Question

我试图在用户按下按钮时将节点移动到其父节点内。我拍了一张儿童快照，给它们重新排序，然后将它们全部加回来。但是，最初选择的节点永远不会被takeChild（）方法删除，所以我最终在父节点中有3个节点而不是两个节点。通过选择B类节点，然后选择“移动节点”，尝试下面的示例。按钮。基本的树代码是从另一个qq中获取的，并引用了下面的代号。

import sys
from PyQt4 import QtCore, QtGui
from PyQt4.QtCore import Qt

#see http://stackoverflow.com/questions/12737721/developing-pyqt4-tree-widget/13563375#13563375
class Window(QtGui.QWidget):

    def __init__(self):
        QtGui.QWidget.__init__(self)
        self.treeWidget = QtGui.QTreeWidget()
        self.treeWidget.setHeaderHidden(True)
        self.addItems(self.treeWidget.invisibleRootItem())
        self.treeWidget.itemChanged.connect (self.handleChanged)
        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.treeWidget)
        self.upPushButton = QtGui.QPushButton("Move node up")
        layout.addWidget(self.upPushButton)
        self.setLayout(layout)
        self.connectSlot()

    def addItems(self, parent):
        column = 0
        clients_item = self.addParent(parent, column, 'Clients', 'data Clients')
        vendors_item = self.addParent(parent, column, 'Vendors', 'data Vendors')
        time_period_item = self.addParent(parent, column, 'Time Period', 'data Time Period')

        self.addChild(clients_item, column, 'Type A', 'data Type A')
        self.addChild(clients_item, column, 'Type B', 'data Type B')

        self.addChild(vendors_item, column, 'Mary', 'data Mary')
        self.addChild(vendors_item, column, 'Arnold', 'data Arnold')

        self.addChild(time_period_item, column, 'Init', 'data Init')
        self.addChild(time_period_item, column, 'End', 'data End')

    def addParent(self, parent, column, title, data):
        item = QtGui.QTreeWidgetItem(parent, [title])
        item.setData(column, QtCore.Qt.UserRole, data)
        item.setChildIndicatorPolicy(QtGui.QTreeWidgetItem.ShowIndicator)
        item.setExpanded (True)
        return item

    def addChild(self, parent, column, title, data):
        item = QtGui.QTreeWidgetItem(parent, [title])
        item.setData(column, QtCore.Qt.UserRole, data)
        item.setCheckState (column, QtCore.Qt.Unchecked)
        return item

    def handleChanged(self, item, column):
        if item.checkState(column) == QtCore.Qt.Checked:
            print ("checked", item, item.text(column))
        if item.checkState(column) == QtCore.Qt.Unchecked:
            print ("unchecked", item, item.text(column))

    def upPushButtonClicked(self):
        '''Moves order within parent'''
        selectedTreeItems = self.treeWidget.selectedItems()
        if selectedTreeItems and len(selectedTreeItems) == 1:
            item = selectedTreeItems[0]
            itemData =  item.data(0, Qt.UserRole)
            parent = item.parent()

            #get children
            location = 0
            siblings = []
            if parent.childCount()>1:
                for i in range(parent.childCount()):
                    sibling = parent.child(i)
                    if sibling == item:
                        location = i
                    siblings.append(sibling)

            #switch position
            a, b = siblings.index(parent.child(location-1)), siblings.index(parent.child(location))
            siblings[b], siblings[a] = siblings[a], siblings[b]

            #clear the branch
            for j in range(parent.childCount()): 
                #This runs but the child is not removed when j == childCount-1
                parent.takeChild(j)

            #add all children back
            for node in siblings:
                self.addChild(parent, 0, node.text(0), node.data(0,     Qt.UserRole))            
    def connectSlot(self):
        self.upPushButton.clicked.connect(self.upPushButtonClicked)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())

Answer 1

出现问题是因为一旦删除了索引为0（第一次迭代时为parent.takechild(j)）的项目，那么唯一剩下的项目现在是索引0.但是下一次迭代尝试删除子项目索引1，现在还不存在！

简而言之，当您修改树视图（在这种情况下通过删除项目）时，用于跟踪树视图中的位置的任何索引都将变得毫无意义。

您可以使用parent.takeChildren()一次删除所有项目，或使用for j in range(parent.childCount()-1,-1,-1)向后遍历列表来解决您的具体问题。

请注意，在使用treeview执行其他操作时，应记住此类问题。您必须仔细考虑更改树视图将如何影响您用于访问树视图的任何整数！

在PyQt QTreeWidget中移动节点位置

1 个答案: