def test_read_bitshort():
bs = BitStream(b"\xe0")
assert bs.read_bit_short() == 256 # 11
assert bs.read_bit_short() == 0 # 10
bs = BitStream(b"\x00\xff\xff")
bs.read_bits(6)
assert bs.read_bit_short() == -1
assert BitStream(b"\x7f\x00").read_bit_short() == 252
def load_classes(self) -> Iterable[Tuple[int, DXFClass]]:
sentinel = self.data[:SENTINEL_SIZE]
if (
sentinel
!= b"\x8D\xA1\xC4\xB8\xC4\xA9\xF8\xC5\xC0\xDC\xF4\x5F\xE7\xCF\xB6\x8A"
):
raise DwgCorruptedClassesSection(
"Sentinel for start of CLASSES section not found."
)
start_index = SENTINEL_SIZE
bs = BitStream(
self.data[start_index:],
dxfversion=self.specs.version,
encoding=self.specs.encoding,
)
class_data_size = bs.read_unsigned_long() # data size in bytes
end_sentinel_index = SENTINEL_SIZE + 6 + class_data_size
end_index = end_sentinel_index - 2
end_bit_index = (3 + class_data_size) << 3
while bs.bit_index < end_bit_index:
class_num = bs.read_bit_short()
dxfattribs = {
"flags": bs.read_bit_short(), # version?
"app_name": bs.read_text(),
"cpp_class_name": bs.read_text(),
"name": bs.read_text(),
"was_a_proxy": bs.read_bit(),
"is_an_entity": int(bs.read_bit_short() == 0x1F2),
}
yield class_num, DXFClass.new(dxfattribs=dxfattribs)
if self.crc_check and False:
check = struct.unpack_from("<H", self.data, end_index)[0]
# TODO: classes crc check
# Which data should be checked? This is not correct:
crc = crc8(self.data[start_index:end_index])
if check != crc:
raise CRCError("CRC error in classes section.")
sentinel = self.data[
end_sentinel_index : end_sentinel_index + SENTINEL_SIZE
]
if (
sentinel
!= b"\x72\x5E\x3B\x47\x3B\x56\x07\x3A\x3F\x23\x0B\xA0\x18\x30\x49\x75"
):
raise DwgCorruptedClassesSection(
"Sentinel for end of CLASSES section not found."
)
def classes_R2000(self) -> None:
seeker, section_size = self.specs.sections[CLASSES_ID]
sentinel = self.data[seeker:seeker + SENTINEL_SIZE]
if sentinel != b'\x8D\xA1\xC4\xB8\xC4\xA9\xF8\xC5\xC0\xDC\xF4\x5F\xE7\xCF\xB6\x8A':
raise DwgCorruptedClassesSection(
'Sentinel for start of section not found.')
cls_tag = DXFTag(0, 'CLASS')
classes = self.sections['CLASSES']
bs = BitStream(
self.data[seeker + SENTINEL_SIZE:seeker + section_size],
dxfversion=self.specs.version,
encoding=self.specs.encoding,
)
class_data_size = bs.read_unsigned_long() # data size in bytes
end_index = (3 + class_data_size) << 3
while bs.bit_index < end_index:
class_num = bs.read_bit_short()
flags = bs.read_bit_short() # version?
app_name = bs.read_text()
cpp_class_name = bs.read_text()
class_dxf_name = bs.read_text()
was_a_zombie = bs.read_bit()
item_class_id = bs.read_bit_short()
# print((class_num, flags, app_name, class_dxf_name, cpp_class_name, was_a_zombie, item_class_id))
classes.append(
Tags([
cls_tag,
DXFTag(1, class_dxf_name),
DXFTag(2, cpp_class_name),
DXFTag(3, app_name),
DXFTag(90, flags),
DXFTag(280, was_a_zombie),
DXFTag(281, 1 if item_class_id == 0x1f2 else 0)
]))
self.dxf_object_types[class_num] = class_dxf_name
# Ignore crc for the sake of speed.
# _index = index + (20 + class_data_size)
# crc = struct.unpack_from('<h', self.data, index)
_index = seeker + (SENTINEL_SIZE + 6 + class_data_size)
sentinel = self.data[_index:_index + SENTINEL_SIZE]
if sentinel != b'\x72\x5E\x3B\x47\x3B\x56\x07\x3A\x3F\x23\x0B\xA0\x18\x30\x49\x75':
raise DwgCorruptedClassesSection(
'Sentinel for end of section not found.')
def lwpolyline(self, data: bytes):
# OpenDesign Specs LWPLINE: 20.4.85 Page 211
logger.warning(
'Untested proxy graphic entity: LWPOLYLINE - Need examples!')
bs = BitStream(data)
flag = bs.read_bit_short()
attribs = self._build_dxf_attribs()
if flag & 4:
attribs['const_width'] = bs.read_bit_double()
if flag & 8:
attribs['elevation'] = bs.read_bit_double()
if flag & 2:
attribs['thickness'] = bs.read_bit_double()
if flag & 1:
attribs['extrusion'] = Vec3(bs.read_bit_double(3))
num_points = bs.read_bit_long()
if flag & 16:
num_bulges = bs.read_bit_long()
else:
num_bulges = 0
if self.dxfversion >= 'AC1024': # R2010+
vertex_id_count = bs.read_bit_long()
else:
vertex_id_count = 0
if flag & 32:
num_width = bs.read_bit_long()
else:
num_width = 0
# ignore DXF R13/14 special vertex order
vertices = [bs.read_raw_double(2)]
prev_point = vertices[-1]
for _ in range(num_points - 1):
x = bs.read_bit_double_default(default=prev_point[0])
y = bs.read_bit_double_default(default=prev_point[1])
prev_point = (x, y)
vertices.append(prev_point)
bulges = [bs.read_bit_double() for _ in range(num_bulges)]
vertex_ids = [bs.read_bit_long() for _ in range(vertex_id_count)]
widths = [(bs.read_bit_double(), bs.read_bit_double())
for _ in range(num_width)]
if len(bulges) == 0:
bulges = list(repeat(0, num_points))
if len(widths) == 0:
widths = list(repeat((0, 0), num_points))
points = []
for v, w, b in zip(vertices, widths, bulges):
points.append((v[0], v[1], w[0], w[1], b))
lwpolyline = cast('LWPolyline',
self._factory('LWPOLYLINE', dxfattribs=attribs))
lwpolyline.set_points(points)
return lwpolyline
