I want to pickle QPixmap object dict in Python 3
For example,
ImageQpixmapDict = {}
ImageQpixmapDict['XXX'] = QPixmap()
In this situation, I want to pickle ImageQpixmapDict variable
like
pickle.dump(ImageQpixmapDict, 'filePath')
I tried to pickle QPixmap object by using QSettings, but it doesn't work.
But as you know, QPixmap object couldn't be pickled. So, How can I solve this problem.
Only some Qt classes are pickable (see the docs) and among them there is no QPixmap so a solution is to create a derived class that implements that logic:
import pickle
from PyQt5 import QtCore, QtGui
class Pickable_QPixmap(QtGui.QPixmap):
def __reduce__(self):
return type(self), (), self.__getstate__()
def __getstate__(self):
ba = QtCore.QByteArray()
stream = QtCore.QDataStream(ba, QtCore.QIODevice.WriteOnly)
stream << self
return ba
def __setstate__(self, ba):
stream = QtCore.QDataStream(ba, QtCore.QIODevice.ReadOnly)
stream >> self
if __name__ == "__main__":
import sys
app = QtGui.QGuiApplication(sys.argv)
# create QPixmap
pixmap = QtGui.QPixmap(100, 100)
pixmap.fill(QtGui.QColor("red"))
with open("data.pickle", "wb") as f:
image_dict = dict()
image_dict["XXX"] = Pickable_QPixmap(
pixmap
) # convert QPixmap to Pickable_QPixmap
pickle.dump(image_dict, f)
with open("data.pickle", "rb") as f:
image_dict = pickle.load(f)
pixmap = image_dict["XXX"]
qpixmap = QtGui.QPixmap(pixmap) # convert Pickable_QPixmap to QPixmap
assert qpixmap.size() == pixmap.size() == QtCore.QSize(100, 100)
assert qpixmap.toImage() == pixmap.toImage()