What deletes the widget created by a custom QItemDelegate

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+1 Q:

What deletes the widget created by a custom QItemDelegate

Working with the Qt ItemViews the editing widget of an item can be modified via a QItemDelegate that can create a custom editor via createEditor. Who is responsible for deleting the instance created by the delegate.

I could not find any documentation that explained this, if you just point to the appropriate section that is fine

QObjects generally take care of themselves as long as their parent is set. When you call createEditor() and specify a parent in the first parameter, the parent will take care of deleting it.

The relevant documentation can be found here, in particular, the third paragraph of the description.

Arnold Spence 2010-09-27 22:37:57

I know about Qt parent-child memory management. In this case this would mean that all the widgets that get created when somebody wants to edit a table item would only get cleaned up when the the view (the parent in this case) gets deleted, this does not sound like a clean solution

Harald Scheirich 2010-09-28 09:47:53

I understand your concern a bit better now. If this is indeed the behavior and a lot of items are edited, a lot of items will be created and left hanging around. I attempted to browse the source code to see what might be happening but it is not easy code to browse :) An experiment might help though. In your implementation of createEditor, connect a slot to the new objects destroyed() signal with some cout info and see if you can tell when they get deleted. Also, I would assume that only one item can be edited at a time, maybe always return the same item. Sorry I couldn't find more solid info.

Arnold Spence 2010-09-28 13:12:48

I put a breakpoint on the destructor and followed that back, thanks for the help

Harald Scheirich 2010-09-28 13:17:53

+3 A:

Allright, I did trace this back ...

An editor widget created by a subclass created by QAbstractItemDelegate will get deleted after it has lost focus and the whole signal chain that is documented under delegation has been triggered. It is actually deleted via a deleteLater() call in the QAbstractItemView.

There is the concept of a persistent editor but I did not follow that any further

Harald Scheirich 2010-09-28 13:19:57

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What deletes the widget created by a custom QItemDelegate

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