[Interest] QListView: drag&drop custom item

[Frank Rueter | OHUfx]

Thanks, but that still causes the default drag&drop behaviour to drop a 
QStandardItem rather than the subclassed custom item that was dragged. 
It's not the data that is the issue but the class type itself.

I have now refactored my code to use QStdandardItem instead of a custom 
one which makes it all work, but I'd still be quite interested to know 
the best way to do this (drag&drop a custom item between two QListViews 
in the same application).


Cheers,
frank

On 17/08/16 8:24 PM, Viktor Engelmann wrote:
>
> The QStandardItem seems to be used to limit the drag&drop to files, 
> images, text etc. so that you can drag & drop from and to external 
> applications (which is not possible for general objects).
>
> http://doc.qt.io/qt-4.8/qstandarditem.html#subclassing says you should 
> subclass QStandardItem and override read and write or data and 
> setData. That is probably used to marshal and unmashal the objects, to 
> make them compatible to text, which can be passed to and from external 
> applications.
>
> Viktor
>
>
> On 16.08.2016 23:56, Frank Rueter | OHUfx wrote:
>> Anybody?
>> I can find plenty of examples on how to drag items from a view to a 
>> widget but can't find anything about dragging a custom item from one 
>> view to another.
>> Guess I will start to re-implement the entire drag&drop, maybe the 
>> solution will become apparent then.
>>
>>
>> On 16/08/16 7:26 PM, Frank Rueter | OHUfx wrote:
>>> Hi,
>>>
>>> I am trying to get drag&drop to work between two QListViews using a 
>>> custom item.
>>> I can't find the info I need online other than this document 
>>> <https://doc.qt.io/archives/4.6/model-view-dnd.html> which helped a 
>>> little bit but now I'm stuck.
>>>
>>> Drag&drop from one QListView to another works fine when I use a 
>>> QStandardItem to hold my data, but when I use a custom item I run 
>>> into trouble, because the receiving model/view creates a 
>>> QStandardItem when the incoming custom items are dropped.
>>>
>>> Ideally I could tell the receiving model to use my custom item as 
>>> the default item and otherwise just do it's thing, but I suppose it 
>>> won't be that easy?!
>>> I have played around with the receiving model's dropMimeData() and 
>>> insertRows() methods but can't work out how to read the incoming 
>>> data to then insert a custom item into the receiving model manually.
>>> In QAbstractItemModel.dropMimeData() I tried reading 
>>> mimeData.data('application/x-qabstractitemmodeldatalist'), but that 
>>> returns a byte stream that I don't know how to handle.
>>>
>>> Do I have to re-implement the sender's drag data as well to send the 
>>> custom item in the first place?
>>>
>>> It seems that everything works out of the box except the creation of 
>>> the QStandardItem upon drop, rather than my custom item, so I am 
>>> hoping I don't have to re-invent the (drag&drop) wheel just to get 
>>> that one part right?!
>>>
>>> Any advise would be greatly appreciated.
>>>
>>> Thanks,
>>> frank
>>>
>>>
>>>
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