QIcon::fromTheme(xxx, someFallback)

[David Faure]

On Wednesday 09 September 2015 10:24:23 Olivier Goffart wrote:
> 
> I tried to optimize it by 'caching' the isNull value in QIconPrivate.
> 
> But then the test failed:
> http://code.woboq.org/qt5/qtbase/tests/auto/gui/image/qicon/tst_qicon.cpp.html#633
> In that test, the "address-book-new" was looked before and cached, and then we 
> expect that looking it up again after changing the theme name changes.
> So cahcing the value of isNull would make the test fail, because it would be 
> cached as not null.  Yes, the behaviour is that when changing the themeName, 
> existing QIcon will be re-looked-up next time we try to render them.

One solution would be a "change counter" in the icon engine, incremented
when changing themes. In QIcon, comparing a local number with that change counter,
and skipping the cache if they don't match. But of course this means one more int
per icon, so I don't know if it's a good idea. 

But yeah your isNull implementation looks fast enough; I was afraid it would be a call
to availableSizes() like fromTheme was doing.

-- 
David Faure, faure at kde.org, http://www.davidfaure.fr
Working on KDE Frameworks 5