[Qt-interest] QtreeWidget::addTopLevelItem() very slow method

[Malyushytsky, Alex]

Combination of :

bool    QWidget::updatesEnabled () const
void    QWidget::setUpdatesEnabled ( bool enable )

may serve the same purpose and you can avoid creating temporary containers just in order to add items.

Regards,
 Alex



-----Original Message-----
From: qt-interest-bounces at trolltech.com [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Andreas Pakulat
Sent: Monday, July 12, 2010 3:15 AM
To: qt-interest at trolltech.com
Subject: Re: [Qt-interest] QtreeWidget::addTopLevelItem() very slow method

On 12.07.10 11:00:49, Roland Tollenaar wrote:
> It always strikes met that adding an item to a treewidget, even if the
> item already exists, is a very slow operation.
>
> Is there anyone who knows the technical reason for this and consequently
> whether (perhaps at the cost of some concession) this performance can be
> improved.
>
> PS the slowness is not directly noticable for small datasets but at 1000
> or more items to be added the issue becomes clearly evident.

Are you adding each item individually or all at once? Its not very
surprising that adding them individually causes performance problems as
each addition will cause the tree layout to change etc. Also for that many
items its usually better to write a custom model and use QtreeView, the
*widget versions goal is "ease of use" not performance. With a custom model
you could inform the view about the insertion of 1000 new items at once,
causing only 1 layout re-calculation.

Andreas

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