如何阻止QTreeWidget在拖放时创建项目重复项

Question

以下代码会创建包含五个项目的QTreeWidget。 self.setDragDropMode(self.InternalMove)标志确保当项目被拖动时 另一个将没有它的副本（所以项目的数量始终保持不变）。

如果我们用self.setDragDropMode(self.DragDrop)替换此行，则每次拖放项目时都会创建一个新副本。

由于我不希望在每个dragAndDrop事件上创建项目的副本，所以如果它不会阻止InternalMove阻止QTreeWidget接受来自外部的丢弃，我会对InternalMove标志感到满意。它自己的视图（如果设置QTreeWidget标志QTreeWidget不允许从另一个QTreeWidget，QListView或文件浏览器中拖放。）
有没有办法设置覆盖，因此from PyQt4 import QtCore, QtGui app = QtGui.QApplication([]) class Tree(QtGui.QTreeWidget): def __init__(self, *args, **kwargs): super(Tree, self).__init__() self.setDragEnabled(True) self.setDropIndicatorShown(True) self.setDragDropMode(self.InternalMove) items=[QtGui.QTreeWidgetItem([name]) for name in ['Item_1','Item_2','Item_3','Item_4','Item_5']] self.addTopLevelItems(items) self.resize(360,240) self.show() tree=Tree() sys.exit(app.exec_()) 不会创建拖动项目的副本，但允许从其自己的窗口外部删除。

{{1}}

Answer 1

解决此问题的关键是您必须在对象移动到下一个QListsWidget时实施，并检查数据是否重复。通过删除源并将此数据添加到目标QListsWidget来获取源到目标的数据。

使用两种方法dragEnterEvent和dropEvent来处理所有这些方法;

1. 已实施dragEnterEvent检查要移动的对象是QListsWidget。

2. 已实施dropEvent检查数据是否重复并将数据从源传送到目的地。

示例：

import sys
from PyQt4 import QtCore, QtGui

class QCustomTreeWidget (QtGui.QTreeWidget):
    def __init__(self, parent = None):
        super(QCustomTreeWidget, self).__init__(parent)
        self.setDragEnabled(True)
        self.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
        self.resize(360,240)

    def dragEnterEvent (self, eventQDragEnterEvent):
        sourceQCustomTreeWidget = eventQDragEnterEvent.source()
        if isinstance(sourceQCustomTreeWidget, QCustomTreeWidget):
            if self != sourceQCustomTreeWidget:
                sourceQCustomTreeWidget.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
                eventQDragEnterEvent.accept()
            else:
                sourceQCustomTreeWidget.setDragDropMode(QtGui.QAbstractItemView.InternalMove)
                QtGui.QTreeWidget.dragEnterEvent(self, eventQDragEnterEvent)
        else:
            QtGui.QTreeWidget.dragEnterEvent(self, eventQDragEnterEvent)

    def dropEvent (self, eventQDropEvent):
        sourceQCustomTreeWidget = eventQDropEvent.source()
        if isinstance(sourceQCustomTreeWidget, QCustomTreeWidget):
            if self != sourceQCustomTreeWidget:
                sourceQCustomTreeWidget.setDragDropMode(QtGui.QAbstractItemView.DragDrop)
                sourceQTreeWidgetItem = sourceQCustomTreeWidget.currentItem()
                isFound = False
                for column in range(0, self.columnCount()):
                    sourceQString = sourceQTreeWidgetItem.text(column)
                    listsFoundQTreeWidgetItem = self.findItems(sourceQString, QtCore.Qt.MatchExactly, column)
                    if listsFoundQTreeWidgetItem:
                        isFound = True
                        break
                if not isFound:
                    (sourceQTreeWidgetItem.parent() or sourceQCustomTreeWidget.invisibleRootItem()).removeChild(sourceQTreeWidgetItem)
                    self.invisibleRootItem().addChild(sourceQTreeWidgetItem)
            else:
                sourceQCustomTreeWidget.setDragDropMode(QtGui.QAbstractItemView.InternalMove)
                QtGui.QTreeWidget.dropEvent(self, eventQDropEvent)
        else:
            QtGui.QTreeWidget.dropEvent(self, eventQDropEvent)

class QCustomQWidget (QtGui.QWidget):
    def __init__ (self, parent = None):
        super(QCustomQWidget, self).__init__(parent)
        self.my1QCustomTreeWidget = QCustomTreeWidget(self)
        self.my2QCustomTreeWidget = QCustomTreeWidget(self)
        items = [QtGui.QTreeWidgetItem([name]) for name in ['Item_1', 'Item_2', 'Item_3', 'Item_4', 'Item_5']]
        self.my1QCustomTreeWidget.addTopLevelItems(items)
        self.allQHBoxLayout = QtGui.QHBoxLayout()
        self.allQHBoxLayout.addWidget(self.my1QCustomTreeWidget)
        self.allQHBoxLayout.addWidget(self.my2QCustomTreeWidget)
        self.setLayout(self.allQHBoxLayout)

app = QtGui.QApplication([])
myQCustomQWidget = QCustomQWidget()
myQCustomQWidget.show()
sys.exit(app.exec_())

Useful reference for event handle