Adding custom colors to the draw arg

lib/squib/api/background.rb

@@ -11,8 +11,9 @@ module Squib
     # @return [nil] nothing
     # @api public
     def background(opts = {})
-      opts = needs(opts,[:range, :color])
-      opts[:range].each { |i| @cards[i].background(opts[:color][i]) }
+      range = Args::CardRange.new(opts[:range], deck_size: size)
+      draw  = Args::Draw.new(custom_colors).load!(opts, expand_by: size, layout: layout, dpi: dpi)
+      range.each { |i| @cards[i].background(draw.color[i]) }
     end
 
   end

lib/squib/args/color_validator.rb

@@ -0,0 +1,12 @@
+module Squib
+  #@api private
+  module Args
+    module ColorValidator
+
+      def colorify(color, custom_colors = {})
+        custom_colors[color.to_s] || color.to_s
+      end
+
+    end
+  end
+end

lib/squib/args/draw.rb

@@ -1,5 +1,6 @@
 require 'cairo'
 require 'squib/args/arg_loader'
+require 'squib/args/color_validator'
 
 module Squib
   # @api private
@@ -7,9 +8,15 @@ module Squib
 
     class Draw
       include ArgLoader
+      include ColorValidator
+
+      def initialize(custom_colors = {})
+        @custom_colors = custom_colors
+      end
 
       def self.parameters
-        { fill_color: '#0000',
+        { color: :black,
+          fill_color: '#0000',
           stroke_color: :black,
           stroke_width: 2.0,
           join: :miter,
@@ -54,6 +61,18 @@ module Squib
         end
       end
 
+      def validate_fill_color(arg, _i)
+        colorify(arg, @custom_colors)
+      end
+
+      def validate_stroke_color(arg, _i)
+        colorify(arg, @custom_colors)
+      end
+
+      def validate_color(arg, _i)
+        colorify(arg, @custom_colors)
+      end
+
     end
 
   end