I'm using my custom item model (subclassed from QAbstractItemModel) with custom QTreeView. I want to allow internal drag-n-drop movement (MoveAction) and, when modifier key or right mouse button is pressed, pass CopyAction to my model (to dropMimeData) to copy items. However, default implementation of dropEvent() in QTreeView seems (from C code) only capable of passing MoveAction but when I try to reimplement dropEvent() in my QTreeView subclass like this:
def dropEvent(self, e):
index = self.indexAt(e.pos())
parent = index.parent()
self.model().dropMimeData(e.mimeData(), e.dropAction(), index.row(), index.column(), parent)
e.accept()
... it works, but works horribly in terms of user interaction because there are tons of comlex code determining right index to drop item on in default implementation.
When i'm trying to modify action and call to superclass: super(Tree, self).dropEvent(e) dropAction() data is also lost.
What can I do in order to modify dropAction without loosing all fancy things that default dropEvent is doing for me?
Horrible mess of my current WIP code (i hope it's somewhere near minimal example)
from copy import deepcopy
import pickle
import config_editor
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt as Qt
from PyQt5.QtGui import QCursor, QStandardItemModel
from PyQt5.QtWidgets import QAbstractItemView, QTreeView, QMenu
class ConfigModelItem:
def __init__(self, label, value="", is_section=False, state='default', parent=None):
self.itemData = [label, value]
self.is_section = is_section
self.state = state
self.childItems = []
self.parentItem = parent
if self.parentItem is not None:
self.parentItem.appendChild(self)
def appendChild(self, item):
self.childItems.append(item)
item.parentItem = self
def addChildren(self, items, row):
if row == -1:
row = 0
self.childItems[row:row] = items
for item in items:
item.parentItem = self
def child(self, row):
return self.childItems[row]
def childCount(self):
return len(self.childItems)
def columnCount(self):
return 2
def data(self, column):
try:
return self.itemData[column]
except IndexError:
return None
def set_data(self, data, column):
try:
self.itemData[column] = data
except IndexError:
return False
return True
def parent(self):
return self.parentItem
def row(self):
if self.parentItem is not None:
return self.parentItem.childItems.index(self)
return 0
def removeChild(self, position):
if position < 0 or position > len(self.childItems):
return False
child = self.childItems.pop(position)
child.parentItem = None
return True
def __repr__(self):
return str(self.itemData)
class ConfigModel(QtCore.QAbstractItemModel):
def __init__(self, data, parent=None):
super(ConfigModel, self).__init__(parent)
self.rootItem = ConfigModelItem("Option", "Value")
self.setup(data)
def headerData(self, section, orientation, role):
if role == Qt.DisplayRole and orientation == Qt.Horizontal:
return self.rootItem.data(section)
def columnCount(self, parent):
return 2
def rowCount(self, parent):
if parent.column() > 0:
return 0
if not parent.isValid():
parentItem = self.rootItem
else:
parentItem = parent.internalPointer()
return parentItem.childCount()
def index(self, row, column, parent):
if not self.hasIndex(row, column, parent):
return QtCore.QModelIndex()
parentItem = self.nodeFromIndex(parent)
childItem = parentItem.child(row)
if childItem:
return self.createIndex(row, column, childItem)
else:
return QtCore.QModelIndex()
def parent(self, index):
if not index.isValid():
return QtCore.QModelIndex()
childItem = index.internalPointer()
parentItem = childItem.parent()
if parentItem == self.rootItem or parentItem is None:
return QtCore.QModelIndex()
return self.createIndex(parentItem.row(), 0, parentItem)
def nodeFromIndex(self, index):
if index.isValid():
return index.internalPointer()
return self.rootItem
def data(self, index, role):
if not index.isValid():
return None
item = index.internalPointer()
if role == Qt.DisplayRole or role == Qt.EditRole:
return item.data(index.column())
return None
def setData(self, index, value, role=Qt.EditRole):
if not index.isValid():
return False
item = index.internalPointer()
if role == Qt.EditRole:
item.set_data(value, index.column())
self.dataChanged.emit(index, index, (role,))
return True
def flags(self, index):
if not index.isValid():
return QtCore.Qt.ItemIsDragEnabled | QtCore.Qt.ItemIsDropEnabled # Qt.NoItemFlags
item = index.internalPointer()
flags = Qt.ItemIsEnabled | Qt.ItemIsSelectable
if index.column() == 0:
flags |= int(QtCore.Qt.ItemIsDragEnabled)
if item.is_section:
flags |= int(QtCore.Qt.ItemIsDropEnabled)
if index.column() == 1 and not item.is_section:
flags |= Qt.ItemIsEditable
return flags
def supportedDropActions(self):
return QtCore.Qt.CopyAction | QtCore.Qt.MoveAction
def mimeTypes(self):
return ['app/configitem', 'text/xml']
def mimeData(self, indexes):
mimedata = QtCore.QMimeData()
index = indexes[0]
mimedata.setData('app/configitem', pickle.dumps(self.nodeFromIndex(index)))
return mimedata
def dropMimeData(self, mimedata, action, row, column, parentIndex):
print('action', action)
if action == Qt.IgnoreAction:
return True
droppedNode = deepcopy(pickle.loads(mimedata.data('app/configitem')))
print('copy', action & Qt.CopyAction)
print(droppedNode.itemData, 'node')
self.insertItems(row, [droppedNode], parentIndex)
self.dataChanged.emit(parentIndex, parentIndex)
if action & Qt.CopyAction:
return False # to not delete original item
return True
def removeRows(self, row, count, parent):
print('rem', row, count)
self.beginRemoveRows(parent, row, row+count-1)
parentItem = self.nodeFromIndex(parent)
for x in range(count):
parentItem.removeChild(row)
self.endRemoveRows()
print('removed')
return True
@QtCore.pyqtSlot()
def removeRow(self, index):
parent = index.parent()
self.beginRemoveRows(parent, index.row(), index.row())
parentItem = self.nodeFromIndex(parent)
parentItem.removeChild(index.row())
self.endRemoveRows()
return True
def insertItems(self, row, items, parentIndex):
print('ins', row)
parent = self.nodeFromIndex(parentIndex)
self.beginInsertRows(parentIndex, row, row+len(items)-1)
parent.addChildren(items, row)
print(parent.childItems)
self.endInsertRows()
self.dataChanged.emit(parentIndex, parentIndex)
return True
def setup(self, data: dict, parent=None):
if parent is None:
parent = self.rootItem
for key, value in data.items():
if isinstance(value, dict):
item = ConfigModelItem(key, parent=parent, is_section=True)
self.setup(value, parent=item)
else:
parent.appendChild(ConfigModelItem(key, value))
def to_dict(self, parent=None) -> dict:
if parent is None:
parent = self.rootItem
data = {}
for item in parent.childItems:
item_name, item_data = item.itemData
if item.childItems:
data[item_name] = self.to_dict(item)
else:
data[item_name] = item_data
return data
@property
def dict(self):
return self.to_dict()
class ConfigDialog(config_editor.Ui_config_dialog):
def __init__(self, data):
super(ConfigDialog, self).__init__()
self.model = ConfigModel(data)
def setupUi(self, config_dialog):
super(ConfigDialog, self).setupUi(config_dialog)
self.config_view = Tree()
self.config_view.setObjectName("config_view")
self.config_view.setModel(self.model)
self.gridLayout.addWidget(self.config_view, 0, 0, 1, 1)
self.config_view.expandAll()
#self.config_view.setDragDropMode(True)
#self.setDragDropMode(QAbstractItemView.InternalMove)
#self.setDragEnabled(True)
#self.setAcceptDrops(True)
#self.setDropIndicatorShown(True)
self.delete_button.pressed.connect(self.remove_selected)
def remove_selected(self):
index = self.config_view.selectedIndexes()[0]
self.model.removeRow(index)\
class Tree(QTreeView):
def __init__(self):
QTreeView.__init__(self)
self.setContextMenuPolicy(Qt.CustomContextMenu)
self.customContextMenuRequested.connect(self.open_menu)
self.setSelectionMode(self.SingleSelection)
self.setDragDropMode(QAbstractItemView.InternalMove)
self.setDragEnabled(True)
self.setAcceptDrops(True)
self.setDropIndicatorShown(True)
self.setAnimated(True)
def dropEvent(self, e):
print(e.dropAction(), 'baseact', QtCore.Qt.CopyAction)
# if e.keyboardModifiers() & QtCore.Qt.AltModifier:
# #e.setDropAction(QtCore.Qt.CopyAction)
# print('copy')
# else:
# #e.setDropAction(QtCore.Qt.MoveAction)
# print("drop")
print(e.dropAction())
#super(Tree, self).dropEvent(e)
index = self.indexAt(e.pos())
parent = index.parent()
print('in', index.row())
self.model().dropMimeData(e.mimeData(), e.dropAction(), index.row(), index.column(), parent)
e.accept()
def open_menu(self):
menu = QMenu()
menu.addAction("Create new item")
menu.exec_(QCursor.pos())
if __name__ == '__main__':
import sys
def except_hook(cls, exception, traceback):
sys.__excepthook__(cls, exception, traceback)
sys.excepthook = except_hook
app = QtWidgets.QApplication(sys.argv)
Dialog = QtWidgets.QDialog()
data = {"section 1": {"opt1": "str", "opt2": 123, "opt3": 1.23, "opt4": False, "...": {'subopt': 'bal'}},
"section 2": {"opt1": "str", "opt2": [1.1, 2.3, 34], "opt3": 1.23, "opt4": False, "...": ""}}
ui = ConfigDialog(data)
ui.setupUi(Dialog)
print(Qt.DisplayRole)
Dialog.show()
print(app.exec_())
print(Dialog.result())
print(ui.model.to_dict())
sys.exit()
setDragDropMode(QAbstractItemView.InternalMove) only allows move operations (as the name would suggest, although the docs do leave some uncertainty in the way this is stated). You probably want to set it to QAbstractItemView.DragDrop mode. You can set the default action with setDefaultDropAction(). Other than that, it's up to the model to return the right item flags and supportedDropActions()/canDropMimeData(), which it looks like yours does. There's also a dragDropOverwriteMode property which may be interesting.
One thing that has surprised me before is that in the model's dropMimeData() method if you return True from a Qt.MoveAction, the QAbstractItemView will remove the dragged item from the model automatically (with a removeRows()/removeColumns() call to your model). This can cause some puzzling results if your model has already actually moved that row (and deleted the old one). I never quite understood that behavior. OTOH if you return False it doesn't matter to the item view, as long as the data is actually moved/updated properly.