Class: MapnikLegendary::Geometry

Inherits:
Object
  • Object
show all
Defined in:
lib/mapnik_legendary/geometry.rb

Instance Method Summary collapse

Constructor Details

#initialize(type, zoom, map) ⇒ Geometry

Returns a new instance of Geometry.



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# File 'lib/mapnik_legendary/geometry.rb', line 5

def initialize(type, zoom, map)
  proj = Mapnik::Projection.new(map.srs)
  width_of_world_in_pixels = 2**zoom * 256
  width_of_world_in_metres = proj.forward(Mapnik::Coord2d.new(180, 0)).x - proj.forward(Mapnik::Coord2d.new(-180, 0)).x
  width_of_image_in_metres = map.width.to_f / width_of_world_in_pixels * width_of_world_in_metres
  height_of_image_in_metres = map.height.to_f / width_of_world_in_pixels * width_of_world_in_metres

  @max_x = width_of_image_in_metres
  @max_y = height_of_image_in_metres
  @min_x = 0
  @min_y = 0

  @geom = case type
          when 'point' then "POINT(#{@max_x / 2} #{@max_y / 2})"
          when 'point75' then "POINT(#{@max_x * 0.5} #{@max_y * 0.75})"
          when 'polygon' then "POLYGON((0 0, #{@max_x} 0, #{@max_x} #{@max_y}, 0 #{@max_y}, 0 0))"
          when 'linestring-with-gap' then "MULTILINESTRING((0 0, #{@max_x * 0.45} #{@max_y * 0.45}),(#{@max_x * 0.55} #{@max_y * 0.55},#{@max_x} #{@max_y}))"
          when 'polygon-with-hole' then "POLYGON((#{0.7 * @max_x} #{0.2 * @max_y}, #{0.9 * @max_x} #{0.9 * @max_y}" +
                                        ", #{0.3 * @max_x} #{0.8 * @max_y}, #{0.2 * @max_x} #{0.4 * @max_y}" +
                                        ", #{0.7 * @max_y} #{0.2 * @max_y}),( #{0.4 * @max_x} #{0.6 * @max_y}" +
                                        ", #{0.7 * @max_x} #{0.7 * @max_y}, #{0.6 * @max_x} #{0.4 * @max_y}" +
                                        ", #{0.4 * @max_x} #{0.6 * @max_y}))"
          else "LINESTRING(0 0, #{@max_x} #{@max_y})"
          end
end

Instance Method Details

#envelope ⇒ Object 



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# File 'lib/mapnik_legendary/geometry.rb', line 35

def envelope
  Mapnik::Envelope.new(@min_x, @min_y, @max_x, @max_y)
end

#to_csv ⇒ Object 



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# File 'lib/mapnik_legendary/geometry.rb', line 31

def to_csv
  %("#{@geom}")
end