def write_point_attributes(self, fow, frc, bear, lfrcnp, reserved):
"""Writes 2 bytes point attributes to the stream
Parameters
----------
fow :
form of way (3 bits)
frc : int
functional road class (3 bits)
bear : int
Bearing (5 bits)
lfrcnp : int
Lowest FRC to next point or offset flags (3 bits)
reserved : int
mostly reserved for future use or Orientation/SideOfRoad (2 bits)
"""
if bear < 0 or bear >= 360:
raise ValueError(
"Bearing angle requires 0 <= x < 360 but %s is given" % bear
)
bear = (bear - BEAR_SECTOR / 2) / BEAR_SECTOR
bear = j_round(bear)
fow = fow & 0b111
frc = frc & 0b111
bear = bear & 0b11111
lfrcnp = lfrcnp & 0b111
reserved = reserved & 0b11
byte_int = fow + (frc << 3) + (reserved << 6)
self.write(int_to_bytes(byte_int, size=1, signed=False))
byte_int = bear + (lfrcnp << 5)
self.write(int_to_bytes(byte_int, size=1, signed=False))
def _create_offset_el(doc, el_loc):
if el_loc.poffs > 0:
poffs = j_round(float(el_loc.points[0].dnp) * el_loc.poffs)
else:
poffs = 0
if hasattr(el_loc, "noffs") and el_loc.noffs > 0:
noffs = j_round(float(el_loc.points[-2].dnp) * el_loc.noffs)
else:
noffs = 0
el_offset = doc.createElement("Offsets")
el_offset.appendChild(_create_data_el(doc, "PosOff", poffs))
el_offset.appendChild(_create_data_el(doc, "NegOff", noffs))
return el_offset
def write_coords_relative(self, lon, lat, prev_lon, prev_lat):
"""Writes the relative coordinates to the stream, 4 bytes
Parameters
----------
lon : float
Longitude to be written
lat : float
Latitude to be written
prev_lon : float
Previous Longitude
prev_lat : float
Previous Latitude
"""
rel_lon = j_round(DECA_MICRO_DEG_FACTOR * (lon - prev_lon))
rel_lat = j_round(DECA_MICRO_DEG_FACTOR * (lat - prev_lat))
self.write(int_to_bytes(rel_lon, size=2) + int_to_bytes(rel_lat, size=2))
def write_dnp(self, dnp):
"""Writes distance to next point to the stream, 1 byte
Parameters
----------
dnp : int
distance to next point
"""
interval = float(dnp) / DISTANCE_PER_INTERVAL - 0.5
interval = j_round(interval)
self.write(int_to_bytes(interval, size=1, signed=False))
def read_dnp(self):
"""Reads distance to next point from the buffer, 1 byte
Returns
-------
dnp : int
Distance to next point
"""
interval = bytes_to_int(self.read(1), signed=False)
dnp = (float(interval) + 0.5) * DISTANCE_PER_INTERVAL
dnp = j_round(dnp)
return dnp
def write_offset(self, offset):
"""Writes offset rate to the stream, 1 byte
Parameters
----------
offset : float
offset rate in [0,1] range
"""
if offset < 0 or offset >= 1:
raise ValueError("offset requires 0 <= x < 1 but %s is given" % offset)
elif offset == 0:
bucket_index = 0
else:
bucket_index = float(offset) * 256 - 0.5
bucket_index = j_round(bucket_index)
self.write(int_to_bytes(bucket_index, size=1, signed=False))
def deg_to_int(deg, resolution=24):
r"""converts degree coordinate into integer
.. math::
\mathrm{int} = 0.5 \times \mathop{\mathrm{sgn}}(\mathrm{deg}) +
\frac{\mathrm{deg} \times 2^{\mathrm{resolution}}}{360^{\circ}}
Parameters
----------
deg : float
Coordinate Degree
resolution: int
Resolution bits of this integer, default: 3 bytes = 24
Returns
-------
val : int
Coordinate value in integer
"""
val = sgn(deg) * 0.5 + float(deg * (1 << resolution)) / 360.0
return j_round(val)
def read_point_attributes(self):
"""Reads point attributes from the buffer, 2 bytes
Returns
-------
fow : int
form of way (3 bits)
frc : int
functional road class (3 bits)
bear : int
Bearing (5 bits)
lfrcnp : int
Lowest FRC to next point or offset flags (3 bits)
reserved : int
mostly reserved for future use or Orientation/SideOfRoad (2 bits)
"""
first_b, second_b = self.read(2)
fow = first_b & 0b111
frc = (first_b >> 3) & 0b111
reserved = (first_b >> 6) & 0b11
bear = (second_b & 0b11111) * BEAR_SECTOR + BEAR_SECTOR / 2
bear = j_round(bear)
lfrcnp = (second_b >> 5) & 0b111
return fow, frc, bear, lfrcnp, reserved