       end
-      
-      def prepare_xy_axes
-        @x_axis = Rubyplot::Artist::XAxis.new(
-          self, @x_title, @x_range[0], @x_range[1])
-        @y_axis = Rubyplot::Artist::YAxis.new(
-          self, @y_title, @y_range[0], @y_range[1])
-        @x_axis.draw
-        @y_axis.draw
-      end
 
       def prepare_title
         return if @geometry.hide_title || @title.nil?
@@ -207,7 +202,7 @@ def prepare_title
           width: @geometry.raw_columns,
           font: @font,
           color: @font_color,
-          pointsize: @title_font_size * @scale,
+          pointsize: @title_font_size,
           internal_label: "axes title."
         )
         @texts << t
@@ -218,24 +213,7 @@ def prepare_legend
         @legends = @plots.map(&:create_legend)
         @legends.each { |l| l.draw }
       end
-      
-      def setup_default_theme
-        defaults = {
-          marker_color: 'white',
-          font_color: 'black',
-          background_image: nil
-        }
-        @geometry.theme_options = defaults.merge Themes::CLASSIC_WHITE
-        @marker_color = @geometry.theme_options[:marker_color]
-        @font_color = @geometry.theme_options[:font_color] || @marker_color
-        @backend.set_base_image_gradient(
-          @geometry.theme_options[:background_colors][0],
-          @geometry.theme_options[:background_colors][1],
-          @width,
-          @height,
-          @geometry.theme_options[:background_direction])
-      end
-
+     
       # Calculates size of drawable area and generates normalized data.
       #
       # * line markers
@@ -271,14 +249,10 @@ def normalize
       # It calcuates the measurments in pixels to figure out the positioning
       # gap pixels of Legends, Labels and Titles from the picture edge. 
       def setup_graph_measurements
-        calculate_font_spaces
-        calculate_top_spacing
-        calculate_left_spacing
-        calculate_bottom_spacing
-        calculate_right_spacing
         @marker_caps_height = @backend.caps_height @font, @marker_font_size
         @title_caps_height = @geometry.hide_title || @title.nil? ? 0 :
-                               @backend.caps_height(@font, @title_font_size) * @title.lines.to_a.size
+                               @backend.caps_height(@font, @title_font_size) *
+                               @title.lines.to_a.size
         @legend_caps_height = @backend.caps_height @font, @legend_font_size
 
         # For now, the labels feature only focuses on the dot graph so it
@@ -337,10 +311,39 @@ def setup_graph_measurements
         @graph_height = @graph_bottom - @graph_top
       end
 
-      # Consider the various fonts that in use in this graph and calculate the
-      # ratio of the space that they will occupy w.r.t the Axes.
-      def calculate_font_spaces
-        
+      # Figure out the co-ordinates of the title text w.r.t Axes.
+      def configure_title
+        @title = Rubyplot::Artist::Text.new(
+          @title,
+          self,
+          abs_x: abs_x,
+          abs_y: abs_y,
+          font: @font,
+          color: @font_color,
+          pointsize: @title_font_size,
+          internal_label: "axes title."
+        )
+      end
+
+      def calculate_xy_axes_origin
+        @origin[0] = abs_x + @x_axis_margin
+        @origin[1] = abs_y + height - @y_axis_margin
+        puts "origin: #{@origin}"
+        puts "h: #{height}"
+        puts "w: #{width}"
+      end
+
+      # Figure out co-ordinatees of the XAxis and YAxis
+      def configure_xy_axes
+        @x_axis = Rubyplot::Artist::XAxis.new(
+          self, @x_title, @x_range[0], @x_range[1])
+        @x_axis.draw
+        # @y_axis = Rubyplot::Artist::YAxis.new(
+        #   self, @y_title, @y_range[0], @y_range[1])
+      end
+
+      # Figure out co-ordinates of the legends
+      def configure_legends
       end
 
       # Return a formatted string representing a number value that should be

lib/rubyplot/artist/axis/base.rb

@@ -2,22 +2,19 @@ module Rubyplot
   module Artist
     class Axis
       class Base
+        # Length in pixels of the arrow after the last major tick.
+        FINISH_ARROW_LENGTH = 10.0
+        
         attr_writer :label, :ticks, :major_ticks_count, :min_val, :max_val, :title
-        attr_reader :backend
+        attr_reader :abs_x1, :abs_x2, :abs_y1, :abs_y2, :backend
 
         def initialize axes, title, min_val, max_val
           @axes = axes
-          @title = title.empty? ? '' : title
-          @major_ticks_distance = 40.0
+          @title = title
           @min_val = min_val
           @max_val = max_val
           @backend = @axes.backend
         end
-
-        def draw
-          Rubyplot::Artist::Line2D.new(
-            self, x1: @x1, y1: @y1, x2: @x2, y2: @y2, stroke_width: 2.0).draw
-        end
       end # class Base
     end # class Axis
   end # class Artist

lib/rubyplot/artist/axis/x_axis.rb

@@ -5,52 +5,56 @@ module Artist
     class XAxis < Axis::Base
       def initialize(*)
         super
-        @x1 = @axes.graph_left
-        @y1 = @axes.graph_height + @axes.graph_top
-        @x2 = @axes.graph_width
-        @y2 = @axes.graph_height + @axes.graph_top
+        @abs_x1 = @axes.origin[0]
+        @abs_y1 = @axes.origin[1]
+        @abs_x2 = @axes.abs_x + @axes.width - @axes.y_axis_margin
+        @abs_y2 = @axes.origin[1]
+        @major_ticks_count = 5
+        @major_ticks_distance = (@abs_x2 - @abs_x1) / @major_ticks_count
         @x_ticks = []
-        @major_ticks_count = ((@x2 - @x1) / @major_ticks_distance).to_i
+        configure_axis_line
         populate_major_x_ticks
-        set_title
+        configure_title
       end
 
       def draw
-        super
+        @line.draw
         @x_ticks.each(&:draw)
-        @title.draw if @title
+        @title.draw
       end
 
       private
 
+      def configure_axis_line
+        @line = Rubyplot::Artist::Line2D.new(
+          self, abs_x1: @abs_x1, abs_y1: @abs_y1, abs_x2: @abs_x2, abs_y2: @abs_y2,
+          stroke_width: 1.0)
+      end
+      
       def populate_major_x_ticks
         value_distance = (@max_val - @min_val) / @major_ticks_count.to_f
         @major_ticks_count.times do |count|
           count += 1
           @x_ticks << Rubyplot::Artist::XTick.new(
             @axes,
-            x: count * @major_ticks_distance + @x1,
-            y: @y1,
+            abs_x: count * @major_ticks_distance + @abs_x1,
+            abs_y: @abs_y1,
             label: (count * value_distance),
             length: 6,
             label_distance: 10
           )
         end
       end
 
-      def set_title
-        if @title
-          @title = Rubyplot::Artist::Text.new(
-            @title,
-            self,
-            pointsize: @axes.marker_font_size * @axes.scale,
-            width: @axes.geometry.raw_columns,
-            height: 1.0,
-            y: @axes.graph_bottom + Artist::Axes::LABEL_MARGIN*2 + @axes.marker_caps_height,
-            x: @axes.graph_left + (@x2-@x1)/2.0,
-            gravity: :center
-          )
-        end
+      def configure_title
+        @title = Rubyplot::Artist::Text.new(
+          @title,
+          self,
+          pointsize: @axes.marker_font_size,
+          abs_y: @axes.origin[1],
+          abs_x: @axes.origin[0] + (@axes.abs_x + @axes.abs_y)/2,
+          gravity: :center
+        )
       end
     end # class XAxis
   end # class Artist