from PyQt5.QtWidgets import QComboBox
from PyQt5.QtCore import Qt


class CheckableComboBox(QComboBox):
    def __init__(self):
        super().__init__()
        self._changed = False
        self.view().pressed.connect(self.handleItemPressed)

    def setItemChecked(self, index, checked=False):
        item = self.model().item(index, self.modelColumn()) # QStandardItem object
        if checked:
            item.setCheckState(Qt.Checked)
        else:
            item.setCheckState(Qt.Unchecked)

    def handleItemPressed(self, index):
        item = self.model().itemFromIndex(index)
        if item.checkState() == Qt.Checked:
            item.setCheckState(Qt.Unchecked)
        else:
            item.setCheckState(Qt.Checked)
        self._changed = True

    def hidePopup(self):
        if not self._changed:
            super().hidePopup()
        self._changed = False

    def itemChecked(self, index):
        item = self.model().item(index, self.modelColumn())
        return item.checkState() == Qt.Checked