lwgeom_from_encoded_polyline()

LWGEOM* lwgeom_from_encoded_polyline	(	const char *	encodedpolyline,
		int	precision
	)

Create an LWGEOM object from an Encoded Polyline representation.

Parameters

encodedpolyline

the Encoded Polyline input

Definition at line 32 of file lwin_encoded_polyline.c.

{
  LWGEOM *geom = NULL;
  POINTARRAY *pa = NULL;
  int length = strlen(encodedpolyline);
  int idx = 0;
        double scale = pow(10,precision);
 
  float latitude = 0.0f;
  float longitude = 0.0f;
 
  pa = ptarray_construct_empty(LW_FALSE, LW_FALSE, 1);
 
  while (idx < length) {
    POINT4D pt;
    char byte = 0;
 
    int res = 0;
    char shift = 0;
    do {
      byte = encodedpolyline[idx++] - 63;
      res |= (byte & 0x1F) << shift;
      shift += 5;
    } while (byte >= 0x20);
    float deltaLat = ((res & 1) ? ~(res >> 1) : (res >> 1));
    latitude += deltaLat;
 
    shift = 0;
    res = 0;
    do {
      byte = encodedpolyline[idx++] - 63;
      res |= (byte & 0x1F) << shift;
      shift += 5;
    } while (byte >= 0x20);
    float deltaLon = ((res & 1) ? ~(res >> 1) : (res >> 1));
    longitude += deltaLon;
 
    pt.x = longitude/scale;
    pt.y = latitude/scale;
        pt.m = pt.z = 0.0;
    ptarray_append_point(pa, &pt, LW_FALSE);
  }
 
  geom = (LWGEOM *)lwline_construct(4326, NULL, pa);
  lwgeom_add_bbox(geom);
 
  return geom;
}

References LW_FALSE, lwgeom_add_bbox(), lwline_construct(), POINT4D::m, precision, ptarray_append_point(), ptarray_construct_empty(), window::res, POINT4D::x, POINT4D::y, and POINT4D::z.

Referenced by do_encoded_polyline_test(), and line_from_encoded_polyline().

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