Model Drag'n'Drop - Default Move

The QT reference article on models subclassing says that

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However, it is also possible to customize the way items are encoded during drag and drop operations, whether they are copied or moved by default, and how they are inserted into existing models.

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but I cannot find any evident way of setting the default drag/drop action to move and disabling the copy operation at all since there's no "copy" in my app.

Can someone give me a hint?

Thanks!

Hello Lemming,

I was facing the same problem a few days ago and to be short I don't find a way to solve this on the model side.

The model provides a method to tell which drop actions are supported:

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Qt::DropActions QAbstractItemModel::supportedDropActions () const

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This method must be overwritten and return Qt::MoveAction, so the model won't accept any "CopyDrops".

On the drag-site there is the method

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void QAbstractItemModel::setSupportedDragActions ( Qt::DropActions actions )

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which can be used to set the supported actions. These actions are queried by the view when a drop is started using QAbstractItemModel::supportedDragActions(), but somehow this doesn't work as expected, the standard list or tree view always creates a "CopyDrop", and I didn't find a way to prevent this.

The only thing you can do is to subclass the view you are using and overwrite the startDrag method, and force it to make a Qt::MoveAction when the drag event starts.

The above mentioned methods were introduced in qt-4.2 and I was trying with 4.2.1.

Hope it helps.

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Originally Posted by ggrinder

The only thing you can do is to subclass the view you are using and overwrite the startDrag method, and force it to make a Qt::MoveAction when the drag event starts.Hope it helps.

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That's exactly what I was thinking about but decided to leave for "Plan B".

Looks like I'll have to ask the Trolltech support...