class EsriShapefile::Reader
Constants
- MAIN_FILE_HEADER_BYTESIZE
- RECORD_HEADER_BYTESIZE
Attributes
main_file_header[R]
Public Class Methods
new(path_to_shapefile)
click to toggle source
# File lib/esri_shapefile/reader.rb, line 12 def initialize(path_to_shapefile) @path_to_shapefile = Pathname.new(path_to_shapefile) @path_to_dbf = @path_to_shapefile.sub_ext(".dbf") @main_file_header = parse_main_file_header end
Public Instance Methods
each_record() { |record_header, shape| ... }
click to toggle source
# File lib/esri_shapefile/reader.rb, line 19 def each_record dbf = @path_to_dbf.file? ? DBF::Table.new(@path_to_dbf.to_s) : nil File.open(@path_to_shapefile) do |file| file.pos = MAIN_FILE_HEADER_BYTESIZE (0..Float::INFINITY).lazy.reduce(file.pos) do |current_offset, _| break if current_offset >= main_file_header.file_length_bytes record_header_bytes = file.read(RECORD_HEADER_BYTESIZE) record_header = RecordHeader.from_bytes(record_header_bytes) shape_bytes = file.read(record_header.content_length_bytes) shape_class = Shapes.find_by_bytes(shape_bytes) shape = shape_class.from_bytes(shape_bytes) shape.metadata = get_record_metadata(dbf, record_header.record_number) yield record_header, shape file.pos end end end
Private Instance Methods
get_record_metadata(dbf, record_number)
click to toggle source
Retrieve the metadata for the shape from the associated .dbf file. Record numbers are one based, while the dbf file reader is 0 based. So we subtract one from the record number when performing the lookup.
# File lib/esri_shapefile/reader.rb, line 49 def get_record_metadata(dbf, record_number) dbf.nil? ? {} : dbf.find(record_number - 1).attributes end
parse_main_file_header()
click to toggle source
# File lib/esri_shapefile/reader.rb, line 53 def parse_main_file_header main_file_header_bytes = File.binread(@path_to_shapefile, 100, 0) MainFileHeader.from_bytes(main_file_header_bytes) end