def __init__(self, arg, multifile=True, filesize=None, detectmosaic=True):
"""Open CZI file and read header.
Raise ValueError if file is not a ZISRAW file.
Parameters
----------
multifile : bool
If True (default), the master file of a multifile CZI file
will be opened if applicable.
filesize : int
Size of file if arg is a file handle pointing to an
embedded CZI file.
detectmosaic : bool
If True (default), mosaic images will be reconstructed from
SubBlocks with a tile index.
Notes
-----
CziFile instances created from file name must be closed using the
'close' method, which is automatically called when using the
'with' statement.
"""
self._fh = FileHandle(arg, size=filesize)
try:
if self._fh.read(10) != b'ZISRAWFILE':
raise ValueError("not a CZI file")
self.header = Segment(self._fh, 0).data()
except Exception:
self._fh.close()
raise
if multifile and self.header.file_part and isinstance(arg, basestring):
# open master file instead
self._fh.close()
name, _ = match_filename(arg)
self._fh = FileHandle(name)
self.header = Segment(self._fh, 0).data()
assert (self.header.primary_file_guid == self.header.file_guid)
assert (self.header.file_part == 0)
if self.header.update_pending:
warnings.warn("file is pending update")
self._filter_mosaic = detectmosaic
