#--
# $Id: pathdata.rb,v 1.2 2005/12/31 14:41:04 rmagick Exp $
# Copyright (C) 2006 Timothy P. Hunter
#++

class Magick::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
                    raise 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 Magick::RVG

