[PyQt] itemview drag and drop problems

[Adam Tenderholt]

I've been playing around with the PyQt4.3a1 windows binary package and
have run into some problems. ItemViews appear to ignore the
ItemIsDropEnabled flag for top level items. Attached is a modified
simpletreemodel script that enables drags and drops for all items. Any
item can be dragged, but drops to top level items aren't allowed while
drops to second-level items are allowed. (Of course the code isn't
setup to accept drops, so there will be an error if you try to drop.)

It works as expected using PyQt 4.1.1 (yes, I'm a few releases behind)
on Windows (Python 2.4.3) and PyQt 4.1 on Mac (Python 2.4.3).

Any ideas?

Adam
-------------- next part --------------
#!/usr/bin/env python

"""***************************************************************************
**
** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at sales at trolltech.com.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
***************************************************************************"""

import sys
from PyQt4 import QtCore, QtGui

import simpletreemodel_rc


class TreeItem:
    def __init__(self, data, parent=None):
        self.parentItem = parent
        self.itemData = data
        self.childItems = []

    def appendChild(self, item):
        self.childItems.append(item)

    def child(self, row):
        return self.childItems[row]

    def childCount(self):
        return len(self.childItems)

    def columnCount(self):
        return len(self.itemData)

    def data(self, column):
        return self.itemData[column]

    def parent(self):
        return self.parentItem

    def row(self):
        if self.parentItem:
            return self.parentItem.childItems.index(self)

        return 0


class TreeModel(QtCore.QAbstractItemModel):
    def __init__(self, data, parent=None):
        QtCore.QAbstractItemModel.__init__(self, parent)

        rootData = []
        rootData.append(QtCore.QVariant("Title"))
        rootData.append(QtCore.QVariant("Summary"))
        self.rootItem = TreeItem(rootData)
        self.setupModelData(data.split("\n"), self.rootItem)

    def columnCount(self, parent):
        if parent.isValid():
            return parent.internalPointer().columnCount()
        else:
            return self.rootItem.columnCount()

    def data(self, index, role):
        if not index.isValid():
            return QtCore.QVariant()

        if role != QtCore.Qt.DisplayRole:
            return QtCore.QVariant()

        item = index.internalPointer()

        return QtCore.QVariant(item.data(index.column()))

    def flags(self, index):
        if not index.isValid():
            return QtCore.Qt.ItemIsEnabled

        return QtCore.Qt.ItemIsEnabled | QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsDragEnabled | QtCore.Qt.ItemIsDropEnabled | QtCore.Qt.ItemIsEditable

    def headerData(self, section, orientation, role):
        if orientation == QtCore.Qt.Horizontal and role == QtCore.Qt.DisplayRole:
            return self.rootItem.data(section)

        return QtCore.QVariant()

    def index(self, row, column, parent):
        if row < 0 or column < 0 or row >= self.rowCount(parent) or column >= self.columnCount(parent):
            return QtCore.QModelIndex()

        if not parent.isValid():
            parentItem = self.rootItem
        else:
            parentItem = parent.internalPointer()

        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:
            return QtCore.QModelIndex()

        return self.createIndex(parentItem.row(), 0, parentItem)

    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 setupModelData(self, lines, parent):
        parents = []
        indentations = []
        parents.append(parent)
        indentations.append(0)

        number = 0

        while number < len(lines):
            position = 0
            while position < len(lines[number]):
                if lines[number][position] != " ":
                    break
                position += 1

            lineData = lines[number][position:].trimmed()

            if not lineData.isEmpty():
                # Read the column data from the rest of the line.
                columnStrings = lineData.split("\t", QtCore.QString.SkipEmptyParts)
                columnData = []
                for column in range(0, len(columnStrings)):
                    columnData.append(columnStrings[column])

                if position > indentations[-1]:
                    # The last child of the current parent is now the new parent
                    # unless the current parent has no children.

                    if parents[-1].childCount() > 0:
                        parents.append(parents[-1].child(parents[-1].childCount() - 1))
                        indentations.append(position)

                else:
                    while position < indentations[-1] and len(parents) > 0:
                        parents.pop()
                        indentations.pop()

                # Append a new item to the current parent's list of children.
                parents[-1].appendChild(TreeItem(columnData, parents[-1]))

            number += 1


if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)

    f = QtCore.QFile(":/default.txt")
    f.open(QtCore.QIODevice.ReadOnly)
    model = TreeModel(QtCore.QString(f.readAll()))
    f.close()

    view = QtGui.QTreeView()
    view.setModel(model)
    view.setWindowTitle("Simple Tree Model")
    view.setDragEnabled(True)
    view.setAcceptDrops(True)
    view.setSelectionMode(QtGui.QTreeView.ExtendedSelection)
    view.show()
    sys.exit(app.exec_())