From d2839f58394117b57e47dd765c388005808295ed Mon Sep 17 00:00:00 2001
From: arzoo14 <arzoopprajapati11@gmail.com>
Date: Thu, 18 Apr 2019 00:40:22 +0530
Subject: [PATCH] coding_work

---
 lib/rubyplot/artist/axes.rb             | 116 ++++++++++++++++++++++--
 lib/rubyplot/artist/axis.rb             |   2 +
 lib/rubyplot/artist/axis/x_axis.rb      |   2 +-
 lib/rubyplot/artist/axis/x_dash_axis.rb |  35 +++++++
 lib/rubyplot/artist/axis/y_axis.rb      |   2 +-
 lib/rubyplot/artist/axis/y_dash_axis.rb |  40 ++++++++
 lib/rubyplot/artist/plot/line.rb        |   5 +-
 lib/rubyplot/artist/plot/multi_bars.rb  |   4 +-
 lib/rubyplot/artist/tick.rb             |   2 +
 lib/rubyplot/artist/tick/x_dash_tick.rb |  27 ++++++
 lib/rubyplot/artist/tick/y_dash_tick.rb |  26 ++++++
 lib/rubyplot/artist/tick/y_tick.rb      |   4 +-
 lib/rubyplot/backend/base.rb            |  10 ++
 lib/rubyplot/backend/gr_wrapper.rb      |  94 +++++++++++++++++++
 14 files changed, 353 insertions(+), 16 deletions(-)
 create mode 100644 lib/rubyplot/artist/axis/x_dash_axis.rb
 create mode 100644 lib/rubyplot/artist/axis/y_dash_axis.rb
 create mode 100644 lib/rubyplot/artist/tick/x_dash_tick.rb
 create mode 100644 lib/rubyplot/artist/tick/y_dash_tick.rb
 create mode 100644 lib/rubyplot/backend/base.rb
 create mode 100644 lib/rubyplot/backend/gr_wrapper.rb

diff --git a/lib/rubyplot/artist/axes.rb b/lib/rubyplot/artist/axes.rb
index d2710c2..f91f9e6 100644
--- a/lib/rubyplot/artist/axes.rb
+++ b/lib/rubyplot/artist/axes.rb
@@ -19,18 +19,32 @@ class Axes < Base
       attr_reader :label_stagger_height
       # Rubyplot::Artist::XAxis object.
       attr_reader :x_axis
+      # Rubyplot::Artist::XDashAxis object.
+      attr_reader :x_dash_axis
+
       # Rubyplot::Artist::YAxis object.
       attr_reader :y_axis
+# Rubyplot::Artist::YDASHAxis object.
+      attr_reader :y_dash_axis
+
       # Array of X ticks.
       attr_reader :x_ticks
+      # Array of X dash ticks.
+      attr_reader :x_dash_ticks
       # Array of Y ticks.
       attr_reader :y_ticks
+      # Array of Y dash ticks.
+      attr_reader :y_dash_ticks
       # Array denoting co-ordinates in pixels of the origin of X and Y axes.
       attr_reader :origin
       # Number of X ticks.
       attr_accessor :num_x_ticks
+      # Number of X dash ticks.
+      attr_accessor :num_x_dash_ticks
       # Number of Y ticks.
       attr_accessor :num_y_ticks
+      # Number of Y dash ticks.
+      attr_accessor :num_y_dash_ticks
       # Position of the legend box.
       attr_accessor :legend_box_position
       # Set true if title is to be hidden.
@@ -41,6 +55,10 @@ class Axes < Base
       attr_accessor :y_axis_margin
       # Range of X axis.
       attr_accessor :x_range
+      # Range of X dash axis.
+      attr_accessor :x_dash_range
+      # Range of Y dash axis.
+      attr_accessor :y_dash_range
       # Range of Y axis.
       attr_accessor :y_range, :grid, :bounding_box, :title_shift
       # Main title for this Axes.
@@ -55,7 +73,9 @@ def initialize(figure)
         @x_axis_margin = 40.0
         @y_axis_margin = 40.0
         @x_range = [nil, nil]
+	@x_dash_range = [nil, nil]
         @y_range = [nil, nil]
+	@y_dash_range = [nil, nil]
         @title = ''
         @title_shift = 0
         @title_margin = TITLE_MARGIN
@@ -80,11 +100,17 @@ def initialize(figure)
         @origin = [nil, nil]
         calculate_xy_axes_origin
         @x_axis = Rubyplot::Artist::XAxis.new(self)
+        @x_dash_axis = Rubyplot::Artist::XDashAxis.new(self)
         @y_axis = Rubyplot::Artist::YAxis.new(self)
+        @y_dash_axis = Rubyplot::Artist::YDashAxis.new(self)
         @x_ticks = nil
+	@x_dash_ticks = nil
         @y_ticks = nil
+	@y_dash_ticks = nil
         @num_x_ticks = 5
+	@num_x_dash_ticks = 5
         @num_y_ticks = 4
+	@num_y_dash_ticks = 4
         @legend_box_position = :top
       end
 
@@ -113,6 +139,8 @@ def draw
         configure_title
         configure_legends
         assign_x_ticks
+	assign_x_dash_ticks
+	assign_y_dash_ticks
         assign_y_ticks
         actually_draw
       end
@@ -185,10 +213,15 @@ def height
       def x_ticks= x_ticks
         @x_ticks = x_ticks
       end
-
+      def x_dash_ticks= x_dash_ticks
+        @x_dash_ticks = x_dash_ticks
+      end
       def y_ticks= y_ticks
         @y_ticks = y_ticks
       end
+      def y_dash_ticks= y_dash_ticks
+        @y_dash_ticks = y_dash_ticks
+      end
 
       def x_title= x_title
         @x_axis.title = x_title
@@ -210,7 +243,7 @@ def assign_default_label_colors
       end
 
       def assign_x_ticks
-        @inter_x_ticks_distance = @x_axis.length / (@num_x_ticks.to_f-1)
+        @inter_x_ticks_distance = @x_axis.length / (@num_x_ticks.to_f - 1)
         unless @x_ticks
           value_distance = (@x_range[1] - @x_range[0]) / (@num_x_ticks.to_f - 1)
           @x_ticks = @num_x_ticks.times.map do |i|
@@ -232,6 +265,29 @@ def assign_x_ticks
         end
       end
 
+      def assign_x_dash_ticks
+        @inter_x_dash_ticks_distance = @x_dash_axis.length / (@num_x_dash_ticks.to_f - 1)
+        unless @x_dash_ticks
+          value_distance = (@x_dash_range[1] - @x_dash_range[0]) / (@num_x_dash_ticks.to_f - 1)
+          @x_dash_ticks = @num_x_dash_ticks.times.map do |i|
+            @x_dash_range[0] + i * value_distance
+          end
+        end
+
+        unless @x_dash_ticks.all? { |t| t.is_a?(Rubyplot::Artist::XDashTick) }
+          @x_dash_ticks.map!.with_index do |tick_label, i|
+            Rubyplot::Artist::XDashTick.new(
+              self,
+              abs_x: -i * @inter_x_dash_ticks_distance + @x_dash_axis.abs_x1,
+              abs_y: @origin[1],
+              label: Rubyplot::Utils.format_label(-tick_label),
+              length: 6,
+              label_distance: 10
+            )
+          end
+        end
+      end
+
       def assign_y_ticks
         unless @y_ticks
           val_distance = (@y_range[1] - @y_range[0]).abs / @num_y_ticks.to_f
@@ -252,6 +308,26 @@ def assign_y_ticks
         end
       end
 
+      def assign_y_dash_ticks
+        unless @y_dash_ticks
+          val_distance = (@y_dash_range[1] - @y_dash_range[0]).abs / @num_y_dash_ticks.to_f
+          @y_dash_ticks = (@y_dash_range[0]..@y_dash_range[1]).step(val_distance).map { |i| i }
+        end
+        unless @y_dash_ticks.all? { |t| t.is_a?(Rubyplot::Artist::YDashTick) }
+          inter_ticks_distance = @y_dash_axis.length / (@num_y_dash_ticks - 1)
+          @y_dash_ticks.map!.with_index do |tick_label, i|
+            Rubyplot::Artist::YDashTick.new(
+              self,
+              abs_x: @origin[0],
+              abs_y: @y_dash_axis.abs_y1 - (-i * inter_ticks_distance),
+              label: Rubyplot::Utils.format_label(-tick_label),
+              length: 6,
+              label_distance: 50
+            )
+          end
+        end
+      end
+
       def add_plot plot_type, *args, &block
         plot = with_backend plot_type, *args
         yield(plot) if block_given?
@@ -279,8 +355,8 @@ def configure_title
       end
 
       def calculate_xy_axes_origin
-        @origin[0] = abs_x + @x_axis_margin
-        @origin[1] = abs_y + height - @y_axis_margin
+        @origin[0] = abs_x + width/2
+        @origin[1] = abs_y + height/2
       end
 
       # Figure out co-ordinates of the legends
@@ -302,8 +378,12 @@ def normalize_plotting_data
       def actually_draw
         @x_axis.draw
         @x_ticks.each(&:draw)
+	@y_axis.draw
         @y_ticks.each(&:draw)
-        @y_axis.draw
+	@x_dash_axis.draw
+	@x_dash_ticks.each(&:draw)
+        @y_dash_axis.draw
+	@y_dash_ticks.each(&:draw)
         @texts.each(&:draw)
         @legend_box.draw
         @plots.each(&:draw)
@@ -327,25 +407,45 @@ def consolidate_plots
       def set_axes_ranges
         set_xrange
         set_yrange
+	set_xdashrange
+	set_ydashrange
       end
 
       def set_xrange
         if @x_range[0].nil? && @x_range[1].nil?
-          @x_range[0] = @plots.map(&:x_min).min
+          @x_range[0] = 0
           @x_range[1] = @plots.map(&:x_max).max
         end
         @x_axis.min_val = @x_range[0]
         @x_axis.max_val = @x_range[1]
       end
-
+	
+      def set_xdashrange
+        if @x_dash_range[0].nil? && @x_dash_range[1].nil?
+          @x_dash_range[0] = 0
+          @x_dash_range[1] = @plots.map(&:x_max).max
+        end
+        @x_dash_axis.min_val = @x_dash_range[1]
+        @x_dash_axis.max_val = @x_dash_range[0]
+      end
+      
       def set_yrange
         if @y_range[0].nil? && @y_range[1].nil?
-          @y_range[0] = @plots.map { |p| p.y_min }.min
+          @y_range[0] = 0
           @y_range[1] = @plots.map { |p| p.y_max }.max
         end
         @y_axis.min_val = @y_range[0]
         @y_axis.max_val = @y_range[1]
       end
+
+	def set_ydashrange
+        if @y_dash_range[0].nil? && @y_dash_range[1].nil?
+          @y_dash_range[0] = 0
+          @y_dash_range[1] = @plots.map { |p| p.y_max }.max
+        end
+        @y_dash_axis.min_val = @y_dash_range[0]
+        @y_dash_axis.max_val = @y_dash_range[1]
+      end
     end # class Axes
   end # moudle Artist
 end # module Rubyplot
diff --git a/lib/rubyplot/artist/axis.rb b/lib/rubyplot/artist/axis.rb
index 6484c5d..94773cd 100644
--- a/lib/rubyplot/artist/axis.rb
+++ b/lib/rubyplot/artist/axis.rb
@@ -1,3 +1,5 @@
 require_relative 'axis/base'
 require_relative 'axis/x_axis'
+require_relative 'axis/x_dash_axis'
 require_relative 'axis/y_axis'
+require_relative 'axis/y_dash_axis'
diff --git a/lib/rubyplot/artist/axis/x_axis.rb b/lib/rubyplot/artist/axis/x_axis.rb
index 5c35e18..eb3b98a 100644
--- a/lib/rubyplot/artist/axis/x_axis.rb
+++ b/lib/rubyplot/artist/axis/x_axis.rb
@@ -6,7 +6,7 @@ class XAxis < Axis::Base
       def initialize axes
         super
         @abs_x1 = @axes.origin[0]
-        @abs_x2 = @axes.abs_x + @axes.width - @axes.y_axis_margin
+        @abs_x2 = @axes.origin[0] + @axes.width/2 - @axes.y_axis_margin
         @major_ticks_distance = (@abs_x2 - @abs_x1) / @major_ticks_count
         @length = (@abs_x2 - @abs_x1).abs
         configure_axis_line
diff --git a/lib/rubyplot/artist/axis/x_dash_axis.rb b/lib/rubyplot/artist/axis/x_dash_axis.rb
new file mode 100644
index 0000000..fd2e3c5
--- /dev/null
+++ b/lib/rubyplot/artist/axis/x_dash_axis.rb
@@ -0,0 +1,35 @@
+require_relative 'base'
+
+module Rubyplot
+  module Artist
+    class XDashAxis < Axis::Base
+      def initialize axes
+        super
+        @abs_x1 = @axes.origin[0]
+        @abs_x2 = @axes.abs_x + @axes.y_axis_margin
+        @major_ticks_distance = (@abs_x2 - @abs_x1) / @major_ticks_count
+        @length = (@abs_x2 - @abs_x1).abs
+        configure_axis_line
+      end
+
+      private
+
+      def configure_axis_line
+        @lines << Rubyplot::Artist::Line2D.new(
+          self, abs_x1: @abs_x1, abs_y1: @axes.origin[1], abs_x2: @abs_x2, abs_y2: @axes.origin[1],
+                stroke_width: @stroke_width
+        )
+      end
+
+      def configure_title
+        @texts << Rubyplot::Artist::Text.new(
+          @title,
+          self,
+          pointsize: @axes.marker_font_size,
+          abs_y: @axes.origin[1] + 20,
+          abs_x: @axes.origin[0] + (@abs_x2 - @abs_x1)/2
+        )
+      end
+    end # class XAxis
+  end # class Artist
+end # module Rubyplot
diff --git a/lib/rubyplot/artist/axis/y_axis.rb b/lib/rubyplot/artist/axis/y_axis.rb
index ead4ab5..993e2d7 100644
--- a/lib/rubyplot/artist/axis/y_axis.rb
+++ b/lib/rubyplot/artist/axis/y_axis.rb
@@ -6,7 +6,7 @@ def initialize(*)
         @abs_x1 = @axes.origin[0]
         @abs_y1 = @axes.origin[1]
         @abs_x2 = @axes.origin[0]
-        @abs_y2 = @axes.origin[1] - (@axes.height - @axes.x_axis_margin)
+        @abs_y2 = @axes.origin[1] - (@axes.height/2 - @axes.x_axis_margin)
         @y_ticks = []
         @length = (@abs_y1 - @abs_y2).abs
         configure_axis_line
diff --git a/lib/rubyplot/artist/axis/y_dash_axis.rb b/lib/rubyplot/artist/axis/y_dash_axis.rb
new file mode 100644
index 0000000..8dfab43
--- /dev/null
+++ b/lib/rubyplot/artist/axis/y_dash_axis.rb
@@ -0,0 +1,40 @@
+module Rubyplot
+  module Artist
+    class YDashAxis < Axis::Base
+      def initialize(*)
+        super
+        @abs_x1 = @axes.origin[0]
+        @abs_y1 = @axes.origin[1]
+        @abs_x2 = @axes.origin[0]
+        @abs_y2 = @axes.origin[1] + (@axes.height/2 - @axes.x_axis_margin)
+        @y_ticks = []
+        @length = (@abs_y1 - @abs_y2).abs
+        configure_axis_line
+      end
+
+      private
+
+      def configure_axis_line
+        @lines << Rubyplot::Artist::Line2D.new(
+          self,
+          abs_x1: @abs_x1,
+          abs_y1: @abs_y1,
+          abs_x2: @abs_x2,
+          abs_y2: @abs_y2,
+          stroke_width: @stroke_width
+        )
+      end
+
+      def configure_title
+        @texts << Rubyplot::Artist::Text.new(
+          @title,
+          self,
+          rotation: -90.0,
+          abs_x: @axes.origin[0] - 10,
+          abs_y: (@abs_y1 - @abs_y2) / 2,
+          pointsize: @axes.marker_font_size
+        )
+      end
+    end # class YDashAxis
+  end # class Artist
+end # module Rubyplot
diff --git a/lib/rubyplot/artist/plot/line.rb b/lib/rubyplot/artist/plot/line.rb
index b40201d..d21578b 100644
--- a/lib/rubyplot/artist/plot/line.rb
+++ b/lib/rubyplot/artist/plot/line.rb
@@ -36,9 +36,8 @@ def draw_lines
             iy = @normalized_data[:y_values][idx_ix]
             next if ix.nil? || iy.nil?
 
-            new_x = ix * (@axes.x_axis.abs_x2 - @axes.x_axis.abs_x1).abs + @axes.abs_x +
-                    @axes.y_axis_margin
-            new_y = (@axes.y_axis.length - iy * @axes.y_axis.length) + @axes.abs_y
+            new_x = ix * (@axes.x_axis.length) + @axes.origin[0]
+            new_y = @axes.origin[1] - iy * @axes.y_axis.length
 
             unless prev_x.nil? && prev_y.nil?
               Rubyplot::Artist::Line2D.new(
diff --git a/lib/rubyplot/artist/plot/multi_bars.rb b/lib/rubyplot/artist/plot/multi_bars.rb
index 22a3ce8..b7c6a63 100644
--- a/lib/rubyplot/artist/plot/multi_bars.rb
+++ b/lib/rubyplot/artist/plot/multi_bars.rb
@@ -52,7 +52,7 @@ def configure_x_ticks
           @axes.x_ticks = labels.map.with_index do |label, i|
             Rubyplot::Artist::XTick.new(
               @axes,
-              abs_x: @axes.abs_x + @axes.y_axis_margin + i * @max_slot_width + @max_slot_width / 2,
+              abs_x: @axes.abs_x + @axes.y_axis_margin*9 + i * @max_slot_width + @max_slot_width / 2,
               abs_y: @axes.origin[1],
               label: label,
               length: 6,
@@ -64,7 +64,7 @@ def configure_x_ticks
         def set_bar_dims bar_plot, index
           bar_plot.bar_width = @max_bars_width / @bars_per_slot
           @num_max_slots.times do |i|
-            bar_plot.abs_x_left[i] = @axes.abs_x + @axes.y_axis_margin +
+            bar_plot.abs_x_left[i] = @axes.abs_x + @axes.y_axis_margin*9 +
                                      i * @max_slot_width + @padding / 2 + index * bar_plot.bar_width
             bar_plot.abs_y_left[i] = @axes.origin[1] - @axes.x_axis.stroke_width
           end
diff --git a/lib/rubyplot/artist/tick.rb b/lib/rubyplot/artist/tick.rb
index c16fea3..cefff9e 100644
--- a/lib/rubyplot/artist/tick.rb
+++ b/lib/rubyplot/artist/tick.rb
@@ -1,3 +1,5 @@
 require_relative 'tick/base'
 require_relative 'tick/x_tick'
+require_relative 'tick/x_dash_tick'
 require_relative 'tick/y_tick'
+require_relative 'tick/y_dash_tick'
diff --git a/lib/rubyplot/artist/tick/x_dash_tick.rb b/lib/rubyplot/artist/tick/x_dash_tick.rb
new file mode 100644
index 0000000..e0836e8
--- /dev/null
+++ b/lib/rubyplot/artist/tick/x_dash_tick.rb
@@ -0,0 +1,27 @@
+module Rubyplot
+  module Artist
+    class XDashTick < Tick::Base
+      def initialize(*)
+        super
+        @label = Rubyplot::Artist::Text.new(
+          @label_text.to_s,
+          @owner,
+          abs_x: @abs_x - 5,
+          abs_y: @abs_y + @length + @label_distance,
+          pointsize: @owner.marker_font_size
+        )
+      end
+
+      def draw
+        @backend.draw_line(
+          x1: @abs_x, y1: @abs_y, x2: @abs_x, y2: @abs_y + @length,
+          stroke_opacity: @tick_opacity,
+          stroke_width: @tick_width
+        )
+	if @label_text != '-0.00' 
+		@label.draw
+	end
+      end
+    end # class XDashTick
+  end # class Artist
+end # module Rubyplot
diff --git a/lib/rubyplot/artist/tick/y_dash_tick.rb b/lib/rubyplot/artist/tick/y_dash_tick.rb
new file mode 100644
index 0000000..2657f56
--- /dev/null
+++ b/lib/rubyplot/artist/tick/y_dash_tick.rb
@@ -0,0 +1,26 @@
+module Rubyplot
+  module Artist
+    class YDashTick < Tick::Base
+      def initialize(*)
+        super
+        @label = Rubyplot::Artist::Text.new(
+          @label_text.to_s,
+          @owner,
+          abs_x: @abs_x - 5 - @label_distance,
+          abs_y: @abs_y + @length,
+          pointsize: @owner.marker_font_size,
+        )
+      end
+
+      def draw
+        @backend.draw_line(
+          x1: @abs_x, y1: @abs_y, x2: @abs_x - @length, y2: @abs_y,
+          stroke_opacity: @tick_opacity,
+          stroke_width: @tick_width)
+	if @label_text !='-0.00'
+        	@label.draw
+	end
+      end
+    end # class YTick
+  end # module Artist
+end # module Rubyplot
diff --git a/lib/rubyplot/artist/tick/y_tick.rb b/lib/rubyplot/artist/tick/y_tick.rb
index c019a91..51ac5cc 100644
--- a/lib/rubyplot/artist/tick/y_tick.rb
+++ b/lib/rubyplot/artist/tick/y_tick.rb
@@ -17,7 +17,9 @@ def draw
           x1: @abs_x, y1: @abs_y, x2: @abs_x - @length, y2: @abs_y,
           stroke_opacity: @tick_opacity,
           stroke_width: @tick_width)
-        @label.draw
+	if @label_text != '0.00'
+        	@label.draw
+	end
       end
     end # class YTick
   end # module Artist
diff --git a/lib/rubyplot/backend/base.rb b/lib/rubyplot/backend/base.rb
new file mode 100644
index 0000000..e46ceb3
--- /dev/null
+++ b/lib/rubyplot/backend/base.rb
@@ -0,0 +1,10 @@
+module Rubyplot
+  module Backend
+    class Base
+      # Total height and width of the canvas in pixels.
+      attr_accessor :canvas_height, :canvas_width
+
+      attr_accessor :active_axes, :figure
+    end # class Base
+  end # module Backend
+end # module Rubyplot
diff --git a/lib/rubyplot/backend/gr_wrapper.rb b/lib/rubyplot/backend/gr_wrapper.rb
new file mode 100644
index 0000000..d1391fb
--- /dev/null
+++ b/lib/rubyplot/backend/gr_wrapper.rb
@@ -0,0 +1,94 @@
+require_relative '../../grruby.so'
+
+module Rubyplot
+  module Backend
+    # Wrapper around a GR backend. Works differently than the Image Magick wrapper
+    # since in GR there is no one-one mapping between Rubyplot artists and things
+    # that are to be drawn on the backend.
+    class GRWrapper < Base
+      def initialize
+        # Mapping between viewports and their respective Axes.
+        @axes_maps = {}
+        @file_name = nil
+        @xspread = Rubyplot::MAX_X.abs + Rubyplot::MIN_X.abs
+        @yspread = Rubyplot::MAX_Y.abs + Rubyplot::MIN_Y.abs
+      end
+
+      # Draw X axis for the currently selected Axes.
+      def draw_x_axis(minor_ticks:, origin:, major_ticks:, tick_size:)
+        @axes_maps[@active_axes] = {
+          x_minor_ticks: minor_ticks,
+          x_origin: origin,
+          x_major_ticks: major_ticks,
+          x_tick_size: tick_size
+        }
+      end
+
+      # Draw Y axis for currently selected Axes.
+      def draw_y_axis(minor_ticks:, origin:, major_ticks:, tick_size:)
+        @axes_maps[@active_axes] = {
+          y_minor_ticks: minor_ticks,
+          y_origin: origin,
+          y_major_ticks: major_ticks,
+          y_tick_size: tick_size
+        }
+      end
+
+      def draw_text
+        
+      end
+
+      def draw_line
+        
+      end
+
+      def draw
+        draw_axes
+      end
+
+      def init_output_device file_name
+        @file_name = file_name
+        Rubyplot::GR.beginprint file_name
+      end
+
+      def stop_output_device
+        Rubyplot::GR.endprint
+      end
+
+      def write file_name
+        draw
+      end
+
+      private
+
+      # Set the window on the canvas within which the plotting will take place
+      # and then call the passed block for actual plotting.
+      def within_window &block
+        vp_min_x = (@active_axes.abs_x + @active_axes.left_spacing) / @xspread
+        vp_min_y = (@active_axes.abs_y + @active_axes.bottom_spacing) / @yspread
+        vp_max_x = (@active_axes.abs_x + @active_axes.width -
+          @active_axes.right_spacing) / @xspread
+        vp_max_y = (@active_axes.abs_y + @active_axes.height -
+          @active_axes.top_spacing) / @yspread
+        
+        Rubyplot::GR.setviewport(vp_min_x, vp_max_x, vp_min_y, vp_max_y)
+        Rubyplot::GR.setwindow(
+          @active_axes.xrange[0],
+          @active_axes.xrange[1],
+          @active_axes.yrange[0],
+          @active_axes.yrange[1]
+        )
+        block.call
+      end
+
+      def draw_axes
+        @axes_maps.each do |k, v|
+          @active_axes = k
+          within_window do
+            # Call Rubyplot::GR.axes with whatever args.
+          end
+        end
+      end
+    end # class GRWrapper
+  end # module Backend
+end # module Rubyplot