require 'rvg/rvg'

rvg = Magick::RVG.new(450, 300) do |canvas|
  canvas.desc = 'Example Preserve Aspect Ratio'
  canvas.background_fill = 'white'

  canvas.rect(448, 298, 1, 1).styles(:fill=>'none', :stroke=>'blue')

  # Define the smiley-face
  smile = Magick::RVG::Group.new do |grp|
    grp.translate(0, 5)
    grp.circle(10, 15, 15).styles(:fill=>'yellow', :stroke=>'none')
    grp.circle(1.5, 12, 12).styles(:fill=>'black', :stroke=>'none')
    grp.circle(1.5, 17, 12).styles(:fill=>'black', :stroke=>'none')
    grp.path('M10 19 A 8 8 0 0 0 20 19').styles(:stroke=>'black', :stroke_width=>2)
  end

  viewport1 = Magick::RVG::Group.new do |grp|
    grp.rect(49, 29, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
  end

  viewport2 = Magick::RVG::Group.new do |grp|
    grp.rect(29, 39, 0.5, 0.5).styles(:fill=>'black', :stroke=>'red')
  end

  # SVG to fit
  grp = canvas.g.styles(:font_size=>9) do |grp|
    grp.text(10, 30, 'SVG to fit')
    grp.g.translate(20, 40) do |grp2|
      grp2.use(viewport2)
      grp2.use(smile)
    end

    # Viewport 1
    grp.g.translate(10, 120) do |grp2|
      grp2.use(viewport1)
    end
    grp.text(10, 110, 'Viewport 1')

    # Viewport 2
    grp.g.translate(20, 190) do |grp2|
      grp2.rect(29, 50, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
    end
    grp.text(10, 180, 'Viewport 2')

    # meet-group-1
    grp.g.translate(100, 60) do |grp2|
      grp2.text(0, -30, '--------------- meet ---------------')
      grp2.g do |grp3|
        grp3.text(0, -10, 'xMin*')
        grp3.use(viewport1)

        # xMin
        grp3.rvg(50, 30).viewbox(0,0,30,40).preserve_aspect_ratio('xMinYMin', 'meet') do |canvas2|
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end

      # xMid
      grp2.g.translate(70, 0) do |grp3|
        grp3.text(0, -10, 'xMid*')
        grp3.use(viewport1)
        grp3.rvg(50, 30).viewbox(0, 0, 30, 40).preserve_aspect_ratio('xMidYMid', 'meet') do |canvas2|
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end

      # xMax
      grp2.g.translate(0, 70) do |grp3|
        grp3.text(0, -10, 'xMax*')
        grp3.use(viewport1)
        grp3.rvg(50, 30).viewbox(0,0,30,40).preserve_aspect_ratio('xMaxYMax', 'meet') do |canvas2|
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end
    end

    # meet-group-2
    grp.g.translate(250, 60) do |grp2|
      grp2.text(0, -30, '--------------- meet ---------------')

      # xMin
      grp2.g do |grp3|
        grp3.text(0, -10, '*YMin')
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60).viewbox(0,0,30,40).preserve_aspect_ratio('xMinYMin', 'meet') do |canvas2|
          canvas2.use(viewport2)
          canvas2.use(smile)
        end
      end

      # xMid
      grp2.g.translate(50, 0) do |grp3|
        grp3.text(0, -10, '*YMid')
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60).viewbox(0, 0, 30, 40).preserve_aspect_ratio('xMidYMid', 'meet') do |canvas2|
          canvas2.use(viewport2)
          canvas2.use(smile)
        end
      end

      # xMax
      grp2.g.translate(100, 0) do |grp3|
        grp3.text(0, -10, '*YMax')
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60).viewbox(0,0,30,40).preserve_aspect_ratio('xMaxYMax', 'meet') do |canvas2|
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end
    end

    # slice-group-1
    grp.g.translate(100, 220) do |grp2|
      grp2.text(0, -30, '--------------- slice ---------------')

      # xMin
      grp2.g do |grp3|
        grp3.text(0, -10, 'xMin*')
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60) do |canvas2|
          canvas2.preserve_aspect_ratio('xMinYMin', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.use(viewport2)
          canvas2.use(smile)
        end
      end

      # xMid
      grp2.g do |grp3|
        grp3.text(0, -10, 'xMid*')
        grp3.translate(50, 0)
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60) do |canvas2|
          canvas2.preserve_aspect_ratio('xMidYMid', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end

      # xMax
      grp2.g do |grp3|
        grp3.text(0, -10, 'xMax*')
        grp3.translate(100, 0)
        grp3.rect(29, 59, 0.5, 0.5).styles(:fill => 'none', :stroke => 'blue')
        grp3.rvg(30, 60) do |canvas2|
          canvas2.preserve_aspect_ratio('xMaxYMax', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end
    end

    # slice-group-2
    grp.g.translate(250, 200) do |grp2|
      grp2.text(0, -30, '--------------- slice ---------------')

      # YMin
      grp2.g do |grp3|
        grp3.text(0, -10, '*YMin')
        grp3.use(viewport1)
        grp3.rvg(50, 30) do |canvas2|
          canvas2.preserve_aspect_ratio('xMinYMin', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end

      # YMid
      grp2.g do |grp3|
        grp3.text(0, -10, '*YMid')
        grp3.translate(70, 0)
        grp3.use(viewport1)
        grp3.rvg(50, 30) do |canvas2|
          canvas2.preserve_aspect_ratio('xMidYMid', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end

      # YMax
      grp2.g do |grp3|
        grp3.text(0, -10, '*YMax')
        grp3.translate(140, 0)
        grp3.use(viewport1)
        grp3.rvg(50, 30) do |canvas2|
          canvas2.preserve_aspect_ratio('xMaxYMax', 'slice')
          canvas2.viewbox(0,0,30,40)
          canvas2.rect(29, 39, 0.5, 0.5).styles(:fill => 'black', :stroke => 'red')
          canvas2.use(smile)
        end
      end
    end
  end
end

rvg.draw.write('PreserveAspectRatio.gif')