A custom Python class-based 1D model

On 2010年04月12日, on the #pyqt channel on Freenode, rowinggolfer pasted the following model with these remarks:

[18:20] <rowinggolfer> I played with a custom python class based 1d model, attached to a listview, and accessed via drag/drop.
[18:20] <rowinggolfer> I put the code up here for anyone to play with / fine tune.
[18:20] <rowinggolfer> http://paste.debian.net/68590/
[18:21] <rowinggolfer> there's a couple of standard (?) tricks in there... using QUserRole to get the actual python object passed to the QDrag as an argument
[18:21] <rowinggolfer> and converting to a bytestream using pickle
[18:22] <rowinggolfer> I also played with generating a nice pixmap for the drag, but decided that the grabwidget method is easiest.

 1 import datetime
 2 import cPickle
 3 import pickle
 4 import sys
 5 
 6 from PyQt4 import QtGui, QtCore
 7 
 8 class person(object):
 9  '''
 10  a custom data structure, for example purposes
 11  '''
 12  def __init__(self, name, dob, house_no):
 13  self.name = name
 14  self.dob = dob
 15  self.addr = "%d Rue de la Soleil"% house_no
 16  def __repr__(self):
 17  return "%s\n%s\n%s"% (self.name, self.dob, self.addr)
 18 
 19 class simple_model(QtCore.QAbstractListModel):
 20  def __init__(self, parent=None):
 21  super(simple_model, self).__init__(parent)
 22  self.list = []
 23  for name, dob, house_no in (
 24  ("Neil", datetime.date(1969,12,9), 23),
 25  ("John", datetime.date(1952,5,3), 2543),
 26  ("Ilona", datetime.date(1975,4,6), 1)):
 27  self.list.append(person(name, dob, house_no))
 28  self.setSupportedDragActions(QtCore.Qt.MoveAction)
 29 
 30  def rowCount(self, parent=QtCore.QModelIndex()):
 31  return len(self.list)
 32 
 33  def data(self, index, role):
 34  if role == QtCore.Qt.DisplayRole: #show just the name
 35  person = self.list[index.row()]
 36  return QtCore.QVariant(person.name)
 37  elif role == QtCore.Qt.UserRole: #return the whole python object
 38  person = self.list[index.row()]
 39  return person
 40  return QtCore.QVariant()
 41 
 42  def removeRow(self, position):
 43  self.list = self.list[:position] + self.list[position+1:]
 44  self.reset()
 45 
 46 class dropZone(QtGui.QLabel):
 47  def __init__(self, parent=None):
 48  super(dropZone, self).__init__(parent)
 49  self.setMinimumSize(200,200)
 50  self.set_bg()
 51  self.setText("Drop Here")
 52  self.setAlignment(QtCore.Qt.AlignCenter)
 53  self.setAcceptDrops(True)
 54 
 55  def dragEnterEvent(self, event):
 56  if event.mimeData().hasFormat("application/x-person"):
 57  self.set_bg(True)
 58  event.accept()
 59  else:
 60  event.ignore()
 61 
 62  def dragMoveEvent(self, event):
 63  if event.mimeData().hasFormat("application/x-person"):
 64  event.setDropAction(QtCore.Qt.MoveAction)
 65  event.accept()
 66  else:
 67  event.ignore()
 68 
 69  def dragLeaveEvent(self, event):
 70  self.set_bg()
 71 
 72  def dropEvent(self, event):
 73  data = event.mimeData()
 74  bstream = data.retrieveData("application/x-person",
 75  QtCore.QVariant.ByteArray)
 76  selected = pickle.loads(bstream.toByteArray())
 77  self.setText(str(selected))
 78  self.set_bg()
 79  event.accept()
 80 
 81  def set_bg(self, active=False):
 82  if active:
 83  val = "background:yellow;"
 84  else:
 85  val = "background:green;"
 86  self.setStyleSheet(val)
 87 
 88 
 89 class draggableList(QtGui.QListView):
 90  '''
 91  a listView whose items can be moved
 92  '''
 93  def ___init__(self, parent=None):
 94  super(draggableList, self).__init__(parent)
 95  self.setDragEnabled(True)
 96 
 97  def dragEnterEvent(self, event):
 98  if event.mimeData().hasFormat("application/x-person"):
 99  event.setDropAction(QtCore.Qt.QMoveAction)
 100  event.accept()
 101  else:
 102  event.ignore()
 103 
 104  def startDrag(self, event):
 105  index = self.indexAt(event.pos())
 106  if not index.isValid():
 107  return
 108 
 109  ## selected is the relevant person object
 110  selected = self.model().data(index,QtCore.Qt.UserRole)
 111 
 112  ## convert to a bytestream
 113  bstream = cPickle.dumps(selected)
 114  mimeData = QtCore.QMimeData()
 115  mimeData.setData("application/x-person", bstream)
 116 
 117  drag = QtGui.QDrag(self)
 118  drag.setMimeData(mimeData)
 119 
 120  # example 1 - the object itself
 121 
 122  pixmap = QtGui.QPixmap()
 123  pixmap = pixmap.grabWidget(self, self.rectForIndex(index))
 124 
 125  # example 2 - a plain pixmap
 126  #pixmap = QtGui.QPixmap(100, self.height()/2)
 127  #pixmap.fill(QtGui.QColor("orange"))
 128  drag.setPixmap(pixmap)
 129 
 130  drag.setHotSpot(QtCore.QPoint(pixmap.width()/2, pixmap.height()/2))
 131  drag.setPixmap(pixmap)
 132  result = drag.start(QtCore.Qt.MoveAction)
 133  if result: # == QtCore.Qt.MoveAction:
 134  self.model().removeRow(index.row())
 135 
 136  def mouseMoveEvent(self, event):
 137  self.startDrag(event)
 138 
 139 class testDialog(QtGui.QDialog):
 140  def __init__(self, parent=None):
 141  super(testDialog, self).__init__(parent)
 142  self.setWindowTitle("Drag Drop Test")
 143  layout = QtGui.QGridLayout(self)
 144 
 145  label = QtGui.QLabel("Drag Name From This List")
 146 
 147  self.model = simple_model()
 148  self.listView = draggableList()
 149  self.listView.setModel(self.model)
 150  self.dz = dropZone()
 151 
 152  layout.addWidget(label,0,0)
 153  layout.addWidget(self.listView,1,0)
 154  layout.addWidget(self.dz,0,1,2,2)
 155 
 156 if __name__ == "__main__":
 157  '''
 158  the try catch here is to ensure that the app exits cleanly no matter what
 159  makes life better for SPE
 160  '''
 161  try:
 162  app = QtGui.QApplication([])
 163  dl = testDialog()
 164  dl.exec_()
 165  except Exception, e: #could use as e for python 2.6...
 166  print e
 167  sys.exit(app.closeAllWindows())