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Thread: QTreeView expansion after model reset

  1. #1
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    Default QTreeView expansion after model reset

    I have a QTreeView that displays the contents of a custom QAbstractItemModel-based class. The custom model wraps a data structure that can be updated when the app recomputes results. When this happens, the model calls beginResetModel() / endResetModel(), which results in a modelReset() signal. All is fine with this part.

    When the tree view receives notification of an updated model, I want to expand the root item to display all of its top-level children. So, I have made a connection between the model's modelReset() signal and a slot in the widget that contains the QTreeView. In this slot, I call QTreeView::expandToDepth( 1 ). Unfortunately, it appears that this slot is being invoked before the tree view updates itself, because I can see the view's contents disappear and then reappear (unexpanded) after leaving the slot. (I have replaced the expandToDepth() call with expandAll() with the same result).

    Is there a way I can determine that the tree view has finished its internal update after a model reset so I can expand the root node?

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    Default Re: QTreeView expansion after model reset

    I would start a timer with a tiny interval upon receiving modelReset() and then expand the tree when it fires.
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    Default Re: QTreeView expansion after model reset

    Are you connecting after setting the model on the view?

    Otherwise you will get the reset signal before the view does.

    Cheers,
    _

  4. The following user says thank you to anda_skoa for this useful post:

    d_stranz (3rd December 2014)

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    Default Re: QTreeView expansion after model reset [SOLVED]

    Are you connecting after setting the model on the view?

    Otherwise you will get the reset signal before the view does.
    You nailed it. I had thought about the connection order, but I guess I assumed I was doing it in the right order. Reversing the order fixed it.
    Last edited by d_stranz; 4th December 2014 at 00:10.

  6. The following user says thank you to d_stranz for this useful post:

    neuronet (20th February 2015)

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