#--
# $Id: pathdata.rb,v 1.5 2009/02/28 23:52:28 rmagick Exp $
# Copyright (C) 2009 Timothy P. Hunter
#++
module Magick
  class RVG
    # The PathData class provides an object-oriented way to produce an SVG
    # path. Each of the methods corresponds to a path command. Construct a
    # path by calling one or more methods. The path object can be passed
    # as an argument to the RVG::ShapeConstructors#path method.
    class PathData
      private

      def add_points(req, *coords)
        if coords
          if coords.length % req != 0
            fail ArgumentError, "wrong number of coordinates specified. A multiple of #{req} required, #{req+coords.length} given."
          end
          coords.each {|c| @path << ('%g' % c)}
        end
      end

      public

      # Construct an empty path
      def initialize
        @path = ''
      end

      # Convert the path to its string equivalent.
      def to_s
        @path
      end

      def deep_copy(h = nil)  #:nodoc:
        @path.dup
      end

      # Add a <tt>moveto</tt> command. If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def moveto(abs, x, y, *coords)
        @path << sprintf('%s%g,%g ', (abs ? 'M' : 'm'), x, y)
        # "subsequent pairs are treated as implicit lineto commands"
        add_points(2, *coords)
      end

      # Add a <tt>closepath</tt> command. The <tt>abs</tt> argument
      # is ignored.
      def closepath(abs = true)
        @path << 'Z' # ignore `abs'
      end

      # Add a <tt>lineto</tt> command. Any number of x,y coordinate
      # pairs may be specified. If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def lineto(abs, x, y, *coords)
        @path << sprintf('%s%g,%g ', (abs ? 'L' : 'l'), x, y)
        # "a number of coordinate pairs may be specified to draw a polyline"
        add_points(2, *coords)
      end

      # Add a <tt>horizontal lineto</tt> command. If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def hlineto(abs, x)
        @path << sprintf('%s%g ', (abs ? 'H' : 'h'), x)
      end

      # Add a <tt>vertical lineto</tt> command. If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def vlineto(abs, y)
        @path << sprintf('%s%g ', (abs ? 'V' : 'v'), y)
      end

      # Add a <tt>curveto</tt> (<em>cubic Bezier</em>) command.
      # If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def curveto(abs, x1, y1, x2, y2, x, y, *coords)
        @path << sprintf('%s%g,%g %g,%g %g,%g ', (abs ? 'C' : 'c'), x1, y1, x2, y2, x, y)
        # "multiple sets of coordinates may be specified to draw a polybezier"
        add_points(6, *coords)
      end

      # Add a <tt>smooth curveto</tt> (<em>cubic Bezier</em>) command.
      # If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def smooth_curveto(abs, x2, y2, x, y, *coords)
        @path << sprintf('%s%g,%g %g,%g ', (abs ? 'S' : 's'), x2, y2, x, y)
        # "multiple sets of coordinates may be specified to draw a polybezier"
        add_points(4, *coords)
      end

      # Add a <tt>quadratic Bezier curveto</tt> command.
      # If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def quadratic_curveto(abs, x1, y1, x, y, *coords)
        @path << sprintf('%s%g,%g %g,%g ', (abs ? 'Q' : 'q'), x1, y1, x, y)
        add_points(4, *coords)
      end

      # Add a <tt>smooth quadratic Bezier curveto</tt> command.
      # If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.
      def smooth_quadratic_curveto(abs, x, y, *coords)
        @path << sprintf('%s%g,%g ', (abs ? 'T' : 't'), x, y)
        add_points(2, *coords)
      end

      # Add an <tt>arc</tt> command.
      # If <tt>abs</tt> is
      # <tt>true</tt> the coordinates are absolute, otherwise
      # the coordinates are relative.

      def arc(abs, rx, ry, x_axis_rotation, large_arc_flag, sweep_flag, x, y)
        @path << sprintf('%s%g,%g %g %d %d %g,%g ', (abs ? 'A' : 'a'), rx, ry, x_axis_rotation, large_arc_flag, sweep_flag, x, y)
      end
    end # class PathData
  end # class RVG
end # module Magick
