convert.py

import sys, getopt, os
from osgeo import ogr, gdal

def main(argv):
  inputfile = ''
  outputfile = ''
  point = ''
  try:
    opts, args = getopt.getopt(argv, "hi:o:p:", ["input=", "output=", "point="])
  except getopt.GetoptError:
    print('convert.py -i input.dxf -o output.geojson -p lat,lng')
    sys.exit(2)
  for opt, arg in opts:
    if opt == '-h':
      print('convert.py -i input.dxf -o output.geojson -p lat,lng')
      sys.exit()
    elif opt in ("-i", "--input"):
      inputfile = arg
    elif opt in ("-o", "--output"):
      outputfile = arg
    elif opt in ("-p", "--point"):
      point = arg

  point_parts = point.split(",")
  lng = float(point_parts[0])
  lat = float(point_parts[1])
  min_x, max_x, min_y, max_y = get_extent(inputfile)

  aspect_ratio = (max_x - min_x) / (max_y - min_y)
  reference_size = 0.001

  input_bbox = {
    'min_x': min_x,
    'max_x': max_x,
    'min_y': min_y,
    'max_y': max_y
  }
  output_bbox = {
    'min_x': lng - reference_size * aspect_ratio,
    'max_x': lng + reference_size * aspect_ratio,
    'min_y': lat - (reference_size / aspect_ratio),
    'max_y': lat + reference_size / aspect_ratio
  }

  export_geojson(inputfile, outputfile, input_bbox, output_bbox)

def get_extent(inputfile):
  gdal.SetConfigOption("DXF_FEATURE_LIMIT_PER_BLOCK", "-1")
  datasource = ogr.Open(inputfile)
  layer = datasource.GetLayer()
  return layer.GetExtent()

def export_geojson(input_file, output_file, input_bbox, output_bbox):
  command = """
  ogr2ogr -f GeoJSON \
  -gcp {input_min_x} {input_min_y} {output_min_x} {output_min_y} \
  -gcp {input_max_x} {input_min_y} {output_max_x} {output_min_y} \
  -gcp {input_min_x} {input_max_y} {output_min_x} {output_max_y} \
  -gcp {input_max_x} {input_max_y} {output_max_x} {output_max_y} \
  --config DXF_FEATURE_LIMIT_PER_BLOCK -1 \
  {output_file} \
  {input_file}
  """.format(
    input_file=input_file, 
    output_file=output_file, 
    input_min_x=input_bbox['min_x'],
    input_max_x=input_bbox['max_x'],
    input_min_y=input_bbox['min_y'],
    input_max_y=input_bbox['max_y'],
    output_min_x=output_bbox['min_x'],
    output_max_x=output_bbox['max_x'],
    output_min_y=output_bbox['min_y'],
    output_max_y=output_bbox['max_y']
  )
  os.system(command)

if __name__ == "__main__":
  main(sys.argv[1:])