[Development] Speaking about Icons.

Olivier Goffart olivier at woboq.com
Mon May 14 17:48:07 CEST 2012

On Monday 14 May 2012 17:05:46 Corentin Jabot wrote:
> Hi.
> The methods setWindowIcon are not yet implemented in Qt5.
> That concerns QWindow, QWidget and QApplication.
> I guess the reason for that is that QIcon is part of QtWidget and not QtGui.
> QIcon seems not movable, it use a lot of QWidget styles stuffs
> For that reason the not-implemented QWindow::setWindowIcon ( as well
> as QPlatformWindow::setWindowIcon) take a QImage as parameter.
> So it will only use one image for all sizes the system required, and
> icon will certainly look ugly as they are upscale/downscale too much.
> For that reason I think we need something like a QWindowIcon or a
> QApplicationIcon to stores a different QImage for different size.
> It's a sub-optimal solution, because the setWindowIcon will have
> different signature in QtGui and QtWidget.
> So ..
> Can you think of something better ?
> What should be the features & api of QWindow Icon.  ?
> Is it still time for this change in 5.0 ? or should we wait 5.1 ?  I
> think in both case, we have to start using it privately if we want
> keep QWidget::setWindowIcon working.
> This change is mostly required for linux, since windows will use the
> icon provided by the RC file and Mac using the one declared by
> Info.plist.
> I worked on a small ugly change about this issue
> https://codereview.qt-project.org/#change,25373 , just to see what
> would need to be done.

This has already been discussed there:


 - QIcon is the exact candidate for that.

 - There is nothing that is tying QIcon to QtWidget, it really belongs to 

 - As for QIcon::fromTheme, some API could be added to the Theme QPA plugin, 
and its implementation moved there.

 (- But QIcon only make sens on Desktop so Nokia has nothing to care)

So I think QIcon should be moved to QtGui.

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