PyQt cannot read all of the data the same way as in C++, because it cannot handle template classes (like QList<double> and QVector<QPointF>), which would require language-specific support that is not available in Python. This means a work-around must be used. Fortunately, the datastream format is quite straightforward, so reading arbitrary template classes can be reduced to a simple algorithm: read the length as a uint32, then iterate over a range and read the contained elements one-by-one into a list:
points = []
length = stream.readUInt32()
for index in range(length):
point = QPoint()
stream >> point
points.append(point)
Below is a script that shows how to read the whole dataset format correctly:
from PyQt4 import QtCore, QtGui
FLAG_HASSOURCE = 0x0001
FLAG_HASROLE = 0x0002
FLAG_HASCOLOR = 0x0004
FLAG_HASID = 0x0008
FLAG_COMPRESS = 0x0010
FLAG_HASTHRESHOLDS = 0x0020
FLAG_HASUNITS = 0x0040
FLAG_HASCREATORIDS = 0x0080
FLAG_HASHIDDEN = 0x0100
FLAG_HASMETADATA = 0x0200
MAGIC_NUMBER = 0x46474247
FILE_VERSION = 1
DATASET_MARKER = 0x44415441
DATASET_MAGIC = 0x53455455
def read_data(path):
infile = QtCore.QFile(path)
if not infile.open(QtCore.QIODevice.ReadOnly):
raise IOError(infile.errorString())
stream = QtCore.QDataStream(infile)
magic = stream.readUInt32()
if magic != MAGIC_NUMBER:
raise IOError('invalid magic number')
version = stream.readUInt32()
if version != FILE_VERSION:
raise IOError('invalid file version')
marker = stream.readUInt32()
if marker != DATASET_MARKER:
raise IOError('invalid dataset marker')
count = stream.readInt32()
if count < 1:
raise IOError('invalid dataset count')
stream.setVersion(QtCore.QDataStream.Qt_4_7)
rows = []
while not stream.atEnd():
row = []
magic = stream.readUInt32()
if magic != DATASET_MAGIC:
raise IOError('invalid dataset magic number')
row.append(('Name', stream.readQString()))
flags = stream.readUInt32()
row.append(('Flags', flags))
if flags & FLAG_HASID:
row.append(('ID', stream.readQString()))
if flags & FLAG_HASCOLOR:
color = QtGui.QColor()
stream >> color
row.append(('Color', color))
if flags & FLAG_HASUNITS:
row.append(('Units', stream.readInt32()))
if flags & FLAG_HASCREATORIDS:
row.append(('Creators', stream.readQStringList()))
if flags & FLAG_HASHIDDEN:
row.append(('Hidden', stream.readBool()))
if flags & FLAG_HASTHRESHOLDS:
thresholds = []
length = stream.readUInt32()
for index in range(length):
thresholds.append(stream.readDouble())
row.append(('Thresholds', thresholds))
if flags & FLAG_HASSOURCE:
row.append(('Source', stream.readQString()))
if flags & FLAG_HASROLE:
row.append(('Role', stream.readInt32()))
points = []
length = stream.readUInt32()
for index in range(length):
point = QtCore.QPointF()
stream >> point
points.append(point)
row.append(('Points', points))
rows.append(row)
infile.close()
return rows
rows = read_data('datasets.bin')
for index, row in enumerate(rows):
print('Row %s:' % index)
for key, data in row:
if isinstance(data, list) and len(data):
print(' %s = [%s ... ] (%s items)' % (
key, repr(data[:3])[1:-1], len(data)))
else:
print(' %s = %s' % (key, data))
