qt: pyqt: QTreeView 内部拖放几乎可以正常工作...被拖动的项目消失了
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【中文标题】qt: pyqt: QTreeView 内部拖放几乎可以正常工作...被拖动的项目消失了【英文标题】：qt: pyqt: QTreeView internal drag and drop almost working... dragged item disappears 【发布时间】：2011-05-14 05:16:29 【问题描述】：我几乎在 QTreeView 中有一个完全正常的拖放重新排序。一切似乎都很好，除了丢弃的对象从未出现（尽管我可以引用它许多不同的方式，向我证明它确实存在于它应该存在的地方）。如果有人有时间并且可以运行以下代码并让我知道我做错了什么，我将不胜感激。一个多星期以来，我一直在反对这个过程：
您应该能够只复制并运行以下代码（我在其中有一堆打印语句，似乎表明一切正常，但显然有些问题）：
import sys
from PyQt4 import QtGui
from PyQt4 import QtCore
################################################################################
class Branch(object):
"""
Basic branch/leaf node.
"""
#---------------------------------------------------------------------------
def __init__(self, name, value, parent=None):
"""
Constructor.
"""
super(Branch, self).__init__()
#name and parent are both to be stored directly as variables
self.name = name
self.parent = parent
self.value = value
#store sub-objects (usually other branches)
self.objD = dict()
self.nameL = list()
#---------------------------------------------------------------------------
def get_name(self):
"""
Getter.
"""
return self.name
#---------------------------------------------------------------------------
def get_parent(self):
"""
Returns the parent of this object.
"""
return self.parent
#---------------------------------------------------------------------------
def set_value(self, value):
"""
Generic setter for all settings.
"""
self.value = value
#---------------------------------------------------------------------------
def get_value(self):
"""
Generic getter for all settings. Returns the display value
"""
return self.value
#---------------------------------------------------------------------------
def add_child_obj(self, obj, row=None):
"""
Adds the param object to the dict and list.
"""
self.objD[obj.get_name()] = obj
if row == None:
self.nameL.append(obj.get_name())
else:
self.nameL.insert(row, obj.get_name())
print "JUST ADDED CHILD AT ROW:", self.nameL.index(obj.get_name())
#---------------------------------------------------------------------------
def remove_child_at_row(self, row):
"""
Removes the param object from the dict and list.
"""
childName = self.nameL[row]
del(self.nameL[row])
del(self.objD[childName])
#---------------------------------------------------------------------------
def get_child_count(self):
"""
Returns the number of children in this branch.
"""
return len(self.nameL)
#---------------------------------------------------------------------------
def get_child_list(self):
"""
Returns a list of the visible children names.
"""
return self.nameL
#---------------------------------------------------------------------------
def get_child_at_row(self, row):
"""
Returns a specific child object based on its ordinal (only consider
visible children).
"""
childName = self.nameL[row]
return self.objD[childName]
#---------------------------------------------------------------------------
def get_child_by_name(self, childName):
"""
Returns a specific child object based on its name.
"""
return self.objD[childName]
#---------------------------------------------------------------------------
def get_index(self):
"""
Returns this object's index position with regard to its siblings.
"""
siblingsL = self.parent.get_child_list()
return siblingsL.index(self.get_name())
################################################################################
class MyTreeView(QtGui.QTreeView):
"""
Overrides the QTreeView to handle keypress events.
"""
#---------------------------------------------------------------------------
def __init__(self, model, parent=None):
"""
Constructor for the TreeView class.
"""
super(MyTreeView, self).__init__(parent)
self.setModel(model)
################################################################################
class MyTreeModel(QtCore.QAbstractItemModel):
"""
My tree view data model
"""
#---------------------------------------------------------------------------
def __init__(self, root):
"""
Constructor for the TreeModel class
"""
super(MyTreeModel, self).__init__()
self.root = root
self.fontSize = 8
self.selection = None
#---------------------------------------------------------------------------
def columnCount(self, index=QtCore.QModelIndex()):
"""
Returns the number of columns in the treeview.
"""
return 1
#---------------------------------------------------------------------------
def rowCount(self, index=QtCore.QModelIndex()):
"""
Returns the number of children of the current index obj.
"""
if index.column() > 0:
return 0
if not index.isValid():
item = self.root
else:
item = index.internalPointer()
if item:
return item.get_child_count()
return 0
#---------------------------------------------------------------------------
def index(self, row, column, parent):
"""
Returns a QModelIndex item for the current row, column, and parent.
"""
if not self.hasIndex(row, column, parent):
return QtCore.QModelIndex()
if not parent.isValid():
parentItem = self.root
else:
parentItem = parent.internalPointer()
childItem = parentItem.get_child_at_row(row)
if childItem:
return self.createIndex(row, column, childItem)
else:
return QtCore.QModelIndex()
#---------------------------------------------------------------------------
def parent(self, index):
"""
Returns a QModelIndex item for the parent of the given index.
"""
if not index.isValid():
return QtCore.QModelIndex()
childItem = index.internalPointer()
if not childItem:
return QtCore.QModelIndex()
parentItem = childItem.get_parent()
if parentItem == self.root:
return QtCore.QModelIndex()
return self.createIndex(parentItem.get_index(), 0, parentItem)
#---------------------------------------------------------------------------
def data(self, index, role=QtCore.Qt.DisplayRole):
"""
Returns the text or formatting for a particular cell, depending on the
role supplied.
"""
#invalid indexes return invalid results
if not index.isValid():
return QtCore.QVariant()
#access the underlying referenced object
item = index.internalPointer()
#edit role displays the raw values
if role == QtCore.Qt.EditRole:
return item.get_value()
#return the data to display
if role == QtCore.Qt.DisplayRole or role == QtCore.Qt.EditRole:
return item.get_value()
return QtCore.QVariant()
#---------------------------------------------------------------------------
def headerData(self, index, orientation, role=QtCore.Qt.DisplayRole):
"""
Returns the text for the horizontal headers (parameter names)
"""
if role == QtCore.Qt.TextAlignmentRole:
if orientation == QtCore.Qt.Horizontal:
alignment = int(QtCore.Qt.AlignLeft|QtCore.Qt.AlignVCenter)
return QtCore.QVariant(alignment)
alignment = int(QtCore.Qt.AlignLeft|QtCore.Qt.AlignVCenter)
return QtCore.QVariant(alignment)
if role != QtCore.Qt.DisplayRole:
return QtCore.QVariant()
if orientation == QtCore.Qt.Horizontal:
if int(index) == 0:
return "Name"
#---------------------------------------------------------------------------
def supportedDropActions(self):
"""
We allow re-ordering.
"""
return QtCore.Qt.MoveAction
#---------------------------------------------------------------------------
def flags(self, index):
"""
Returns whether or not the current item is editable/selectable/etc.
"""
if not index.isValid():
return QtCore.Qt.ItemIsEnabled
#by default, you can't do anything
enabled = QtCore.Qt.ItemIsEnabled
selectable = QtCore.Qt.ItemIsSelectable
editable = QtCore.Qt.ItemIsEditable
draggable = QtCore.Qt.ItemIsDragEnabled
droppable = QtCore.Qt.ItemIsDropEnabled
#return our flags.
return enabled | selectable| editable| draggable| droppable
#---------------------------------------------------------------------------
def setData(self, index, value, role=QtCore.Qt.EditRole):
"""
Sets the data.
"""
#convert the value into a string
if value:
item = index.internalPointer()
item.set_value(value)
self.emit(QtCore.SIGNAL("dataChanged(QModelIndex,QModelIndex)"),
index, index)
return True
#---------------------------------------------------------------------------
def supportedDropActions(self):
"""
Only allow moves
"""
return QtCore.Qt.MoveAction
#---------------------------------------------------------------------------
def mimeTypes(self):
"""
Only accept the internal custom drop type which is plain text
"""
types = QtCore.QStringList()
types.append('text/plain')
return types
#---------------------------------------------------------------------------
def mimeData(self, index):
"""
Wrap the index up as a list of rows and columns of each
parent/grandparent/etc
"""
rc = ""
theIndex = index[0] #<- for testing purposes we only deal with 1st item
while theIndex.isValid():
rc = rc + str(theIndex.row()) + ";" + str(theIndex.column())
theIndex = self.parent(theIndex)
if theIndex.isValid():
rc = rc + ","
mimeData = QtCore.QMimeData()
mimeData.setText(rc)
return mimeData
#---------------------------------------------------------------------------
def dropMimeData(self, data, action, row, column, parentIndex):
"""
Extract the whole ancestor list of rows and columns and rebuild the
index item that was originally dragged
"""
if action == QtCore.Qt.IgnoreAction:
return True
if data.hasText():
ancestorL = str(data.text()).split(",")
ancestorL.reverse() #<- stored from the child up, we read from ancestor down
pIndex = QtCore.QModelIndex()
for ancestor in ancestorL:
srcRow = int(ancestor.split(";")[0])
srcCol = int(ancestor.split(";")[1])
itemIndex = self.index(srcRow, srcCol, pIndex)
pIndex = itemIndex
item = itemIndex.internalPointer()
parent = parentIndex.internalPointer()
#modify the row if it is -1 (we want to append to the end of the list)
if row == -1:
row = parent.get_child_count()
self.beginInsertRows(parentIndex, row-1, row)
print "------------------"
parentIndex.internalPointer().add_child_obj(item)
print "------------------"
self.endInsertRows()
print "sanity check:"
print "dragged Node", item.get_name()
print "parent Node", parent.get_name()
print "inserted at row",row
print "inserted Node:",parent.get_child_at_row(row).get_name()
print row, column
print "from index():",self.index(row, 0, parentIndex).internalPointer().get_name()
self.emit(QtCore.SIGNAL("dataChanged(QModelIndex,QModelIndex)"),
self.index(row, 0, parentIndex),
self.index(row, 0, parentIndex))
return True
#---------------------------------------------------------------------------
def insertRow(self, row, parent):
print "insertRow"
return self.insertRows(row, 1, parent)
#---------------------------------------------------------------------------
def insertRows(self, row, count, parent):
print "insertRows"
self.beginInsertRows(parent, row, (row + (count - 1)))
self.endInsertRows()
return True
#---------------------------------------------------------------------------
def removeRow(self, row, parentIndex):
print "removeRow"
return self.removeRows(row, 1, parentIndex)
#---------------------------------------------------------------------------
def removeRows(self, row, count, parentIndex):
self.beginRemoveRows(parentIndex, row, row)
print "about to remove child at row:",row
print "which is under the parent named:",parentIndex.internalPointer().get_name()
print "and whose own name is:",parentIndex.internalPointer().get_child_at_row(row).get_name()
parentIndex.internalPointer().remove_child_at_row(row)
self.endRemoveRows()
return True
class Ui_MainWindow(object):
def printChildren(self, item):
print item.name
for child in item.get_child_list():
self.printChildren(item.get_child_by_name(child))
def printit(self):
self.printChildren(self.root)
def setupUi(self, MainWindow):
root = Branch("root", "root", QtCore.QVariant)
item1 = Branch("ITEM1","ITEM1",root)
item2 = Branch("ITEM2","ITEM2",root)
item3 = Branch("ITEM3","ITEM3",root)
root.add_child_obj(item1)
root.add_child_obj(item2)
root.add_child_obj(item3)
item1a = Branch("thinga","thinga",item1)
item1b = Branch("thingb","thingb",item1)
item1.add_child_obj(item1a)
item1.add_child_obj(item1b)
item2a = Branch("thingc","thingc",item2)
item2b = Branch("thingd","thingd",item2)
item2.add_child_obj(item2a)
item2.add_child_obj(item2b)
item3a = Branch("thinge","thinge",item3)
item3b = Branch("thingf","thingf",item3)
item3.add_child_obj(item3a)
item3.add_child_obj(item3b)
item1a1 = Branch("___A","___A",item1a)
item1a2 = Branch("___B","___B",item1a)
item1a.add_child_obj(item1a1)
item1a.add_child_obj(item1a2)
item1b1 = Branch("___C","___C",item1b)
item1b2 = Branch("___D","___D",item1b)
item1b.add_child_obj(item1b1)
item1b.add_child_obj(item1b2)
item2a1 = Branch("___E","___E",item2a)
item2a2 = Branch("___F","___F",item2a)
item2a.add_child_obj(item2a1)
item2a.add_child_obj(item2a2)
item2b1 = Branch("___G","___G",item2b)
item2b2 = Branch("___H","___H",item2b)
item2b.add_child_obj(item2b1)
item2b.add_child_obj(item2b2)
item3a1 = Branch("___J","___J",item3a)
item3a2 = Branch("___K","___K",item3a)
item3a.add_child_obj(item3a1)
item3a.add_child_obj(item3a2)
item3b1 = Branch("___L","___L",item3b)
item3b2 = Branch("___M","___M",item3b)
item3b.add_child_obj(item3b1)
item3b.add_child_obj(item3b2)
self.root = root
MainWindow.setObjectName("MainWindow")
MainWindow.resize(600, 400)
self.centralwidget = QtGui.QWidget(MainWindow)
self.centralwidget.setObjectName("centralwidget")
self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget)
self.horizontalLayout.setObjectName("horizontalLayout")
self.myModel = MyTreeModel(root)
self.treeView = MyTreeView(self.myModel, self.centralwidget)
self.treeView.setObjectName("treeView")
self.treeView.dragEnabled()
self.treeView.acceptDrops()
self.treeView.showDropIndicator()
self.treeView.setDragDropMode(QtGui.QAbstractItemView.InternalMove)
self.treeView.expandAll()
self.horizontalLayout.addWidget(self.treeView)
self.btn = QtGui.QPushButton('print', MainWindow)
MainWindow.connect(self.btn, QtCore.SIGNAL("clicked()"), self.printit)
self.horizontalLayout.addWidget(self.btn)
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtGui.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 600, 22))
self.menubar.setObjectName("menubar")
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtGui.QStatusBar(MainWindow)
self.statusbar.setObjectName("statusbar")
MainWindow.setStatusBar(self.statusbar)
self.retranslateUi(MainWindow)
QtCore.QMetaObject.connectSlotsByName(MainWindow)
def retranslateUi(self, MainWindow):
MainWindow.setWindowTitle(QtGui.QApplication.translate("MainWindow", "MainWindow", None, QtGui.QApplication.UnicodeUTF8))
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
【问题讨论】：
【参考方案1】：这并不能解决所有问题，但是将 dropMimeData() 更改为以下内容至少可以移动叶子项目。
self.beginInsertRows(parentIndex, row, row)
parentIndex.internalPointer().add_child_obj(Branch(item.get_name(), item.get_value(), parent), row)
self.endInsertRows()
拖放操作实际上是两个步骤，插入（在 dropMimeData 中完成）和删除（通过移动拖动操作自动完成）。上面的更改插入了一个新项目，而不是尝试插入一个已经在模型中并且在插入发生后将从旧位置删除的项目。
【讨论】：
baysmith，非常感谢。那解决了它！我认为现在对我来说很有意义......当我重新设置对象时，QTreeView 现在有两个索引指向同一个对象。然后，当它删除“旧”对象时，它会以某种方式删除对该对象的所有引用（这就是您在帖子中所说的）。问：你说它不能解决所有问题。你看别人吗？我对此很陌生，并且渴望学习。再次感谢！这让我发疯了。 如果带有子项的项被移动，子项将丢失，因为 dropMimeData 只复制拖动项的名称和值。它可能也应该让孩子们感动。 另外，add_child_obj 函数不会更新子对象的父引用。 supportedDropActions 函数定义了两次。 insertRow 和 removeRow 函数在 QAbstractItemModel 上不是虚拟函数，因此可能不应该在自定义模型中被覆盖。 贝史密斯。这真太了不起了。非常感谢你的帮助。它真的帮助我了解整个过程。我已经解决了丢失儿童的问题，但甚至没有考虑其他问题。再次感谢。以上是关于qt: pyqt: QTreeView 内部拖放几乎可以正常工作...被拖动的项目消失了的主要内容，如果未能解决你的问题，请参考以下文章