Class: GD::GIS::LayerGeoJSON

Inherits:
Object
  • Object
show all
Defined in:
lib/gd/gis/layer_geojson.rb

Overview

Loads GeoJSON files into renderable Feature objects.

This class is responsible for:

  • Parsing GeoJSON files

  • Normalizing coordinates across CRS definitions

  • Classifying features using an ontology

  • Producing Feature instances

All coordinates are normalized to WGS84 in [longitude, latitude] order.

Class Method Summary collapse

Class Method Details

.load(source) ⇒ Array<GD::GIS::Feature>

Loads a GeoJSON file and returns normalized features.

Parameters:

  • path (String) —

    path to GeoJSON file

Returns:

Raises:

  • (JSON::ParserError) —

    if the file is invalid JSON

  • (Errno::ENOENT) —

    if the file does not exist



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# File 'lib/gd/gis/layer_geojson.rb', line 28

def self.load(source)
  data = normalize_source(source)

  validate_geojson!(data)

  # 1) Detect CRS
  crs_name   = data["crs"]&.dig("properties", "name")
  normalizer = CRS::Normalizer.new(crs_name)

  # 2) Load ontology
  ontology = Ontology.new

  # 3) Normalize geometries + classify
  data["features"].map do |feature|
    geometry   = feature["geometry"]
    properties = feature["properties"] || {}

    raise ArgumentError, "Missing geometry" unless geometry
    raise ArgumentError, "Missing geometry type" unless geometry["type"]
    raise ArgumentError, "Missing coordinates" unless geometry["coordinates"]

    normalize_geometry!(geometry, normalizer)

    layer = ontology.classify(
      properties,
      geometry_type: geometry["type"]
    )

    Feature.new(geometry, properties, layer)
  end
end

.normalize_geometry!(geometry, normalizer) ⇒ void

This method returns an undefined value.

Normalizes a GeoJSON geometry in-place.

Supports 2D and 3D coordinate arrays. Any additional dimensions (e.g. Z) are preserved or ignored depending on the CRS normalizer.

Parameters:



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# File 'lib/gd/gis/layer_geojson.rb', line 98

def self.normalize_geometry!(geometry, normalizer)
  case geometry["type"]

  when "Point"
    geometry["coordinates"] =
      normalizer.normalize(geometry["coordinates"])

  when "LineString"
    geometry["coordinates"] =
      geometry["coordinates"].map { |c| normalizer.normalize(c) }

  when "MultiLineString"
    geometry["coordinates"] =
      geometry["coordinates"].map do |line|
        line.map { |c| normalizer.normalize(c) }
      end

  when "Polygon"
    geometry["coordinates"] =
      geometry["coordinates"].map do |ring|
        ring.map { |c| normalizer.normalize(c) }
      end

  when "MultiPolygon"
    geometry["coordinates"] =
      geometry["coordinates"].map do |poly|
        poly.map do |ring|
          ring.map { |c| normalizer.normalize(c) }
        end
      end
  end
end

.normalize_source(source) ⇒ Object 



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# File 'lib/gd/gis/layer_geojson.rb', line 60

def self.normalize_source(source)
  case source
  when Hash
    source

  when String
    begin
      JSON.parse(source)
    rescue JSON::ParserError
      raise ArgumentError, "File not found: #{source}" unless File.exist?(source)

      JSON.parse(File.read(source))
    end

  else
    raise ArgumentError, "Unsupported GeoJSON source: #{source.class}"
  end
end

.validate_geojson!(data) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/gd/gis/layer_geojson.rb', line 79

def self.validate_geojson!(data)
  raise ArgumentError, "GeoJSON must be an object" unless data.is_a?(Hash)

  raise ArgumentError, "Only FeatureCollection is supported" unless data["type"] == "FeatureCollection"

  return if data["features"].is_a?(Array)

  raise ArgumentError, "GeoJSON must contain features array"
end