[PySide] QListView: drag&drop custom item

[Frank Rueter | OHUfx]

In case somebody else is interested, turns out that I can simply use 
setItemPrototype() on the receiving model to make it use my custom item 
whenever necessary.
This should do away with all the other manual handling of dropped items, 
mime data etc.

Cheers,
frank

On 09/19/2016 08:47 PM, Frank Rueter | OHUfx wrote:
> And one more follow up before I give up for the day:
> I found some code online that decodes the byte stream returned by a 
> QDropEvent.mimeData().data() method so I get the item instance back.
> I worked that function into my example but the model refuses to append 
> the dropped item.
> A new instance of my custom item inside the drop event appends just 
> fine, but not the actual dropped item or a copy of it. I just can't 
> see what's wrong with this. Can somebody please have a look?
> http://pastebin.com/UWWGXfNQ
>
> If this fails I guess I will have to create a new item on the fly and 
> make sure to copy all relevant data across, though that seems 
> unnecessary and error prone.
>
> Cheers,
> frank
>
>
> On 19/09/16 7:51 PM, Frank Rueter | OHUfx wrote:
>> Thanks Jukka,
>>
>> that's probably not a bad idea considering how much time I have spent 
>> trying to get this to work via QT.
>> I had been toying with the idea of just sending a dictionary of the 
>> relevant data, probably via a custom mime type, then re-creating the 
>> custom item upon drop in the receiving view.
>> I will keep that in mind as my last resort, but it feels like the 
>> default implementation of the drop behaviour is soooo close, that it 
>> should be possible to drop a custom item in some QT-ish way without 
>> re-invening the wheel - or is that too optimistic?
>>
>> Here is a simple test code, hopefully we can get some more input with 
>> that:
>> http://pastebin.com/5UDPQFjh
>>
>> With this code, when dropping an item fro the left into the right 
>> view, the print statement shows that a QStandardItem is produced 
>> rather than the custom item.
>>
>> Any more takers?
>>
>> Cheers,
>> frank
>>
>> On 19/09/16 7:31 PM, Purma Jukka wrote:
>>> Hi,
>>> since you asked any ideas... In my app I have had to re-invent 
>>> drag&drop for some items (because I want to drag QGraphicsItems in 
>>> scene while having all kinds of effects on the items they are 
>>> connected while keeping the main event loop running etc. ) and 
>>> learned a habit to give up when I didn’t find Qt-way of doing things 
>>> and instead to choose the simplest pythonesque way.
>>>
>>> So in your case at this point, I would have
>>> 1. 'start drag' store the dragged data, just the main payload, not 
>>> the Q-item containing them, in some stable object (main window), 
>>> just as ’main.dragged_object’.
>>> 2. when drag gets dropped to those problem recipients, in drop 
>>> event, manually put the data from main window into recipient, 
>>> without bothering with the Q-representations of the data.
>>>
>>> In my app I have a multipurpose controller-object and ctrl.dragged 
>>> is used to store the non-qt data of whatever is being dragged. It 
>>> was my solution to struggle with QStandardItems and such.
>>>
>>> In conclusion, since we are doing things with Python + Qt, I think 
>>> we are justified to skip Qt when there is an easier (or more 
>>> readable) pythonesque way of doing things.
>>>
>>> Jukka
>>>
>>>> Frank Rueter | OHUfx <frank at ohufx.com> kirjoitti 19.9.2016 kello 9.56:
>>>>
>>>> Anybody?
>>>> I'm still struggling with this. I went back to using a 
>>>> QStandardItem for a while which solved the dag&drop behaviour, but 
>>>> now I really need to use a custom item that inherits QStandardItem 
>>>> which breaks the drop behaviour again.
>>>>
>>>> Any ideas or guidance would be greatly appreciated.
>>>>
>>>> Cheers,
>>>> frank
>>>>
>>>>
>>>> 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 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
>>>>>
>>>>>
>>>>>
>>>>> -- 
>>>>> <Sähköpostiliite.png>    vfx compositing | workflow customisation 
>>>>> and consulting
>>>>>
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