Class: RGeo::Geographic::SimpleMercatorProjector

Inherits:
Object
  • Object
show all
Defined in:
lib/rgeo/geographic/simple_mercator_projector.rb

Overview

:nodoc:

Constant Summary collapse

EQUATORIAL_RADIUS = 
6378137.0

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(geography_factory_, opts_ = {}) ⇒ SimpleMercatorProjector

Returns a new instance of SimpleMercatorProjector.



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 47

def initialize(geography_factory_, opts_={})
  @geography_factory = geography_factory_
  @projection_factory = Cartesian.preferred_factory(:srid => 3785,
    :proj4 => SimpleMercatorProjector._proj4_3785,
    :coord_sys => SimpleMercatorProjector._coordsys_3785,
    :buffer_resolution => opts_[:buffer_resolution],
    :lenient_multi_polygon_assertions => opts_[:lenient_multi_polygon_assertions],
    :has_z_coordinate => opts_[:has_z_coordinate],
    :has_m_coordinate => opts_[:has_m_coordinate])
end

Class Method Details

._coordsys_3785 ⇒ Object

:nodoc:



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 144

def self._coordsys_3785  # :nodoc:
  unless defined?(@coordsys_3785)
    @coordsys_3785 = CoordSys::CS.create_from_wkt('PROJCS["Popular Visualisation CRS / Mercator",GEOGCS["Popular Visualisation CRS",DATUM["Popular_Visualisation_Datum",SPHEROID["Popular Visualisation Sphere",6378137,0,AUTHORITY["EPSG","7059"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6055"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4055"]],UNIT["metre",1,AUTHORITY["EPSG","9001"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],AUTHORITY["EPSG","3785"],AXIS["X",EAST],AXIS["Y",NORTH]]')
  end
  @coordsys_3785
end

._proj4_3785 ⇒ Object

:nodoc:



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 136

def self._proj4_3785  # :nodoc:
  unless defined?(@proj4_3785)
    @proj4_3785 = CoordSys::Proj4.create('+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs')
  end
  @proj4_3785
end

Instance Method Details

#limits_window ⇒ Object 



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 129

def limits_window
  @limits_window ||= ProjectedWindow.new(@geography_factory,
    -20037508.342789, -20037508.342789, 20037508.342789, 20037508.342789,
    :is_limits => true)
end

#project(geometry_) ⇒ Object 



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 64

def project(geometry_)
  case geometry_
  when Feature::Point
    rpd_ = ImplHelper::Math::RADIANS_PER_DEGREE
    radius_ = EQUATORIAL_RADIUS
    @projection_factory.point(geometry_.x * rpd_ * radius_,
      ::Math.log(::Math.tan(::Math::PI / 4.0 + geometry_.y * rpd_ / 2.0)) * radius_)
  when Feature::Line
    @projection_factory.line(project(geometry_.start_point), project(geometry_.end_point))
  when Feature::LinearRing
    @projection_factory.linear_ring(geometry_.points.map{ |p_| project(p_) })
  when Feature::LineString
    @projection_factory.line_string(geometry_.points.map{ |p_| project(p_) })
  when Feature::Polygon
    @projection_factory.polygon(project(geometry_.exterior_ring),
                                geometry_.interior_rings.map{ |p_| project(p_) })
  when Feature::MultiPoint
    @projection_factory.multi_point(geometry_.map{ |p_| project(p_) })
  when Feature::MultiLineString
    @projection_factory.multi_line_string(geometry_.map{ |p_| project(p_) })
  when Feature::MultiPolygon
    @projection_factory.multi_polygon(geometry_.map{ |p_| project(p_) })
  when Feature::GeometryCollection
    @projection_factory.collection(geometry_.map{ |p_| project(p_) })
  else
    nil
  end
end

#projection_factory ⇒ Object 



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 59

def projection_factory
  @projection_factory
end

#unproject(geometry_) ⇒ Object 



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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 94

def unproject(geometry_)
  case geometry_
  when Feature::Point
    dpr_ = ImplHelper::Math::DEGREES_PER_RADIAN
    radius_ = EQUATORIAL_RADIUS
    @geography_factory.point(geometry_.x / radius_ * dpr_,
      (2.0 * ::Math.atan(::Math.exp(geometry_.y / radius_)) - ::Math::PI / 2.0) * dpr_)
  when Feature::Line
    @geography_factory.line(unproject(geometry_.start_point), unproject(geometry_.end_point))
  when Feature::LinearRing
    @geography_factory.linear_ring(geometry_.points.map{ |p_| unproject(p_) })
  when Feature::LineString
    @geography_factory.line_string(geometry_.points.map{ |p_| unproject(p_) })
  when Feature::Polygon
    @geography_factory.polygon(unproject(geometry_.exterior_ring),
      geometry_.interior_rings.map{ |p_| unproject(p_) })
  when Feature::MultiPoint
    @geography_factory.multi_point(geometry_.map{ |p_| unproject(p_) })
  when Feature::MultiLineString
    @geography_factory.multi_line_string(geometry_.map{ |p_| unproject(p_) })
  when Feature::MultiPolygon
    @geography_factory.multi_polygon(geometry_.map{ |p_| unproject(p_) })
  when Feature::GeometryCollection
    @geography_factory.collection(geometry_.map{ |p_| unproject(p_) })
  else
    nil
  end
end

#wraps? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rgeo/geographic/simple_mercator_projector.rb', line 124

def wraps?
  true
end