Don't hard-depend on humanity-icon-theme

[Jeremy Bícha]

software-center depends on humanity-icon-theme which adds a few MB to the .iso size for flavors like Xubuntu or Ubuntu GNOME which ship a different theme by default. This is also an issue for Debian which packages software-center but not humanity-icon-theme yet.

softwarecenter/ui/gtk3/utils.py has this note
    # add the humanity icon theme to the iconpath, as not all icon
    # themes contain all the icons we need
    # this *shouldn't* lead to any performance regressions
    path = '/usr/share/icons/Humanity'

A quick grep shows at a minimum these hard-coded icons as well:
softwarecenter/ui/qml/SearchBox.qml: source: "file:///usr/share/icons/Humanity/actions/16/edit-find.svg"
softwarecenter/ui/qml/SearchBox.qml: source: "file:///usr/share/icons/Humanity/actions/16/edit-clear.svg"
softwarecenter/ui/qml/pkglist.py: path = "/usr/share/icons/Humanity/categories/32/applications-other.svg"

Those files should not be hard-coded as they are shipped by many icon themes such as gnome-icon-theme. Even the HighContrast theme which is included in Ubuntu by default ships those icons. I believe you are hurting accessibility by not allowing the HighContrast theme to provide those icons.

The problem with hard-coding an icon theme is that it is a hack, a workaround to improve things for one app but making things more difficult for app developers (since they'll have to figure out similar hacks...which will cause problems if they want their apps to work on other distros as well) and theme developers who have to be aware of these issues. If there are icons that need to be available for all themes, please ship them in /usr/share/icons/hicolor/ instead.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: software-center 5.6.0-0ubuntu4
ProcVersionSignature: Ubuntu 3.9.0-2.7-generic 3.9.3
Uname: Linux 3.9.0-2-generic x86_64
ApportVersion: 2.10.2-0ubuntu1
Architecture: amd64
Date: Sun Jun 2 11:11:51 2013
MarkForUpload: True
PackageArchitecture: all
SourcePackage: software-center
UpgradeStatus: Upgraded to saucy on 2013-05-07 (25 days ago)

[Kiwinote (kiwinote)]

just to clarify:
- we depend on the humanity-icon-theme. There are many icon themes that do not ship all the category (no longer relevant) and subcategory (still required) icons. This leads to empty / generic icons being displayed if humanity-icon-theme is not installed - this being a suboptimal experience -, and we have had bug reports about this. It is perhaps unfortunate that this requires a dependency on humanity-icon-theme, but I think it's justifiable.
- the humanity icon theme is added last, this means that the current icon theme (this can also be the high contrast icon theme) gets the first opportunity to supply all the icons, the humanity icon theme is used solely as a fallback.
- everything in softwarecenter/ui/qml was experimental. If I recall correctly at the time when that was written it was not known how to (or perhaps not even possible to) load icons from the icon theme or something of the likes.

[Jeremy Bícha (jbicha)]

Thanks, since the gnome-icon-theme doesn't provide the subcategory icons I reported a bug there.

[Matthew Paul Thomas (mpt)]

The category/subcategory icons are USC-specific, so I'd be surprised if gnome-icon-theme ever included them.

It might make more sense to move them inside the USC codebase, so USC can use them as a last-ditch fallback whenever the current theme chain doesn't provide them.