Howdy Design gurus

In KDE4 kdelibs we had our own localization system which installed a set of 237 national flag icons for use in things like country pick lists. These were entirely non-standard and non-themed, they were about 21x14 pixels in size, installed in e.g. "/usr/share/locale/l10n/gb/flag.png", and had no api to make it easy for coders to find or use them. In KF5 we have dropped our localization system due it being non-standard, and as a consequence the flags have also been deprecated in kdelibs4support and will eventually disappear in 1-2 years time. This will leave a number of apps without a source of small flag icons.

Added to this is the need for some specialised apps like KGeography and Marble for larger country and state/provincial flags to display. KGeography ships a full set of higher resolution png flags and Marble ships a full set of SVG flags. Other non-KDE apps do the same. This duplication is obviously rather wasteful of space and bandwidth and it would be great if we had a single resource to install for these, especially one that can be shared between desktops.

The freedesktop.org Icon Naming standard provides us with an obvious replacement, it defines the "International" group for "Icons for international denominations such as flags" which gets installed in a directory called "intl" and are named "flag-xx" where "xx" is the ISO 3166 country code in lowercase. The disadvantage here is that very few (if any) icon sets ship these icons, adding them all would take quite some time and effort and space, the square icon sizes may not appropriate for some usecases compared to the variable width:height ratio of most flags, and not all apps will want to use a themed flag for their usecase.

One suggestion made in the past was to have a KFlags library that installs a full set of svg flags that apps can directly use, or can use an api to request png versions to fit a needed bounding box. Such a library may even be capable of theming the SVG flags on the fly. This idea never really went anywhere, partly due to anticipated SVG performance issues, but Marble's set of SVG flags would probably be a good starting point.

My current thoughts on a solution are to provide two options:
* Firstly have a KFlags Framework that contains the base set of svg flags that specialized apps could use directly, and that the icon designers could use to generate their icons. This could also include a default unthemed icon set auto-generated from the svg files to use as a default fall-back if the users chosen icon theme doesn't include flags.
* Secondly have the default Plasma icon set include the full set of themed flags at key resolutions, i.e. 21x21 suitable for combo-boxes, 32x32 for other uses, and a large size for other usecase. If this bloats the default icon set too large it could ship as a separate icon theme.

I'd be interested to hear your thoughts about where we should go with this, especially as I know little of the icon production process and the main solution would put a *lot* of work on the icon designers.

Hi, you are welcome to participate in the discussion:
https://phabricator.kde.org/T13722