Icons installed by apps

[Jaroslaw Staniek]

On 23 September 2015 at 09:31, Harald Sitter <sitter at kde.org> wrote:
>>
>> You mean if {appname} and {appname}-foo doesn't right?
>>
>> the XDG icon spec has some kind of inheritance built into the name so
>>
>> someaction.png
>>
>> is chosen if you don't have
>>
>> someaction-veryspecific.png
>>
>> So you may want to use another way of prefixing that doesn't mess with that
>> like and _ or just nothing at all.
>
> I seem to recall this actually coming up in Randa. IIRC the icon theme
> artists would very much prefer if custom icons you want to provide are
> using the specification system outlined by the theme spec and are
> installed to hicolor. Which then behaves exactly as Albert outlined,
> when QIcon resolves for "icon-specific-very" the following order
> applies:
>
> icon.png < icon-specific.png < icon-specific-very.png
>
> So you could have places/database-implode-kexi.png which makes the
> icon you installed themable as database-implode.png, but at the same
> time makes it non-conflicting with other applications that may want to
> install database-implode to hicolor.
>
> On a related note, since it came up in the original mail: yes, breeze
> is a default fallback in kf5 applications *as long as the
> frameworkintegration platformtheme is installed and loaded* [1].
> Additionally breeze currently inherits from oxygen, through the theme
> config itself, this might go away at some point though. So right now
> the effective resolution order is userTheme > breeze > (oxygen) >
> hicolor.
>

Thanks for this info Harald and Albert!

Some background about motivation.
My idea is to default to breeze on non-Plasma platform and on without
the frameworkintegration platformtheme.
And avoid surprising on Windows and Mac. Silently hoping that some
reasonable habits could help to convince someone to use KF5 for
general cross platform apps developments.

Related thing: I don't expect new app-specific icons/emblems will be
prepared for oxygen or various themes.
Surely it's better for _truly_ 3rd-party plugins (that I expect to
appear more one day) to know the theme recommendations and defaults --
I see consistency as more valuable than freedom of theming for complex
apps.
For some time I was also wondering that documentation's screenshots
have to pick one theme anyway, so better not to confuse users...

Another thing: should I wonder that in my strace logs, for icons that
exist for hicolor only, the "userTheme > breeze > (oxygen) > hicolor"
scheme results in 4 * 'dozens of lookups'? Because of the fallback
strategies this cannot be cached I guess, only actual content is
cached. A simple filesystem stat() may be cheap but there are lots of
it. For example a custom file that sits in hicolor only when I have
breeze theme selected calls stat() 515 times. (there's no the
'userTheme' step). To get just a simple and single 4KiB icon, n*515
memory (re)allocations are needed.

As I mentioned in this thread quite a few KDE apps use .qrc for custom
icons but no idea if this intentional or rather a convenient approach
well supported by Qt Designer and .ui files.

Thirdly, I suppose it's possible to indicate in the code that I am
looking for a "place" icon group for example. That would slash the
number of lookups and also limit conflicts. Maybe that would be a
violation of behaviour required by fd.o? No idea.

My fresh test results in one observation, network-server-database-kexi
which causes the above 515 stat()'s
sits in share/icons/hicolor/22x22/places/network-server-database-kexi.svg.
It is not found, instead
share/icons/breeze/places/22/network-server-database.svg is returned.
This is maybe because network-server-database is a prefix equal to an
existing icon? Why is it of higher priority than the exact match?
No change after removing of the icon cache. To make sure what happens
I'd try to use '_' separators as Albert suggests.

I appreciate any comments.

-- 
regards, Jaroslaw Staniek

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: http://www.linkedin.com/in/jstaniek