Drag and Drop with custom data - example required

wxPython Users
1

As the subject suggests; I've been banging my head against a brick wall for a couple of days now trying to get a simple drag and drop app working. I want to be able to drag'n'drop some data from a list control to another panel within the same app, but all the tutorials I've found talk about using the standard text versions. If anyone has any experience in dragging and dropping custom data, I'd be extremely grateful!

Thanks,
Jon

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2

Hi Jon,

As the subject suggests; I've been banging my head against a
brick wall for a couple of days now trying to get a simple
drag and drop app working. I want to be able to drag'n'drop
some data from a list control to another panel within the
same app, but all the tutorials I've found talk about using
the standard text versions. If anyone has any experience in
dragging and dropping custom data, I'd be extremely grateful!

You could try something like this:

import cPickle
import weakref

class DragInfo:

    _map = weakref.WeakValueDictionary()

    def __init__(self, data):
        """ Default class constructor. """
        
        self._id = id(data)
        DragInfo._map[self._id] = data

    def GetMyData(self):
        """ Returns the data. """
        
        return DragInfo._map.get(self._id, None)

class DropTarget(wx.DropTarget):

    def __init__(self, parent):
        """ Default class constructor. """
        
        wx.DropTarget.__init__(self)

        self._parent = parent
        self._dataobject = wx.CustomDataObject(wx.CustomDataFormat("MySpecialData"))
        self.SetDataObject(self._dataobject)

    def OnData(self, x, y, dragres):
        """ Handles the OnData() method to call the real DnD routine. """

        if not self.GetData():
            return wx.DragNone

        draginfo = self._dataobject.GetData()
        drginfo = cPickle.loads(draginfo)

        if not drginfo.GetMyData():
            return wx.DragNone
        
        return self._parent.OnDropTarget(x, y, drginfo.GetMyData())

# If you defined an event like OnBeginDrag in your ListCtrl
def OnBeginDrag(self, event):

        draginfo = cPickle.dumps(DragInfo(item))
        dataobject = wx.CustomDataObject(wx.CustomDataFormat("MySpecialData"))
        dataobject.SetData(draginfo)
        dragSource = wx.DropSource(self)
        dragSource.SetData(dataobject)
        dragSource.DoDragDrop(wx.Drag_DefaultMove)
        event.Skip()

# Then, in your panel (drop target) you can do:

def OnDropTarget(self, x, y, myData):
        """ Handles the drop action from a DND operation. """

        # do whatever you like here with myData
        return wx.DragMove

I hope this helps...

Andrea.

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Reservoir Engineer
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SW1P 3JA London

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3

Jon Cage wrote:

As the subject suggests; I've been banging my head against a brick wall for a couple of days now trying to get a simple drag and drop app working. I want to be able to drag'n'drop some data from a list control to another panel within the same app, but all the tutorials I've found talk about using the standard text versions. If anyone has any experience in dragging and dropping custom data, I'd be extremely grateful!

Have you looked at the CustomDragAndDrop module in the demo?

···

--
Robin Dunn
Software Craftsman
http://wxPython.org Java give you jitters? Relax with wxPython!