[Interest] Model/Views and Drag&Drop actions

[Etienne Sandré-Chardonnal]

Qt::DropActions is a bitmask. The issue I suspect is that instead of:

e->dropAction() & model->supportedDropActions()

we should have:

e->possibleActions() & model->supportedDropActions()

So that any action common to both the source model dragActions() and the
destination model dropActions() can be used.

Etienne

2017-03-27 19:20 GMT+02:00 Jason H <jhihn at gmx.com>:

> With the &, it looks like it's using a bitmask. Make sure that the
> dropAction() and supportedDropActions() values are arranged correctly, as a
> bitmask.
>
>
> 00100 * 00111  = 00100, return true. Therefore the only other thing is it
> is a mime issue?
>
> *Sent:* Monday, March 27, 2017 at 9:28 AM
> *From:* "Etienne Sandré-Chardonnal" <etienne.sandre at m4x.org>
> *To:* "interest at qt-project.org" <Interest at qt-project.org>
> *Subject:* [Interest] Model/Views and Drag&Drop actions
> Dear all,
>
> I have two custom models associated with views and I would like to drag
> from model A and drop into model B.
>
> Model B has overloaded supportedDropActions and returns Qt::LinkAction
>
> Model A has overloaded supportedDragActions and returns Qt::MoveAction |
> Qt::LinkAction
>
> This does not work as the cursor turns to a forbidden sign when dragging
> over B.
>
> If model A supportedDragActions returns Qt::LinkAction only, then this
> works.
>
>
>
> If I look to the source code of QAbstractItemViewPrivate, i find in
> canDecode(QDropEvent * e):
>
>             if (mime->hasFormat(modelTypes.at(i))
>                && (e->dropAction() & model->supportedDropActions()))
>                 return true;
>
> Which explains the issue, the event handler does not check the event's
> possible drop actions and does not call setDropAction if the proposed
> action is not supported.
>
> Is this a bug or a feature?
>
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