问题
I almost have a completely working drag and drop re-order within a QTreeView. Everything seems to be ok except the dropped object never appears (though I can reference it numerous different ways that proves to me that it actually exists where it should be). If anyone has a moment and could run the following code and let me know what I am doing wrong I would really appreciate it. I have been banging my head against this process for over a week now:
You should be able to just copy and run the following code (I have a bunch of print statements in it that seem to indicate that everything is working correctly but obviously something is off):
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_())
回答1:
This doesn't solve all the problems, but changing dropMimeData() to the following will at least allow moving leaf items.
self.beginInsertRows(parentIndex, row, row)
parentIndex.internalPointer().add_child_obj(Branch(item.get_name(), item.get_value(), parent), row)
self.endInsertRows()
A drag-drop operation is effectively two steps, an insert (done in dropMimeData) and a remove (done automatically by the Move drag operation). The changes above insert a new item rather than trying to insert an item which is already in the model and which will be removed from the old location after the insert occurs.
来源：https://stackoverflow.com/questions/4252114/qt-pyqt-qtreeview-internal-drag-and-drop-almost-working-dragged-item-disapp