[Development] sizeHint for QAbstractScrollArea, especially item views

[jan-arve.saether at nokia.com]

Hi,
I agree that the current behavior is sometimes not optimal, but I'm not sure if this is such a good idea.

With regards to behavior it has some advantages, but I believe it also has some disadvantages.

And since in addition it might introduce a performance penalty I'm leaning towards that this is not a good idea.

I've made a comment on the patch in gerrit:

http://codereview.qt-project.org/#change,11763


Jan-Arve

From: development-bounces+jan-arve.saether=nokia.com at qt-project.org [mailto:development-bounces+jan-arve.saether=nokia.com at qt-project.org] On Behalf Of ext Christoph Schleifenbaum
Sent: 22. desember 2011 18:07
To: development at qt-project.org
Subject: [Development] sizeHint for QAbstractScrollArea, especially item views

Hi,

currently, item views do return a rather random size hint. Some at KDAB, including me, would love to see a size hint actually being related to the scroll area's content. For this, we thought of a method viewportSizeHint which returns the size of the viewport as if there would be no scroll bars required.

The most common use case for this is a list or a table of data in a window:

a) The ui designer doesn't need to set a custom size for the view, the size hint will make sure all data are visible

b) The amount of data might grow, in that case it might made sense to enlarge the view. Imagine three tree views below each other inside a scroll area. If the tree views would stay at their size, a scroll bar would appear in both the tree view and in the surrounding scroll area. This won't happen with a proper size hint combined with a size policy.

I'v attached a patch to the current qtbase.git. It does the described behaviour for QScrollArea and QTableView. Try running the example at examples/itemviews/spreadsheet to see what happens if you e.g. resize the columns in the table view.


Thoughts?


Cheers,
Christoph


--
Christoph Schleifenbaum | christoph.schleifenbaum at kdab.com | Software Engineer
Klarälvdalens Datakonsult AB, a KDAB Group company
Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
KDAB - Qt Experts - Platform-independent software solutions
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