embellishable.rb

#--
# $Id: embellishable.rb,v 1.8 2008/02/24 18:26:36 rmagick Exp $
# Copyright (C) 2008 Timothy P. Hunter
#++

module Magick
    class RVG

        # Parent class of Circle, Ellipse, Text, etc.
        class Shape             #:nodoc:
            include Stylable
            include Transformable
            include Duplicatable

            # Each shape can have its own set of transforms and styles.
            def add_primitives(gc)
                gc.push
                add_transform_primitives(gc)
                add_style_primitives(gc)
                gc.__send__(@primitive, *@args)
                gc.pop
            end

        end     # class Shape

        class Circle < Shape

            # Define a circle with radius +r+ and centered at [<tt>cx</tt>, <tt>cy</tt>].
            # Use the RVG::ShapeConstructors#circle method to create Circle objects in a container.
            def initialize(r, cx=0, cy=0)
                super()
                r, cx, cy = Magick::RVG.convert_to_float(r, cx, cy)
                if r < 0
                    raise ArgumentError, "radius must be >= 0 (#{r} given)"
                end
                @primitive = :circle
                @args = [cx, cy, cx+r, cy]
                self
            end

        end     # class Circle

        class Ellipse < Shape

            # Define an ellipse with a center at [<tt>cx</tt>, <tt>cy</tt>], a horizontal radius +rx+
            # and a vertical radius +ry+.
            # Use the RVG::ShapeConstructors#ellipse method to create Ellipse objects in a container.
            def initialize(rx, ry, cx=0, cy=0)
                super()
                rx, ry, cx, cy = Magick::RVG.convert_to_float(rx, ry, cx, cy)
                if rx < 0 || ry < 0
                    raise ArgumentError, "radii must be >= 0 (#{rx}, #{ry} given)"
                end
                @primitive = :ellipse
                # Ellipses are always complete.
                @args = [cx, cy, rx, ry, 0, 360]
            end

        end     # class Ellipse

        class Line < Shape

            # Define a line from [<tt>x1</tt>, <tt>y1</tt>] to [<tt>x2</tt>, <tt>y2</tt>].
            # Use the RVG::ShapeConstructors#line method to create Line objects in a container.
            def initialize(x1=0, y1=0, x2=0, y2=0)
                super()
                @primitive = :line
                @args = [x1, y1, x2, y2]
            end

        end     # class Line

        class Path < Shape

            # Define an SVG path. The argument can be either a path string
            # or a PathData object.
            # Use the RVG::ShapeConstructors#path method to create Path objects in a container.
            def initialize(path)
                super()
                @primitive = :path
                @args = [path.to_s]
            end

        end     # class Path

        class Rect < Shape

            # Define a width x height rectangle. The upper-left corner is at [<tt>x</tt>, <tt>y</tt>].
            # If either <tt>width</tt> or <tt>height</tt> is 0, the rectangle is not rendered.
            # Use the RVG::ShapeConstructors#rect method to create Rect objects in a container.
            def initialize(width, height, x=0, y=0)
                super()
                width, height, x, y = Magick::RVG.convert_to_float(width, height, x, y)
                if width < 0 || height < 0
                    raise ArgumentError, "width, height must be >= 0 (#{width}, #{height} given)"
                end
                @args = [x, y, x+width, y+height]
                @primitive = :rectangle
            end

            # Specify optional rounded corners for a rectangle. The arguments
            # are the x- and y-axis radii. If y is omitted it defaults to x.
            def round(rx, ry=nil)
                rx, ry = Magick::RVG.convert_to_float(rx, ry || rx)
                if rx < 0 || ry < 0
                    raise ArgumentError, "rx, ry must be >= 0 (#{rx}, #{ry} given)"
                end
                @args << rx << ry
                @primitive = :roundrectangle
                self
            end

        end     # class Rect

        class PolyShape < Shape

            def polypoints(points)
                case points.length
                    when 1
                        points = Array(points[0])
                    when 2
                        x_coords = Array(points[0])
                        y_coords = Array(points[1])
                        unless x_coords.length > 0 && y_coords.length > 0
                            raise ArgumentError, "array arguments must contain at least one point"
                        end
                        n = x_coords.length - y_coords.length
                        short = n > 0 ? y_coords : x_coords
                        olen = short.length
                        n.abs.times {|x| short << short[x % olen]}
                        points = x_coords.zip(y_coords).flatten
                end
                n = points.length
                if n < 4 || n % 2 != 0
                    raise ArgumentError, "insufficient/odd number of points specified: #{n}"
                end
                return Magick::RVG.convert_to_float(*points)
            end

        end     # class PolyShape

        class Polygon < PolyShape

            # Draws a polygon. The arguments are [<tt>x</tt>, <tt>y</tt>] pairs that
            # define the points that make up the polygon. At least two
            # points must be specified. If the last point is not the
            # same as the first, adds an additional point to close
            # the polygon.
            # Use the RVG::ShapeConstructors#polygon method to create Polygon objects in a container.
            def initialize(*points)
                super()
                @primitive = :polygon
                @args = polypoints(points)
            end

        end     # class Polygon

        class Polyline < PolyShape

            # Draws a polyline. The arguments are [<tt>x</tt>, <tt>y</tt>] pairs that
            # define the points that make up the polyline. At least two
            # points must be specified.
            # Use the RVG::ShapeConstructors#polyline method to create Polyline objects in a container.
            def initialize(*points)
                super()
                points = polypoints(points)
                @primitive = :polyline
                @args = Magick::RVG.convert_to_float(*points)
            end

        end     # class Polyline


        class Image
            include Stylable
            include Transformable
            include Describable
            include PreserveAspectRatio
            include Duplicatable

          private
            def align_to_viewport(scale)
                tx = case @align
                        when 'none', /\AxMin/
                            0
                        when NilClass, /\AxMid/
                            (@width - @image.columns*scale) / 2.0
                        when /\AxMax/
                            @width - @image.columns*scale
                end

                ty = case @align
                        when 'none', /YMin\z/
                            0
                        when NilClass, /YMid\z/
                            (@height - @image.rows*scale) / 2.0
                        when /YMax\z/
                            @height - @image.rows*scale
                end
                return [tx, ty]
            end

            def add_composite_primitive(gc)
                if @align == 'none'
                    # Let RMagick do the scaling
                    scale = 1.0
                    width, height = @width, @height
                elsif @meet_or_slice == 'meet'
                    scale = [@width/@image.columns, @height/@image.rows].min
                    width, height = @image.columns, @image.rows
                else
                    # Establish clipping path around the current viewport
                    name = __id__.to_s
                    gc.define_clip_path(name) do
                        gc.path("M#{@x},#{@y} l#{@width},0 l0,#{@height} l-#{@width},0 l0,-#{@height}z")
                    end

                    gc.clip_path(name)
                    scale = [@width/@image.columns, @height/@image.rows].max
                    width, height = @image.columns, @image.rows
                end
                tx, ty = align_to_viewport(scale)
                gc.composite(@x+tx, @y+ty, width*scale, height*scale, @image)
            end

            def init_viewbox()
                @align = nil
                @vbx_width, @vbx_height = @image.columns, @image.rows
                @meet_or_slice = 'meet'
            end

          public

            # Composite a raster image in the viewport defined by [x,y] and
            # +width+ and +height+.
            # Use the RVG::ImageConstructors#image method to create Text objects in a container.
            def initialize(image, width=nil, height=nil, x=0, y=0)
                super()             # run module initializers
                @image = image.copy # use a copy of the image in case app. re-uses the argument
                @x, @y, @width, @height = Magick::RVG.convert_to_float(x, y, width || @image.columns, height || @image.rows)
                if @width < 0 || @height < 0
                    raise ArgumentError, "width, height must be >= 0"
                end
                init_viewbox()
            end

            def add_primitives(gc)      #:nodoc:
                # Do not render if width or height is 0
                return if @width == 0 || @height == 0
                gc.push
                add_transform_primitives(gc)
                add_style_primitives(gc)
                add_composite_primitive(gc)
                gc.pop
            end

        end     # class Image


        # Methods that construct basic shapes within a container
        module ShapeConstructors

            # Draws a circle whose center is [<tt>cx</tt>, <tt>cy</tt>] and radius is +r+.
            def circle(r, cx=0, cy=0)
                circle = Circle.new(r, cx, cy)
                @content << circle
                return circle
            end

            # Draws an ellipse whose center is [<tt>cx</tt>, <tt>cy</tt>] and having
            # a horizontal radius +rx+ and vertical radius +ry+.
            def ellipse(rx, ry, cx=0, cy=0)
                ellipse = Ellipse.new(rx, ry, cx, cy)
                @content << ellipse
                return ellipse
            end

            # Draws a line from [<tt>x1</tt>, <tt>y1</tt>] to  [<tt>x2</tt>, <tt>y2</tt>].
            def line(x1=0, y1=0, x2=0, y2=0)
                line = Line.new(x1, y1, x2, y2)
                @content << line
                return line
            end

            # Draws a path defined by an SVG path string or a PathData
            # object.
            def path(path)
                path = Path.new(path)
                @content << path
                return path
            end

            # Draws a rectangle whose upper-left corner is [<tt>x</tt>, <tt>y</tt>] and
            # with the specified +width+ and +height+. Unless otherwise
            # specified the rectangle has square corners. Returns a
            # Rectangle object.
            #
            # Draw a rectangle with rounded corners by calling the #round
            # method on the Rectangle object. <tt>rx</tt> and <tt>ry</tt> are
            # the corner radii in the x- and y-directions. For example:
            #   canvas.rect(width, height, x, y).round(8, 6)
            # If <tt>ry</tt> is omitted it defaults to <tt>rx</tt>.
            def rect(width, height, x=0, y=0)
                rect = Rect.new(width, height, x, y)
                @content << rect
                return rect
            end

            # Draws a polygon. The arguments are [<tt>x</tt>, <tt>y</tt>] pairs that
            # define the points that make up the polygon. At least two
            # points must be specified. If the last point is not the
            # same as the first, adds an additional point to close
            # the polygon.
            def polygon(*points)
                polygon = Polygon.new(*points)
                @content << polygon
                return polygon
            end

            # Draws a polyline. The arguments are [<tt>x</tt>, <tt>y</tt>] pairs that
            # define the points that make up the polyline. At least two
            # points must be specified.
            def polyline(*points)
                polyline = Polyline.new(*points)
                @content << polyline
                return polyline
            end

        end     # module ShapeContent

        # Methods that reference ("use") other drawable objects within a container
        module UseConstructors

            # Reference an object to be inserted into the container's
            # content. [<tt>x</tt>,<tt>y</tt>] is the offset from the upper-left
            # corner. If the argument is an RVG or Image object and +width+ and +height+
            # are specified, these values will override the +width+ and +height+
            # attributes on the argument.
            def use(obj, x=0, y=0, width=nil, height=nil)
                use = Use.new(obj, x, y, width, height)
                @content << use
                return use
            end

        end     # module UseConstructors

        # Methods that construct container objects within a container
        module StructureConstructors

            # Establishes a new viewport. [<tt>x</tt>, <tt>y</tt>] is the coordinate of the
            # upper-left corner within the containing viewport. This is a
            # _container_ method. Styles and
            # transforms specified on this object will be used by objects
            # contained within, unless overridden by an inner container or
            # the contained object itself.
            def rvg(cols, rows, x=0, y=0, &block)
                rvg = Magick::RVG.new(cols, rows, &block)
                begin
                    x, y = Float(x), Float(y)
                rescue ArgumentError
                    args = [cols, rows, x, y]
                    raise ArgumentError, "at least one argument is not convertable to Float (got #{args.collect {|a| a.class}.join(', ')})"
                end
                rvg.corner(x, y)
                @content << rvg
                return rvg
            end

            # Defines a group.
            #
            # This method constructs a new
            # Group _container_ object. The styles and
            # transforms specified on this object will be used by objects
            # contained within, unless overridden by an inner container or
            # the contained object itself.
            # Define grouped elements by calling RVG::Embellishable
            # methods within the associated block.
            def g(&block)
                group = Group.new(&block)
                @content << group
                return group
            end

        end     # module StructureConstructors

        # Methods that construct raster image objects within a container
        module ImageConstructors

            # Composite a raster image at [<tt>x</tt>,<tt>y</tt>]
            # in a viewport of the specified <tt>width</tt> and <tt>height</tt>.
            # If not specified, the width and height are the width and height
            # of the image. Use the RVG::PreserveAspectRatio#preserve_aspect_ratio method to
            # control the placement and scaling of the image within the
            # viewport. By default, the image is scaled to fit inside the
            # viewport and centered within the viewport.
            def image(image, width=nil, height=nil, x=0, y=0)
                img = Image.new(image, width, height, x, y)
                @content << img
                return img
            end

        end     # module ImageConstructors

        # Methods that create shapes, text, and other drawable objects
        # within container objects such as ::Magick::RVG and
        # ::Magick::RVG::Group
        module Embellishable
            include StructureConstructors
            include ShapeConstructors
            include TextConstructors
            include UseConstructors
            include ImageConstructors
        end     # module Embellishable

    end # class RVG
end # module Magick