Class: OGR::DataSource

Inherits:
Object
  • Object
show all
Includes:
FFIOGR
Defined in:
lib/ffi-ogr/data_source.rb

Direct Known Subclasses

CSV, GeoJSON, KML, Shapefile

Constant Summary

Constants included from FFIOGR

FFIOGR::OGR_FUNCTIONS

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from FFIOGR

find_lib, gdal_library_path, search_paths

Constructor Details

#initialize(ptr) ⇒ DataSource

Returns a new instance of DataSource.



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# File 'lib/ffi-ogr/data_source.rb', line 7

def initialize(ptr)
  @ptr = FFI::AutoPointer.new(ptr, self.class.method(:release))
  @ptr.autorelease = false
end

Instance Attribute Details

#ptr ⇒ Object

Returns the value of attribute ptr.



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# File 'lib/ffi-ogr/data_source.rb', line 5

def ptr
  @ptr
end

Class Method Details

.release(ptr) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 12

def self.release(ptr);end

Instance Method Details

#add_layer(name, geometry_type, spatial_ref = nil, options = nil) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 97

def add_layer(name, geometry_type, spatial_ref=nil, options=nil)
  layer = FFIOGR.OGR_DS_CreateLayer(@ptr, name, spatial_ref, geometry_type.to_sym, options)
  OGR::Tools.cast_layer(layer)
end

#copy(driver_name, output_path, driver_options = nil) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 18

def copy(driver_name, output_path, driver_options=nil)
  driver = OGRGetDriverByName driver_name
  new_ds = FFIOGR.OGR_Dr_CopyDataSource(driver, @ptr, File.expand_path(output_path), driver_options)
  FFIOGR.OGR_DS_Destroy(new_ds)
end

#copy_with_transform(driver_name, output_path, spatial_ref = nil, driver_options = nil) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 24

def copy_with_transform(driver_name, output_path, spatial_ref=nil, driver_options=nil)
  writer = OGR::Writer.new driver_name
  writer.set_output(output_path)
  out = writer.ptr

  layers.each do |layer|
    name = layer.name
    geometry_type = layer.geometry_type
    old_sr = layer.spatial_ref

    ct = OGR::CoordinateTransformation.find_transformation(old_sr, spatial_ref) unless spatial_ref.nil? || (spatial_ref == old_sr)

    sr = spatial_ref.nil? ? nil : spatial_ref.ptr

    new_layer = out.add_layer name, geometry_type, sr, driver_options

    ptr = layer.ptr

    layer_definition = FFIOGR.OGR_L_GetLayerDefn(ptr)
    field_count = FFIOGR.OGR_FD_GetFieldCount(layer_definition)

    for i in (0...field_count)
      fd = FFIOGR.OGR_FD_GetFieldDefn(layer_definition, i)
      name = FFIOGR.OGR_Fld_GetNameRef(fd)
      type = FFIOGR.OGR_Fld_GetType(fd)

      opts = {}.tap do |o|
        case type
        when :real
          o[:precision] = FFIOGR.OGR_Fld_GetPrecision fd
        when :string
          o[:width] = FFIOGR.OGR_Fld_GetWidth fd
        end
      end

      new_layer.add_field name, type, opts
    end

    layer.features.each do |feature|
      geometry = OGR::Tools.cast_geometry(feature.geometry)
      geometry.transform ct if ct

      new_feature = new_layer.create_feature
      new_feature.add_geometry geometry

      ptr = feature.ptr
      field_count = FFIOGR.OGR_F_GetFieldCount(ptr)

      for i in (0...field_count)
        fd = FFIOGR.OGR_F_GetFieldDefnRef(ptr, i)
        field_name = FFIOGR.OGR_Fld_GetNameRef(fd)
        field_type = FFIOGR.OGR_Fld_GetType(fd)

        case field_type
        when :integer
          field_value = FFIOGR.OGR_F_GetFieldAsInteger(ptr, i)
        when :real
          field_value = FFIOGR.OGR_F_GetFieldAsDouble(ptr, i)
        else
          field_value = FFIOGR.OGR_F_GetFieldAsString(ptr, i)
        end

        new_feature.set_field_value field_name, field_value, field_type
      end

      new_layer.add_feature new_feature
    end

    new_layer.sync
  end
  out.free
end

#free ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 14

def free
  FFIOGR.OGR_DS_Destroy(@ptr)
end

#get_features ⇒ Object Also known as: features 



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# File 'lib/ffi-ogr/data_source.rb', line 117

def get_features
  layers.map {|l| l.features}
end

#get_fields ⇒ Object Also known as: fields 



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# File 'lib/ffi-ogr/data_source.rb', line 131

def get_fields
  features.map {|feature| feature.map {|f| f.fields}}
end

#get_geometries(as_geojson = false) ⇒ Object Also known as: geometries 



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# File 'lib/ffi-ogr/data_source.rb', line 122

def get_geometries(as_geojson=false)
  unless as_geojson
    features.map {|feature| feature.map {|f| OGR::Tools.cast_geometry(f.geometry)}}
  else
    features.map {|feature| feature.map {|f| OGR::Tools.cast_geometry(f.geometry).to_geojson}}
  end
end

#get_layers ⇒ Object Also known as: layers 



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# File 'lib/ffi-ogr/data_source.rb', line 106

def get_layers
  layers = []

  for i in (0...num_layers) do
    layers << OGR::Tools.cast_layer(OGR_DS_GetLayer(@ptr, i))
  end

  layers
end

#num_layers ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 102

def num_layers
  FFIOGR.OGR_DS_GetLayerCount(@ptr)
end

#parse_driver_options(options) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 176

def parse_driver_options(options)
  tf_values = {
    true => "YES",
    false => "NO"
  }

  pointers = [].tap do |ptrs|
    options.each do |k,v|
      tf_value = tf_values[v] || v
      ptrs << FFI::MemoryPointer.from_string("#{k.to_s.upcase}=#{tf_value.upcase}")
    end
  end

  pointers << nil

  driver_options = FFI::MemoryPointer.new :pointer, pointers.size

  pointers.each_with_index do |ptr, i|
    driver_options[i].put_pointer 0, ptr
  end

  driver_options
end

#to_csv(output_path, options = {}) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 160

def to_csv(output_path, options={})
  to_format('csv', output_path)
end

#to_format(format, output_path, options = {}) ⇒ Object

Raises:

  • (RuntimeError) 


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# File 'lib/ffi-ogr/data_source.rb', line 136

def to_format(format, output_path, options={})
  raise RuntimeError.new("Output path not specified.") if output_path.nil?

  spatial_ref = options.delete :spatial_ref

  driver_options = parse_driver_options options

  driver_name = OGR::DRIVER_TYPES[format]

  unless spatial_ref
    copy driver_name, output_path, driver_options
  else
    if spatial_ref.instance_of? OGR::SpatialReference
      copy_with_transform driver_name, output_path, spatial_ref, driver_options
    else
      raise RuntimeError.new("Invalid spatial reference specified.")
    end
  end
end

#to_geojson(output_path, options = {}) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 172

def to_geojson(output_path, options={})
  to_format('geojson', output_path, options)
end

#to_json(pretty = false) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 200

def to_json(pretty=false)
  h = {
    type: 'FeatureCollection',
    features: []
  }

  layers.each do |layer|
    h[:features].tap do |features|
      layer.features.each do |feature|
        features << {
          type: 'Feature',
          geometry: OGR::Tools.cast_geometry(feature.geometry).to_geojson,
          properties: feature.fields
        }
      end
    end
  end

  unless pretty
    MultiJson.dump(h)
  else
    MultiJson.dump(h, pretty: true)
  end
end

#to_kml(output_path, options = {}) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 164

def to_kml(output_path, options={})
  format = OGR.drivers.include?('LIBKML') ? 'kml' : 'kml_lite'

  warn "GDAL is compiled without LIBKML support. Without LIBKML support KML output will always be in EPSG:4326" if format == 'kml_lite'

  to_format(format, output_path, options)
end

#to_shp(output_path, options = {}) ⇒ Object 



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# File 'lib/ffi-ogr/data_source.rb', line 156

def to_shp(output_path, options={})
  to_format('shapefile', output_path)
end