Clone the GraphicsState object more thoroughly

lib/pdf/core/graphics_state.rb

@@ -43,17 +43,23 @@ def empty?
 
     end
 
+    # NOTE: This class may be a good candidate for a copy-on-write hash.
     class GraphicState
-      attr_accessor :color_space, :dash, :cap_style, :join_style, :line_width, :fill_color, :stroke_color
+      attr_accessor :color_space, :dash, :cap_style, :join_style, :line_width, 
+                    :fill_color, :stroke_color
 
       def initialize(previous_state = nil)
-        @color_space = previous_state ? previous_state.color_space.dup : {}
-        @fill_color = previous_state ? previous_state.fill_color : "000000"
-        @stroke_color = previous_state ? previous_state.stroke_color : "000000"
-        @dash = previous_state ? previous_state.dash.dup : { :dash => nil, :space => nil, :phase => 0 }
-        @cap_style = previous_state ? previous_state.cap_style : :butt
-        @join_style = previous_state ? previous_state.join_style : :miter
-        @line_width = previous_state ? previous_state.line_width : 1
+        if previous_state
+          initialize_copy(previous_state)
+        else
+          @color_space  = {}
+          @fill_color   = "000000"
+          @stroke_color = "000000"
+          @dash         = { :dash => nil, :space => nil, :phase => 0 }
+          @cap_style    = :butt
+          @join_style   = :miter
+          @line_width   = 1
+        end
       end
 
       def dash_setting
@@ -67,8 +73,16 @@ def dash_setting
       private
 
       def initialize_copy(other)
-        @color_space = other.color_space.dup
-        @dash = other.dash.dup
+        # mutable state
+        @color_space  = other.color_space.dup
+        @fill_color   = other.fill_color.dup
+        @stroke_color = other.stroke_color.dup
+        @dash         = other.dash.dup
+
+        # immutable state that doesn't need to be duped
+        @cap_style    = other.cap_style
+        @join_style   = other.join_style
+        @line_width   = other.line_width
       end
     end
   end

spec/graphics_spec.rb

@@ -479,16 +479,22 @@
     }.should raise_error(PDF::Core::Errors::EmptyGraphicStateStack)
   end
 
-  it "should dup the color_space and dash hashes when passing in a previous_state to the initializer" do
+  it "should copy mutable attributes when passing a previous_state to the initializer" do
     new_state = PDF::Core::GraphicState.new(@pdf.graphic_state)
-    new_state.color_space.object_id.should_not == @pdf.graphic_state.color_space.object_id
-    new_state.dash.object_id.should_not == @pdf.graphic_state.dash.object_id
+
+    [:color_space, :dash, :fill_color, :stroke_color].each do |attr|
+      new_state.send(attr).should == @pdf.graphic_state.send(attr)
+      new_state.send(attr).should_not equal(@pdf.graphic_state.send(attr))
+    end
   end
 
   it "should dup the color_space and dash hashes when duping" do
     new_state = @pdf.graphic_state.dup
-    new_state.color_space.object_id.should_not == @pdf.graphic_state.color_space.object_id
-    new_state.dash.object_id.should_not == @pdf.graphic_state.dash.object_id
+
+    [:color_space, :dash, :fill_color, :stroke_color].each do |attr|
+      new_state.send(attr).should == @pdf.graphic_state.send(attr)
+      new_state.send(attr).should_not equal(@pdf.graphic_state.send(attr))
+    end
   end
 end