Class: Charta::Geometry

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

Overview

Represents a Geometry with SRID

Direct Known Subclasses

GeometryCollection, LineString, Point, Polygon

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(feature, properties = {}) ⇒ Geometry

Returns a new instance of Geometry.



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# File 'lib/charta/geometry.rb', line 8

def initialize(feature, properties = {})
  @feature = feature
  @properties = properties
  # raise ArgumentError, 'Need EWKT to instantiate Geometry' if @ewkt.to_s =~ /\A[[:space:]]*\z/
end

Class Method Details

.factory(srid = 4326) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 247

def factory(srid = 4326)
  return projected_factory(srid) if srid.to_i == 4326
  geos_factory(srid)
end

.feature(ewkt_or_rgeo) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 252

def feature(ewkt_or_rgeo)
  return from_rgeo(ewkt_or_rgeo) if ewkt_or_rgeo.is_a? RGeo::Feature::Instance
  from_ewkt(ewkt_or_rgeo)
end

.srs_database ⇒ Object 



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# File 'lib/charta/geometry.rb', line 243

def srs_database
  @srs_database ||= RGeo::CoordSys::SRSDatabase::Proj4Data.new('epsg', authority: 'EPSG', cache: true)
end

Instance Method Details

#!=(other) ⇒ Object

Test if the other measure is equal to self



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# File 'lib/charta/geometry.rb', line 104

def !=(other)
  other_geometry = Charta.new_geometry(other).transform(srid)
  return true if empty? && other_geometry.empty?
  return inspect == other_geometry.inspect if collection? && other_geometry.collection?
  !@feature.equals?(other_geometry.feature)
end

#==(other) ⇒ Object

Test if the other measure is equal to self



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# File 'lib/charta/geometry.rb', line 96

def ==(other)
  other_geometry = Charta.new_geometry(other).transform(srid)
  return true if empty? && other_geometry.empty?
  return inspect == other_geometry.inspect if collection? && other_geometry.collection?
  @feature.equals?(other_geometry.feature)
end

#area ⇒ Object

Returns area in unit corresponding to the SRS



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# File 'lib/charta/geometry.rb', line 117

def area
  surface? ? @feature.area : 0
end

#bounding_box ⇒ Object 



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# File 'lib/charta/geometry.rb', line 212

def bounding_box
  unless defined? @bounding_box
    bbox = RGeo::Cartesian::BoundingBox.create_from_geometry(@feature)
    instance_variable_set('@x_min', bbox.min_x || 0)
    instance_variable_set('@y_min', bbox.min_y || 0)
    instance_variable_set('@x_max', bbox.max_x || 0)
    instance_variable_set('@y_max', bbox.max_y || 0)
    @bounding_box = BoundingBox.new(@y_min, @x_min, @y_max, @x_max)
  end
  @bounding_box
end

#buffer(radius) ⇒ Object

Produces buffer



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# File 'lib/charta/geometry.rb', line 191

def buffer(radius)
  @feature.buffer(radius)
end

#centroid ⇒ Object

Computes the geometric center of a geometry, or equivalently, the center of mass of the geometry as a POINT.



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# File 'lib/charta/geometry.rb', line 130

def centroid
  return nil unless surface? && !@feature.is_empty?
  point = @feature.centroid
  [point.y, point.x]
end

#collection? ⇒ Boolean

Returns the type of the geometry as a string. EG: ‘ST_Linestring’, ‘ST_Polygon’, ‘ST_MultiPolygon’ etc. This function differs from GeometryType(geometry) in the case of the string and ST in front that is returned, as well as the fact that it will not indicate whether the geometry is measured.

Returns:

  • (Boolean) 


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# File 'lib/charta/geometry.rb', line 28

def collection?
  @feature.geometry_type == RGeo::Feature::GeometryCollection
end

#convert_to(new_type) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 143

def convert_to(new_type)
  case new_type
  when type then self
  when :multi_point then flatten_multi(:point)
  when :multi_line_string then flatten_multi(:line_string)
  when :multi_polygon then flatten_multi(:polygon)
  end
end

#difference(other) ⇒ Object Also known as: - 



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# File 'lib/charta/geometry.rb', line 206

def difference(other)
  other_geometry = Charta.new_geometry(other).transform(srid)
  @feature.difference(other_geometry.feature)
end

#empty? ⇒ Boolean Also known as: blank?

Returns true if this Geometry is an empty geometrycollection, polygon, point etc.

Returns:

  • (Boolean) 


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# File 'lib/charta/geometry.rb', line 123

def empty?
  @feature.is_empty?
end

#ewkt ⇒ Object 



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# File 'lib/charta/geometry.rb', line 55

def ewkt
  puts 'DEPRECATION WARNING: Charta::Geometry.ewkt is deprecated. Please use Charta::Geometry.to_ewkt instead'
  to_ewkt
end

#feature ⇒ Object 



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# File 'lib/charta/geometry.rb', line 234

def feature
  @feature
end

#find_srid(name_or_srid) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 230

def find_srid(name_or_srid)
  Charta.find_srid(name_or_srid)
end

#flatten_multi(as_type) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 152

def flatten_multi(as_type)
  items = []
  as_multi_type = "multi_#{as_type}".to_sym
  if type == as_type
    items << @feature
  elsif type == :geometry_collection
    @feature.each do |geom|
      type_name = Charta.underscore(geom.geometry_type.type_name).to_sym
      if type_name == as_type
        items << geom
      elsif type_name == as_multi_type
        geom.each do |item|
          items << item
        end
      end
    end
  end
  Charta.new_geometry(@feature.factory.send(as_multi_type, items))
end

#inspect ⇒ Object 



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# File 'lib/charta/geometry.rb', line 14

def inspect
  "<#{self.class.name}(#{to_ewkt})>"
end

#intersection(other) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 201

def intersection(other)
  other_geometry = Charta.new_geometry(other).transform(srid)
  @feature.intersection(other_geometry.feature)
end

#merge(other) ⇒ Object Also known as: + 



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# File 'lib/charta/geometry.rb', line 195

def merge(other)
  other_geometry = Charta.new_geometry(other).transform(srid)
  @feature.union(other_geometry.feature)
end

#point_on_surface ⇒ Object

Returns a POINT guaranteed to lie on the surface.



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# File 'lib/charta/geometry.rb', line 137

def point_on_surface
  return nil unless surface?
  point = @feature.point_on_surface
  [point.y, point.x]
end

#srid ⇒ Object

Return the spatial reference identifier for the ST_Geometry



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# File 'lib/charta/geometry.rb', line 33

def srid
  @feature.srid.to_i
end

#surface? ⇒ Boolean

Returns true if Geometry is a Surface

Returns:

  • (Boolean) 


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# File 'lib/charta/geometry.rb', line 112

def surface?
  [RGeo::Feature::Polygon, RGeo::Feature::MultiPolygon].include? @feature.geometry_type
end

#to_binary ⇒ Object Also known as: to_ewkb

Return the Well-Known Binary (WKB) representation of the geometry with SRID meta data.



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# File 'lib/charta/geometry.rb', line 61

def to_binary
  generator = RGeo::WKRep::WKBGenerator.new(tag_format: :ewkbt, emit_ewkbt_srid: true)
  generator.generate(@feature)
end

#to_ewkt ⇒ Object Also known as: to_s

Returns EWKT: WKT with its SRID



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# File 'lib/charta/geometry.rb', line 50

def to_ewkt
  Charta.generate_ewkt(@feature).to_s
end

#to_geojson ⇒ Object Also known as: to_json

Return the geometry as a Geometry Javascript Object Notation (GeoJSON) element.



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# File 'lib/charta/geometry.rb', line 85

def to_geojson
  to_json_object.to_json
end

#to_json_feature(properties = {}) ⇒ Object 



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# File 'lib/charta/geometry.rb', line 238

def to_json_feature(properties = {})
  { type: 'Feature', properties: properties, geometry: to_json_object }
end

#to_json_object ⇒ Object

Returns object in JSON (Hash)



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# File 'lib/charta/geometry.rb', line 91

def to_json_object
  RGeo::GeoJSON.encode(@feature)
end

#to_rgeo ⇒ Object

Returns the underlaying object managed by Charta: the RGeo feature



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# File 'lib/charta/geometry.rb', line 38

def to_rgeo
  @feature
end

#to_svg(options = {}) ⇒ Object

Pas bien compris le fonctionnement



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# File 'lib/charta/geometry.rb', line 68

def to_svg(options = {})
  svg = '<svg xmlns="http://www.w3.org/2000/svg" version="1.1"'
  { preserve_aspect_ratio: 'xMidYMid meet',
    width: 180, height: 180,
    view_box: bounding_box.svg_view_box.join(' ') }.merge(options).each do |attr, value|
    svg << " #{Charta.camelcase(attr.to_s, :lower)}=\"#{value}\""
  end
  svg << "><path d=\"#{to_svg_path}\"/></svg>"
  svg
end

#to_svg_path ⇒ Object

Return the geometry as Scalar Vector Graphics (SVG) path data.



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# File 'lib/charta/geometry.rb', line 80

def to_svg_path
  RGeo::SVG.encode(@feature)
end

#to_text ⇒ Object Also known as: as_text, to_wkt

Returns the Well-Known Text (WKT) representation of the geometry/geography without SRID metadata



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# File 'lib/charta/geometry.rb', line 43

def to_text
  @feature.as_text.match(/\ASRID=.*;(.*)/)[1]
end

#transform(new_srid) ⇒ Object

Returns a new geometry with the coordinates converted into the new SRS



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# File 'lib/charta/geometry.rb', line 173

def transform(new_srid)
  return self if new_srid == srid
  raise 'Proj is not supported. Cannot tranform' unless RGeo::CoordSys::Proj4.supported?
  new_srid = Charta::SRS[new_srid] || new_srid
  database = self.class.srs_database
  new_proj_entry = database.get(new_srid)
  raise "Cannot find proj for SRID: #{new_srid}" if new_proj_entry.nil?
  new_feature = RGeo::CoordSys::Proj4.transform(
    database.get(srid).proj4,
    @feature,
    new_proj_entry.proj4,
    self.class.factory(new_srid)
  )
  generator = RGeo::WKRep::WKTGenerator.new(tag_format: :ewkt, emit_ewkt_srid: true)
  Charta.new_geometry(generator.generate(new_feature))
end

#type ⇒ Object

Returns the type of the geometry as a string. Example: point, multi_polygon, geometry_collection…



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# File 'lib/charta/geometry.rb', line 20

def type
  Charta.underscore(@feature.geometry_type.type_name).to_sym
end