QTreeWidget expand animation on double click

Question

I have created a QTreeWidget and set animation to true (setAnimated(true)). When I'm clicking on a mark (triangle) at the left of item it expands smoothly, but when I'm double clicking on the item it expands too fast (almost like there is no "animated" flag set). I want smooth animation on double click too. How can I solve this problem?

QTreeView calls QTreeViewPrivate::expandOrCollapseItemAtPos on mark click and QTreeViewPrivate::expand on double click, so I have no access to these methods.

I'm using PySide for creating Qt application (but I've tried C++ and the problem is the same).

Answer 1

You need to override the click behaviour. Check the event if it's a double click or not and then you can redirect the event to the appropriate call. You should check the state if it's already clicked or not to prevent a second animation which might happen.

Answer 2

The trick is, double click also rise a single click in default implementation. Before expand animation, the default implementation call QAbstractItemView::setState(AnimatingState) to set internal state for animation.

And in QAbstractItemView::mouseReleaseEvent(), QAbstractItemView::setState(NoState) is called before animation finished. After this, animation terminated immediately.

Use following code to work around:

void YourSubTreeView::mouseReleaseEvent(QMouseEvent* event)
{
    QAbstractItemView::State preState = state();
    QTreeView::mouseReleaseEvent(event);
    if (preState == QAbstractItemView::AnimatingState)
        setState(preState);
}