How to tell where an item was dropped in qlistview?

Question

I have a custom QListView:

from PyQt4.QtCore import *
from PyQt4.QtGui import *

from Diagnostics import Trace2 #writes to log file
import traceback

class ListOrderView(QListView):

    itemMoved = pyqtSignal(int, int, QStandardItem) # Old index, new index, item 

    def __init__(self, parent=None):
        try:
            super(ListOrderView, self).__init__(parent)

            self.setAcceptDrops(True)
            self.setDragEnabled(True)
            self.setDragDropMode(QAbstractItemView.InternalMove)
            self.setDefaultDropAction(Qt.MoveAction)

            self.setEditTriggers(QAbstractItemView.NoEditTriggers)
            self.setSelectionBehavior(QAbstractItemView.SelectRows)
            self.setSelectionMode(QAbstractItemView.SingleSelection)

            self.dragItem = None
            self.dragRow = None

            self.indexesMoved.connect(self.onIndexesMoved)
            #self.installEventFilter(self)
        except:
            Trace2.WriteLine(str(traceback.format_exc()))

    def onIndexesMoved(self, indexes):
        Trace2.WriteLine("indexes were moved")

    def dropEvent(self, event): 
        try:
            super(ListOrderView, self).dropEvent(event) 

            self.selectionModel().setCurrentIndex(self.model().indexFromItem(self.dragItem), QItemSelectionModel.SelectCurrent)
            Trace2.WriteLine("[LISTVIEW] item dropped")
            Trace2.WriteLine("[LISTVIEW] current index is %d" %self.selectionModel().currentIndex().row())
            Trace2.WriteLine("[LISTVIEW] current selection is %d" %self.selectionModel().selection().indexes()[0].row())

            self.itemMoved.emit(self.dragRow, self.row(self.dragItem), self.dragItem)
            self.dragItem = None
        except:
            Trace2.WriteLine(str(traceback.format_exc()))

    def startDrag(self, supportedActions): 
        try:
            self.dragItem = self.currentItem() 
            self.dragRow = self.row(self.dragItem) 
            super(ListOrderView, self).startDrag(Qt.MoveAction)
        except:
            Trace2.WriteLine(str(traceback.format_exc()))

    def currentItem(self):
        index = self.currentIndex()
        item = self.model().itemFromIndex(index)
        #Trace2.WriteLine("[LISTVIEW] currentItem = %s" % item.data(Qt.DisplayRole).toString())
        return item

    def row(self, item):
        #index = self.model().indexFromItem(item)
        index = self.selectedIndexes()[0]
        row = index.row()

        #Trace2.WriteLine("[LISTVIEW] row = %d" %row)
        return row

And I really need to know where the item was dropped after a drag and drop operation so other things can be properly updated (I'm trying to put drag and drop into something never designed for it, big app, not my design). The selection model's current index and selection don't follow the dropped item, they stay behind effectively selecting a new item and screwing things up. Is there a way to make them move with the dropped item? The signal indexesMoved seems exactly like what I want, but it never fires. Am I using it wrong? Is there a different/better way?

Answer 1

I think you might need to actually have the model tell you where something was dropped, since it will ultimately handle the move:

class Model(QStandardItemModel):

    rowDropped = pyqtSignal(int)

    def dropMimeData(self, *args):
        success =  super(Model, self).dropMimeData(*args)
        if success:
            self.rowDropped.emit(args[2])
        return success

This will emit, from the model, the row number on which the drop occurred. Your view already knows which item was dragged and dropped from its own events.

I am sure there are other ways in terms of tracking the object and then querying it again after the drop has completed.