[Fwd: RE: [wxPython-users] Drag and Drop with custom data - example required]

[Jon]

Fantastic!!
> Potential solution...
>
> -------- Original Message --------
> Subject: 	RE: [wxPython-users] Drag and Drop with custom data - 
> example required
> Date: 	Wed, 28 Feb 2007 13:18:36 -0000
> From: 	Gavana, Andrea <gavana at kpo.kz>
> Reply-To: 	wxPython-users at lists.wxwidgets.org
> To: 	<wxPython-users at lists.wxwidgets.org>
>
>
> 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.

I think I've almost got it. You can see the result here:

http://www.hyperlight.co.uk/hypersequencer/HyperGUI_v0_3.py

The only problem left to fix is that when I try to start to drag the 
text, I get this:

Started dragging
Traceback (most recent call last):
  File "D:\HyperLight Online\v4.0\HyperSequencer_Py\HyperGUI_v3.py", 
line 142, in OnBeginDrag
    dndData = DnD(text)
TypeError: this constructor takes no arguments

The DnD class will be a holder for the data that I'll be passing across. 
I'm quite new to Python so I've probably just overlooked something.. ? 
Can anyone spot it?

Thanks very much,

Jon