Module: Prawn::SVG::TransformParser

Includes:
PDFMatrix
Included in:
Elements::Base
Defined in:
lib/prawn/svg/transform_parser.rb

Instance Method Summary collapse

Methods included from PDFMatrix

#load_matrix, #matrix_for_pdf, #rotation_matrix, #scale_matrix, #translation_matrix

Instance Method Details

#parse_transform_attribute(transform, space: :pdf) ⇒ Object 



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# File 'lib/prawn/svg/transform_parser.rb', line 4

def parse_transform_attribute(transform, space: :pdf)
  matrix = Matrix.identity(3)

  flip = space == :svg ? 1.0 : -1.0

  parse_css_method_calls(transform).each do |name, arguments|
    case name
    when 'translate'
      x, y = arguments
      matrix *= translation_matrix(x_pixels(x.to_f), flip * y_pixels(y.to_f))

    when 'translateX'
      x = arguments.first
      matrix *= translation_matrix(x_pixels(x.to_f), 0.0)

    when 'translateY'
      y = arguments.first
      matrix *= translation_matrix(0.0, flip * y_pixels(y.to_f))

    when 'rotate'
      angle, x, y = arguments.collect(&:to_f)
      angle = angle * Math::PI / 180.0

      rotation = rotation_matrix(angle, space: space)

      case arguments.length
      when 1
        matrix *= rotation
      when 3
        matrix *= translation_matrix(x_pixels(x.to_f), flip * y_pixels(y.to_f))
        matrix *= rotation
        matrix *= translation_matrix(-x_pixels(x.to_f), -flip * y_pixels(y.to_f))
      else
        warnings << "transform 'rotate' must have either one or three arguments"
      end

    when 'scale'
      x_scale = arguments[0].to_f
      y_scale = (arguments[1] || x_scale).to_f
      matrix *= scale_matrix(x_scale, y_scale)

    when 'skewX'
      angle = arguments[0].to_f * Math::PI / 180.0
      matrix *= Matrix[[1, flip * Math.tan(angle), 0], [0, 1, 0], [0, 0, 1]]

    when 'skewY'
      angle = arguments[0].to_f * Math::PI / 180.0
      matrix *= Matrix[[1, 0, 0], [flip * Math.tan(angle), 1, 0], [0, 0, 1]]

    when 'matrix'
      if arguments.length == 6
        a, b, c, d, e, f = arguments.collect(&:to_f)
        matrix *= Matrix[[a, flip * c, e], [flip * b, d, flip * f], [0, 0, 1]]
      else
        warnings << "transform 'matrix' must have six arguments"
      end

    else
      warnings << "Unknown/unsupported transformation '#{name}'; ignoring"
    end
  end

  matrix
end