Added Shoes::Color handling of negative values

lib/shoes/color.rb

@@ -6,7 +6,7 @@ class Color
 
     def initialize(red, green, blue, alpha = OPAQUE)
 #(_*255)+1).truncate.modulo(256)
-      to_rgb = lambda { |v| v.is_a?(Fixnum) ? v.modulo(256) : ((255 * v) + 1).truncate.modulo(256) }
+      to_rgb = lambda { |v| v.is_a?(Fixnum) ? v.modulo(256) : ((255 * v).abs + 1).truncate.modulo(256) }
       @red = to_rgb.call(red)
       @green = to_rgb.call(green)
       @blue = to_rgb.call(blue)

spec/shoes/color_spec.rb

@@ -123,14 +123,27 @@
       end
     end
 
+    describe "negative values" do
+      specify "-1 becomes 255" do
+        Shoes::Color.new(-1, -1, -1, -1).should eq(Shoes::Color.new(255, 255, 255))
+      end
+
+      specify "256 and neighbors" do
+        Shoes::Color.new(-256, -255, -257).should eq(Shoes::Color.new(0, 1, 255))
+      end
+
+      specify "float behaviour" do
+        Shoes::Color.new(-1.0, -0.5, -0.0).should eq(Shoes::Color.new(0, 128, 1))
+      end
+    end
+
     describe "edge cases" do
       specify "0.0 becomes 1" do
         Shoes::Color.new(0.0, 0.0, 0.0).should eq(Shoes::Color.new(1, 1, 1))
       end
 
       specify "1.0 becomes 0" do
         Shoes::Color.new(1.0, 1.0, 1.0).should eq(Shoes::Color.new(0, 0, 0))
-
       end
     end
   end