如何腌制QPixmap？

Question

我有一个存储要生成的QPixmap的类。我想对它进行分类，这样它就可以从一个会话重用到下一个会话，而不需要从初始图像重新计算(有一些调整大小和繁重的操作)。

QPixmap是不可选择的，所以它不能工作，但我注意到QByteArray是可选择的。因此，我尝试实现一个'getstate'，'setstate‘解决方案。见下文。

class StoreQPixmap:

    def __init__(self):
        # store QPixmap computed image - It is a dictionary as several images can 
         be stored for the same picture and
        # the dictionary key is the way to distinguish them
        self._qpixmap = {}


    def set_qpixmap(self, hash_, qpixmap):
        self._qpixmap[hash_] = qpixmap

    def get_qpixmap(self, hash_):
        try:
            return self._qpixmap[hash_]
        except KeyError:
            return None

    def del_qpixmap(self, hash_):
        try:
            del self._qpixmap[hash_]
            return True
        except KeyError:
            return False

    def __getstate__(self):
        # QPixmap is not pickable so let's transform it into QByteArray that does support pickle
        state = []
        qbyte_array = QByteArray()
        buffer = QBuffer(qbyte_array)
        for key, value in self._qpixmap.items():
            buffer.open(QIODevice.WriteOnly)
            value.save(buffer, 'PNG')
            state.append((key,buffer))
        return state

    def __setstate__(self, state):
        # retrieve a QByteArray and transform it into QPixmap
        qpixmap = QPixmap()
        for key, buffer in state:
            qpixmap.loadFromData(buffer)
            self._qpixmap[key] = qpixmap

但是为了将QPixmap翻译成QByteArray，我似乎需要一个QBuffer..that是不可选的，我回到了最初的问题:-(

有谁能告诉我通过将对象转换为“可选择的东西”来实现Q像素映射泡菜的方法？

谢谢

Answer 1

使用下面的QDatastream更新代码

class StoreQPixmap:

def __init__(self):
    # store QPixmap computed image - It is a dictionary as several images can be stored for the same picture and
    # the dictionary key is the way to distinguish them
    self._qpixmap = {}

   def __getstate__(self):
    # QPixmap is not pickable so let's transform it into QByteArray that does support pickle
    state = []
    for key, value in self._qpixmap.items():
        qbyte_array = QByteArray()
        stream = QDataStream(qbyte_array, QIODevice.WriteOnly)
        stream << value
        state.append((key, qbyte_array))
    return state

def __setstate__(self, state):

    self._qpixmap = {}
    # retrieve a QByteArray and transform it into QPixmap
    for (key, buffer) in state:
        qpixmap = QPixmap()
        stream = QDataStream(buffer, QIODevice.ReadOnly)
        stream >> qpixmap
        self._qpixmap[key] = qpixmap