Module: NSWTopo::Declination

Includes:

Vector

Defined in:

lib/nswtopo/layer/declination.rb

Constant Summary

CREATE =

%w[angle spacing arrows offset]

DEFAULTS =

YAML.load "spacing: 40.0\noffset: 0.0\narrows: 160.0\nstroke: darkred\nstroke-width: 0.1\nsymbol:\n  path:\n    d: M 0 0 L 0.4 2 L 0 1.3 L -0.4 2 Z\n    stroke: none\n"

Constants included from Vector

Vector::FONT_SCALED_ATTRIBUTES, Vector::MARGIN, Vector::SVG_ATTRIBUTES

Instance Method Summary

• #get_features ⇒ Object
• #to_s ⇒ Object

Methods included from Vector

#categorise, #create, #drawing_features, #features, #filename, #labeling_features, #params_for, #render, #svg_path_data, #to_mm

Instance Method Details

#get_features ⇒ Object

# File 'lib/nswtopo/layer/declination.rb', line 17

def get_features
  @params["fill"] ||= @params["stroke"]
  declination = @angle || @map.declination
  col_spacing = 0.001 * @map.scale * @spacing
  row_spacing = 0.001 * @map.scale * @arrows * 0.5
  col_offset = 0.001 * @map.scale * (@offset % @spacing)

  radius = 0.5 * @map.bounds.transpose.distance
  j_max = (radius / col_spacing).ceil
  i_max = (radius / row_spacing).ceil

  collection = GeoJSON::Collection.new(@map.projection)
  (-j_max..j_max).each do |j|
    x = j * col_spacing + col_offset
    coordinates = [[x, -radius], [x, radius]].map do |point|
      point.rotate_by_degrees(-declination).plus(@map.centre)
    end
    collection.add_linestring coordinates
    (-i_max..i_max).reject(&j.even? ? :even? : :odd?).map do |i|
      [x, i * row_spacing].rotate_by_degrees(-declination).plus(@map.centre)
    end.each do |coordinates|
      collection.add_point coordinates, "rotation" => declination
    end
  end
  collection
end

#to_s ⇒ Object

# File 'lib/nswtopo/layer/declination.rb', line 44

def to_s
  lines = features.grep(GeoJSON::LineString)
  return @name if lines.none?
  line = lines.map(&:coordinates).max_by(&:distance)
  angle = 90 - 180 * Math::atan2(*line.difference.reverse) / Math::PI
  "%s: %i line%s at %.1f°%s" % [@name, lines.length, (?s unless lines.one?), angle.abs, angle > 0 ? ?E : angle < 0 ? ?W : nil]
end