=begin

= File
	graphics/state.rb

= Info
	This file is part of Origami, PDF manipulation framework for Ruby
	Copyright (C) 2010	Guillaume Delugré <guillaume AT security-labs DOT org>
	All right reserved.
	
  Origami is free software: you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Origami is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with Origami.  If not, see <http://www.gnu.org/licenses/>.

=end

require 'matrix'

module Origami

  module Graphics

    class GraphicsStateError < Exception #:nodoc:
    end

    class State

      #
      # Device-independent parameters.
      #
      attr_accessor :ctm
      attr_accessor :clipping_path
      attr_accessor :stroking_colorspace, :nonstroking_colorspace, :stroking_color, :nonstroking_color
      attr_accessor :text_state
      attr_accessor :line_width, :line_cap, :line_join, :miter_limit, :dash_pattern
      attr_accessor :rendering_intent
      attr_accessor :stroke_adjustment
      attr_accessor :blend_mode, :soft_mask, :alpha_constant, :alpha_source

      attr_reader :current_path

      def initialize
        
        @stack = []
        @current_path = []
        @text_state = Text::State.new

        self.reset
      end

      def reset

        @ctm = Matrix.identity(3)
        @clipping_path = nil
        @stroking_colorspace = @nonstroking_colorspace = Color::Space::DEVICE_GRAY
        @stroking_color = @nonstroking_color = [ 0.0 ] #black
        @text_state.reset
        @line_width = 1.0
        @line_cap = LineCapStyle::BUTT_CAP
        @line_join = LineJoinStyle::MITER_JOIN
        @miter_limit = 10.0
        @dash_pattern = DashPattern.new([], 0)
        @rendering_intent = Color::Intent::RELATIVE
        @stroke_adjustment = false
        @blend_mode = Color::BlendMode::NORMAL
        @soft_mask = :None
        @alpha_constant = 1.0
        @alpha_source = false

      end

      def save  
        context = 
        [
          @ctm, @clipping_path,
          @stroking_colorspace, @nonstroking_colorspace,
          @stroking_color, @nonstroking_color,
          @text_state, @line_width, @line_cap, @line_join,
          @miter_limit, @dash_pattern, @rendering_intent,
          @stroke_adjustment,
          @blend_mode, @soft_mask, @alpha_constant, @alpha_source
        ]
        @stack.push(context)
      end

      def restore
        raise GraphicsStateError, "Cannot restore context : empty stack" if @stack.empty?

        @ctm, @clipping_path,
        @stroking_colorspace, @nonstroking_colorspace,
        @stroking_color, @nonstroking_color,
        @text_state, @line_width, @line_cap, @line_join,
        @miter_limit, @dash_pattern, @rendering_intent,
        @stroke_adjustment,
        @blend_mode, @soft_mask, @alpha_constant, @alpha_source = @stack.pop
      end

    end

    #
    # Generic Graphic state
    # 4.3.4 Graphics State Parameter Dictionaries p219
    #
    class ExtGState < Dictionary
      
      include StandardObject

      field   :Type,          :Type => Name, :Default => :ExtGState, :Required => true
      field   :LW,            :Type => Integer, :Version => "1.3"
      field   :LC,            :Type => Integer, :Version => "1.3"
      field   :LJ,            :Type => Integer, :Version => "1.3"
      field   :ML,            :Type => Number, :Version => "1.3"
      field   :D,             :Type => Array, :Version => "1.3"
      field   :RI,            :Type => Name, :Version => "1.3"
      field   :OP,            :Type => Boolean
      field   :op,            :Type => Boolean, :Version => "1.3"
      field   :OPM,           :Type => Number, :Version => "1.3"
      field   :Font,          :Type => Array, :Version => "1.3"
      field   :BG,            :Type => Object
      field   :BG2,           :Type => Object, :Version => "1.3"
      field   :UCR,           :Type => Object
      field   :UCR2,          :Type => Object, :Version => "1.3"
      field   :TR,            :Type => Object
      field   :TR2,           :Type => Object, :Version => "1.3" 
      field   :HT,            :Type => [ Dictionary, Name, Stream ]
      field   :FL,            :Type => Number, :Version => "1.3"
      field   :SM,            :Type => Number, :Version => "1.3"
      field   :SA,            :Type => Boolean
      field   :BM,            :Type => [ Name, Array ], :Version => "1.4"
      field   :SMask,         :Type => [ Dictionary, Array ], :Version => "1.4"
      field   :CA,            :Type => Number
      field   :ca,            :Type => Number, :Version => "1.4"
      field   :AIS,           :Type => Boolean, :Version => "1.4"
      field   :TK,            :Type => Boolean, :Version => "1.4"

    end # class ExtGState

  end #module Graphics 
 
  class PDF::Instruction
    insn  'q' do |canvas| canvas.gs.save; canvas.gs.reset end
    insn  'Q' do |canvas| canvas.gs.restore end
    insn  'w', Real do |canvas, lw| canvas.gs.line_width = lw end
    insn  'J', Real do |canvas, lc| canvas.gs.line_cap = lc end
    insn  'j', Real do |canvas, lj| canvas.gs.line_join = lj end
    insn  'M', Real do |canvas, ml| canvas.gs.miter_limit = ml end
    
    insn  'd', Array, Integer do |canvas, array, phase| 
      canvas.gs.dash_pattern = Graphics::DashPattern.new array, phase
    end

    insn  'ri', Name do |canvas, ri| canvas.gs.rendering_intent = ri end
  end
end