python - 在 PyQt5 中的 QTreeWidget 和 QListWidget 之间拖动项目？

Question

我有一个 QListWidget 和一个 QTreeWidget，我希望能够在每个列表项内以及它们之间拖动一个或多个列表项。我可以使用内部拖放功能，但我不确定如何在它们之间拖动。

当我在下面的代码中打印 event.mimeData().formats() 时，它会显示 ['application/x-qabstractitemmodeldatalist']。我被困在如何提取该项目的文本和索引(它应该是 QListWidgetItem 或 QTreeWidgetItem，对吧？)，以便我可以从源小部件中删除原始项目并将新项目添加到目标小部件中，我该怎么做那？

我尝试使用这里的代码:
https://wiki.python.org/moin/PyQt/Handling%20Qt%27s%20internal%20item%20MIME%20type

目前，当我在小部件之间拖动项目时，我的代码会获取 QVariant 项目，但我仍然不知道如何处理这些项目来获取项目文本和索引。

from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QTreeWidgetItem
import sys

class Tree(QtWidgets.QTreeWidget):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.setDragDropMode(self.DragDrop)
        self.setSelectionMode(self.ExtendedSelection)
        self.setAcceptDrops(True)

        for text in ['tree1','tree2','tree3']:
            treeItem = QtWidgets.QTreeWidgetItem(self, [text])
            treeItem.setFlags(treeItem.flags() & ~QtCore.Qt.ItemIsDropEnabled)
            self.addTopLevelItem(treeItem)

    def dropEvent(self, event):
        if event.source() == self:
            event.setDropAction(QtCore.Qt.MoveAction)
            super().dropEvent(event)
        elif isinstance(event.source(), QtWidgets.QListWidget):
            item = self.itemAt(event.pos())
            ix = self.indexAt(event.pos())
            col = 0 if item is None else ix.column()
            item = self.invisibleRootItem() if item is None else item
            ba = event.mimeData().data('application/x-qabstractitemmodeldatalist')
            data_items = decode_data(ba)
            for data_item in data_items:
                it = QtWidgets.QTreeWidgetItem()
                item.addChild(it)
                for data in data_items:
                    for r, v in data.items():
                        it.setData(col, r, v)


class List(QtWidgets.QListWidget):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.setDragDropMode(self.DragDrop)
        self.setSelectionMode(self.ExtendedSelection)
        self.setAcceptDrops(True)

        for text in ['list1','list2','list3']:
            self.addItem(text)

    def dropEvent(self, event):
        if event.source() == self:
            event.setDropAction(QtCore.Qt.MoveAction)
            QtWidgets.QListWidget.dropEvent(self, event)
        elif isinstance(event.source(), QtWidgets.QTreeWidget):
            item = self.itemAt(event.pos())
            row = self.row(item) if item else self.count()
            ba = event.mimeData().data('application/x-qabstractitemmodeldatalist')
            data_items = decode_data(ba)
            for i, data_item in enumerate(data_items):
                it = QtWidgets.QListWidgetItem()
                self.insertItem(row+i, it)
                for r, v in data_item.items():
                    it.setData(r,v)


def decode_data(bytearray):

    data = []
    item = {}

    ds = QtCore.QDataStream(bytearray)
    while not ds.atEnd():

        row = ds.readInt32()
        column = ds.readInt32()

        map_items = ds.readInt32()
        for i in range(map_items):
            key = ds.readInt32()

            value = QtCore.QVariant()
            ds >> value
            item[Qt.ItemDataRole(key)] = value

        data.append(item)
    return data

if __name__=='__main__':

    app = QtWidgets.QApplication(sys.argv)

    layout = QtWidgets.QHBoxLayout()
    layout.addWidget(Tree())
    layout.addWidget(List())

    container = QtWidgets.QWidget()
    container.setLayout(layout)
    container.show()

    app.exec_()

Answer 1

您必须使用decode_data返回的信息创建项目，这些信息是拖动的每个项目的角色和值:

class Tree(QtWidgets.QTreeWidget):
    # ...

    def dropEvent(self, event):
        if event.source() == self:
            event.setDropAction(QtCore.Qt.MoveAction)
            super().dropEvent(event)
        elif isinstance(event.source(), QtWidgets.QListWidget):
            item = self.itemAt(event.pos())
            ix = self.indexAt(event.pos())
            col = 0 if item is None else ix.column()
            item = self.invisibleRootItem() if item is None else item            
            ba = event.mimeData().data('application/x-qabstractitemmodeldatalist')
            data_items = decode_data(ba)
            for data_item in data_items:
                it = QtWidgets.QTreeWidgetItem()
                item.addChild(it)
                for data in data_items:
                    for r, v in data.items():
                        it.setData(col, r, v)

class List(QtWidgets.QListWidget):
    # ... 

    def dropEvent(self, event):
        if event.source() == self:
            event.setDropAction(QtCore.Qt.MoveAction)
            QtWidgets.QListWidget.dropEvent(self, event)
        elif isinstance(event.source(), QtWidgets.QTreeWidget):
            item = self.itemAt(event.pos())
            row = self.row(item) if item else self.count()
            ba = event.mimeData().data('application/x-qabstractitemmodeldatalist')
            data_items = decode_data(ba)
            for i, data_item in enumerate(data_items):
                it = QtWidgets.QListWidgetItem()
                self.insertItem(row+i, it)
                for r, v in data_item.items():
                    it.setData(r,v)