Question

使用identical question asked about QListWidgets作为指南，我正在尝试制作一个QStandardItemModel，我可以在其中撤消项目的编辑。

从下面的SSCCE中可以看出，我几乎完全复制了这个示例，但稍微进行了一些调整，因为currentItemChanged QStandardItemModel不可用。为了解决这个问题，我使用clicked信号来修复项目的上一个文本。

奇怪的是，正确的描述显示在undostack中，但当我点击undo按钮时，它实际上没有撤消任何内容。

请注意，目前的问题表面上与this question相同。在其他版本中接受的答案不是一个答案，而是一个暗示。这是我试图在这里实施的提示，但它还没有工作。由于这个问题更具体和详细，因此不应视为重复，IMO。

SSCCE

from PySide import QtGui, QtCore
import sys

class CommandItemEdit(QtGui.QUndoCommand):
    def __init__(self, model, item, textBeforeEdit, description = "Item edited"):
        QtGui.QUndoCommand.__init__(self, description)
        self.model = model
        self.item = item
        self.textBeforeEdit = textBeforeEdit
        self.textAfterEdit = item.text()

    def redo(self):
        self.model.blockSignals(True)  
        self.item.setText(self.textAfterEdit)
        self.model.blockSignals(False)

    def undo(self):
        self.model.blockSignals(True)
        self.item.setText(self.textBeforeEdit)
        self.model.blockSignals(False)     


class UndoableTree(QtGui.QWidget):
    def __init__(self, parent = None):
        QtGui.QWidget.__init__(self, parent = None)
        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.view = QtGui.QTreeView()
        self.model = self.createModel()
        self.view.setModel(self.model)
        self.view.expandAll()
        self.undoStack = QtGui.QUndoStack(self)
        undoView = QtGui.QUndoView(self.undoStack)
        buttonLayout = self.buttonSetup()
        mainLayout = QtGui.QHBoxLayout(self)
        mainLayout.addWidget(undoView)
        mainLayout.addWidget(self.view)
        mainLayout.addLayout(buttonLayout)
        self.setLayout(mainLayout)
        self.makeConnections()
        #For undo/redo editing
        self.textBeforeEdit = ""

    def makeConnections(self):
        self.view.clicked.connect(self.itemClicked)
        self.model.itemChanged.connect(self.itemChanged)
        self.quitButton.clicked.connect(self.close)
        self.undoButton.clicked.connect(self.undoStack.undo)
        self.redoButton.clicked.connect(self.undoStack.redo)

    def itemClicked(self, index):
        item = self.model.itemFromIndex(index)
        self.textBeforeEdit = item.text()  

    def itemChanged(self, item):
        command = CommandItemEdit(self.model, item, self.textBeforeEdit, 
            "Renamed '{0}' to '{1}'".format(self.textBeforeEdit, item.text()))
        self.undoStack.push(command)


    def buttonSetup(self):
        self.undoButton = QtGui.QPushButton("Undo")
        self.redoButton = QtGui.QPushButton("Redo")
        self.quitButton = QtGui.QPushButton("Quit")
        buttonLayout = QtGui.QVBoxLayout()
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.undoButton)
        buttonLayout.addWidget(self.redoButton)
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.quitButton)
        return buttonLayout

    def createModel(self):
        model = QtGui.QStandardItemModel()
        model.setHorizontalHeaderLabels(['Titles', 'Summaries'])
        rootItem = model.invisibleRootItem()
        #First top-level row and children 
        item0 = [QtGui.QStandardItem('Title0'), QtGui.QStandardItem('Summary0')]
        item00 = [QtGui.QStandardItem('Title00'), QtGui.QStandardItem('Summary00')]
        item01 = [QtGui.QStandardItem('Title01'), QtGui.QStandardItem('Summary01')]
        rootItem.appendRow(item0)
        item0[0].appendRow(item00)
        item0[0].appendRow(item01)
        #Second top-level item and its children
        item1 = [QtGui.QStandardItem('Title1'), QtGui.QStandardItem('Summary1')]
        item10 = [QtGui.QStandardItem('Title10'), QtGui.QStandardItem('Summary10')]
        item11 = [QtGui.QStandardItem('Title11'), QtGui.QStandardItem('Summary11')]
        rootItem.appendRow(item1)
        item1[0].appendRow(item10)
        item1[0].appendRow(item11)

        return model


def main():
    app = QtGui.QApplication(sys.argv)
    newTree = UndoableTree()
    newTree.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

Answer 1

问题似乎出现，因为blockSignals()阻止了树视图被重新绘制。我认为这是因为当模型中的数据被修改时，模型会向树视图发出一个信号，当你调用model.blockSignals(True)时，这显然会被阻止。如果在单击撤消/重做后手动调整窗口大小（显然只有在有撤消/重做的东西时才有效），您会看到撤消/重做实际已应用，它只是没有最初显示它。

为了解决这个问题，我修改了代码，以便不断阻塞信号，而是断开相关信号并重新连接。这允许模型和树视图在撤消/重做正在进行时继续正确通信。

请参阅以下代码

from PySide import QtGui, QtCore
import sys

class CommandItemEdit(QtGui.QUndoCommand):
    def __init__(self, connectSignals, disconnectSignals, model, item, textBeforeEdit, description = "Item edited"):
        QtGui.QUndoCommand.__init__(self, description)
        self.model = model
        self.item = item
        self.textBeforeEdit = textBeforeEdit
        self.textAfterEdit = item.text()
        self.connectSignals = connectSignals
        self.disconnectSignals = disconnectSignals

    def redo(self):
        self.disconnectSignals()
        self.item.setText(self.textAfterEdit)
        self.connectSignals()

    def undo(self):
        self.disconnectSignals()
        self.item.setText(self.textBeforeEdit)
        self.connectSignals()


class UndoableTree(QtGui.QWidget):
    def __init__(self, parent = None):
        QtGui.QWidget.__init__(self, parent = None)
        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.view = QtGui.QTreeView()
        self.model = self.createModel()
        self.view.setModel(self.model)
        self.view.expandAll()
        self.undoStack = QtGui.QUndoStack(self)
        undoView = QtGui.QUndoView(self.undoStack)
        buttonLayout = self.buttonSetup()
        mainLayout = QtGui.QHBoxLayout(self)
        mainLayout.addWidget(undoView)
        mainLayout.addWidget(self.view)
        mainLayout.addLayout(buttonLayout)
        self.setLayout(mainLayout)
        self.makeConnections()
        #For undo/redo editing
        self.textBeforeEdit = ""

    def makeConnections(self):
        self.view.clicked.connect(self.itemClicked)
        self.model.itemChanged.connect(self.itemChanged)
        self.quitButton.clicked.connect(self.close)
        self.undoButton.clicked.connect(self.undoStack.undo)
        self.redoButton.clicked.connect(self.undoStack.redo)

    def disconnectSignal(self):    
        self.model.itemChanged.disconnect(self.itemChanged)

    def connectSignal(self):
        self.model.itemChanged.connect(self.itemChanged)

    def itemClicked(self, index):
        item = self.model.itemFromIndex(index)
        self.textBeforeEdit = item.text()  

    def itemChanged(self, item):
        command = CommandItemEdit(self.connectSignal, self.disconnectSignal, self.model, item, self.textBeforeEdit, 
            "Renamed '{0}' to '{1}'".format(self.textBeforeEdit, item.text()))
        self.undoStack.push(command)


    def buttonSetup(self):
        self.undoButton = QtGui.QPushButton("Undo")
        self.redoButton = QtGui.QPushButton("Redo")
        self.quitButton = QtGui.QPushButton("Quit")
        buttonLayout = QtGui.QVBoxLayout()
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.undoButton)
        buttonLayout.addWidget(self.redoButton)
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.quitButton)
        return buttonLayout

    def createModel(self):
        model = QtGui.QStandardItemModel()
        model.setHorizontalHeaderLabels(['Titles', 'Summaries'])
        rootItem = model.invisibleRootItem()
        #First top-level row and children 
        item0 = [QtGui.QStandardItem('Title0'), QtGui.QStandardItem('Summary0')]
        item00 = [QtGui.QStandardItem('Title00'), QtGui.QStandardItem('Summary00')]
        item01 = [QtGui.QStandardItem('Title01'), QtGui.QStandardItem('Summary01')]
        rootItem.appendRow(item0)
        item0[0].appendRow(item00)
        item0[0].appendRow(item01)
        #Second top-level item and its children
        item1 = [QtGui.QStandardItem('Title1'), QtGui.QStandardItem('Summary1')]
        item10 = [QtGui.QStandardItem('Title10'), QtGui.QStandardItem('Summary10')]
        item11 = [QtGui.QStandardItem('Title11'), QtGui.QStandardItem('Summary11')]
        rootItem.appendRow(item1)
        item1[0].appendRow(item10)
        item1[0].appendRow(item11)

        return model


def main():
    app = QtGui.QApplication(sys.argv)
    newTree = UndoableTree()
    newTree.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

其他信息

我发现如果您在取消阻止信号后明确调用CommandItemEdit，则可以使用self.model.layoutChanged.emit()的原始实现。这会强制树视图更新，而不会调用UndoableTree.itemChanged()插槽。

注意，树视图连接到模型信号，而树视图又连接到UndoableTree.itemChanged()插槽。

我也尝试发出dataChanged()信号，但这最终会调用仍连接的UndoableTree.itemChanged()插槽，从而导致无限递归。我认为这是调用model.blockSignals()的目标，所以不明确地调用它是有道理的！

所以最后，虽然这些附加方法中的一个确实有效，但我仍然会第一个明确断开信号的答案。这只是因为我认为最好让模型和树视图之间的通信保持完整，而不是在手动触发您仍想要的信号时限制某些通信。后一种方法可能会产生意想不到的副作用，并且很难调试。

Answer 2

致quote another answer一个密切相关的问题：

点击的信号似乎完全是错误的跟踪方式变化。你将如何处理通过键盘进行的更改？那么以编程方式进行的更改呢？撤消堆栈工作正常，每个更改都必须记录，并在与它的订单完全相同。

同一篇文章继续建议创建一个自定义信号，在实际更改数据时发出旧/新数据。最后，我使用了三个我从SO那里无耻地偷走的想法。首先，three_pineapples' insight需要disconnect来避免无限递归。其次，子类QStandardItemModel定义一个新的itemDataChanged信号，它将先前和新数据都发送到一个槽。第三，子类QStandardItem并在数据发生变化时发出此信号：这是在setData()）的重新实现中处理的。

以下是完整代码：

# -*- coding: utf-8 -*-

from PySide import QtGui, QtCore
import sys

class CommandTextEdit(QtGui.QUndoCommand):
    def __init__(self, tree, item, oldText, newText, description):
        QtGui.QUndoCommand.__init__(self, description)
        self.item = item
        self.tree = tree
        self.oldText = oldText
        self.newText = newText

    def redo(self):      
        self.item.model().itemDataChanged.disconnect(self.tree.itemDataChangedSlot) 
        self.item.setText(self.newText)
        self.item.model().itemDataChanged.connect(self.tree.itemDataChangedSlot) 

    def undo(self):
        self.item.model().itemDataChanged.disconnect(self.tree.itemDataChangedSlot) 
        self.item.setText(self.oldText)
        self.item.model().itemDataChanged.connect(self.tree.itemDataChangedSlot) 


class CommandCheckStateChange(QtGui.QUndoCommand):
    def __init__(self, tree, item, oldCheckState, newCheckState, description):
        QtGui.QUndoCommand.__init__(self, description)
        self.item = item
        self.tree = tree
        self.oldCheckState = QtCore.Qt.Unchecked if oldCheckState == 0 else QtCore.Qt.Checked
        self.newCheckState = QtCore.Qt.Checked if oldCheckState == 0 else QtCore.Qt.Unchecked

    def redo(self): #disoconnect to avoid recursive loop b/w signal-slot
        self.item.model().itemDataChanged.disconnect(self.tree.itemDataChangedSlot) 
        self.item.setCheckState(self.newCheckState)
        self.item.model().itemDataChanged.connect(self.tree.itemDataChangedSlot) 

    def undo(self):
        self.item.model().itemDataChanged.disconnect(self.tree.itemDataChangedSlot)
        self.item.setCheckState(self.oldCheckState)
        self.item.model().itemDataChanged.connect(self.tree.itemDataChangedSlot) 


class StandardItemModel(QtGui.QStandardItemModel):
    itemDataChanged = QtCore.Signal(object, object, object, object)


class StandardItem(QtGui.QStandardItem):
    def setData(self, newValue, role=QtCore.Qt.UserRole + 1):
        if role == QtCore.Qt.EditRole:
            oldValue = self.data(role)
            QtGui.QStandardItem.setData(self, newValue, role)
            model = self.model()
            #only emit signal if newvalue is different from old
            if model is not None and oldValue != newValue:
                model.itemDataChanged.emit(self, oldValue, newValue, role)
            return True
        if role == QtCore.Qt.CheckStateRole:
            oldValue = self.data(role)
            QtGui.QStandardItem.setData(self, newValue, role)
            model = self.model()
            if model is not None and oldValue != newValue:
                model.itemDataChanged.emit(self, oldValue, newValue, role)
            return True
        QtGui.QStandardItem.setData(self, newValue, role)


class UndoableTree(QtGui.QWidget):
    def __init__(self, parent = None):
        QtGui.QWidget.__init__(self, parent = None)
        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.view = QtGui.QTreeView()
        self.model = self.createModel()
        self.view.setModel(self.model)
        self.view.expandAll()
        self.undoStack = QtGui.QUndoStack(self)
        undoView = QtGui.QUndoView(self.undoStack)
        buttonLayout = self.buttonSetup()
        mainLayout = QtGui.QHBoxLayout(self)
        mainLayout.addWidget(undoView)
        mainLayout.addWidget(self.view)
        mainLayout.addLayout(buttonLayout)
        self.setLayout(mainLayout)
        self.makeConnections()

    def makeConnections(self):
        self.model.itemDataChanged.connect(self.itemDataChangedSlot)
        self.quitButton.clicked.connect(self.close)
        self.undoButton.clicked.connect(self.undoStack.undo)
        self.redoButton.clicked.connect(self.undoStack.redo)

    def itemDataChangedSlot(self, item, oldValue, newValue, role):
        if role == QtCore.Qt.EditRole:
            command = CommandTextEdit(self, item, oldValue, newValue,
                "Text changed from '{0}' to '{1}'".format(oldValue, newValue))
            self.undoStack.push(command)
            return True
        if role == QtCore.Qt.CheckStateRole:
            command = CommandCheckStateChange(self, item, oldValue, newValue, 
                "CheckState changed from '{0}' to '{1}'".format(oldValue, newValue))
            self.undoStack.push(command)
            return True

    def buttonSetup(self):
        self.undoButton = QtGui.QPushButton("Undo")
        self.redoButton = QtGui.QPushButton("Redo")
        self.quitButton = QtGui.QPushButton("Quit")
        buttonLayout = QtGui.QVBoxLayout()
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.undoButton)
        buttonLayout.addWidget(self.redoButton)
        buttonLayout.addStretch()
        buttonLayout.addWidget(self.quitButton)
        return buttonLayout

    def createModel(self):
        model = StandardItemModel()
        model.setHorizontalHeaderLabels(['Titles', 'Summaries'])
        rootItem = model.invisibleRootItem()
        item0 = [StandardItem('Title0'), StandardItem('Summary0')]
        item00 = [StandardItem('Title00'), StandardItem('Summary00')]
        item01 = [StandardItem('Title01'), StandardItem('Summary01')]
        item0[0].setCheckable(True)
        item00[0].setCheckable(True)
        item01[0].setCheckable(True)
        rootItem.appendRow(item0)
        item0[0].appendRow(item00)
        item0[0].appendRow(item01)
        return model


def main():
    app = QtGui.QApplication(sys.argv)
    newTree = UndoableTree()
    newTree.show()
    sys.exit(app.exec_())    

if __name__ == "__main__":
    main()

总的来说，这似乎比使用clicked更好。

如何在PySide / PyQt中撤消QStandardItem的编辑？

2 个答案:

其他信息