如何使用自定义dropEvent编码禁用拖放时的QTreeWidget插入？

Question

I have the following code and i want disable drag and drop in between QTreeWidgetItem existing in the tree. I can not figure out how? Any thoughts?

def dropEvent(self, event):
    target_item = self.itemAt(event.pos())
    if not target_item:
        return

    selected_items = self.selectedItems()
    item = None
    if selected_items:
        for item in selected_items:
            item_data = item.data(0, QtCore.Qt.UserRole)
            target_item_data = target_item.data(0, QtCore.Qt.UserRole)

            if components_api.is_plug(item.text(0)):
                if components_api.is_plug(target_item.text(0)):
                    return
            else:
                if not components_api.is_plug(item.text(0)):
                    if not components_api.is_part_root(item.text(0)):
                        return
                if not components_api.is_plug(target_item.text(0)):
                    return
            item.setExpanded(True)
    super(TreeWidget, self).dropEvent(event)

Answer 1

In simple cases, if no special implementation has been made, this should suffice:

class TreeWidget(QtWidgets.QTreeWidget):
    def __init__(self, parent=None):
        super(TreeWidget, self).__init__(parent)
        # ...
        self.setDragDropOverwriteMode(True)
        self.setDragDropMode(self.InternalMove)

Otherwise, you just can ignore the event if the drop indicator is not on the item, after processing the dragMove event using the base class implementation. Since the drop indicator should be shown to ensure a successful drag/drop operation and you probably don't want it visible if the operation should be ignored, you can enable it before calling the base implementation and then disable it afterwards accordingly:

    def dragMoveEvent(self, event):
        self.setDropIndicatorShown(True)
        super(TreeWidget, self).dragMoveEvent(event)
        if self.dropIndicatorPosition() != self.OnItem:
            self.setDropIndicatorShown(False)
            event.ignore()