[Interest] Qt5 and "global" configuration

[Thiago Macieira]

On Thursday 13 November 2014 18:52:45 Stanislav Baiduzhyi wrote:
> On Thursday 13 November 2014 09:25:43 Thiago Macieira wrote:
> > > That can be extremely problematic on desktops without any kind of UI or
> > > less supported UI. Think of TWM, IceWM, some rare desktops like now
> > > perished RazorQt and stuff like that. Or adding second user on your main
> > > system but not logging in for the first time to allow KDE or gnome to
> > > create any configuration, but just launching Qt apps with kdesu or sudo.
> > > In addition, all of that can go though vnc to the display with ppi
> > > resolution very far from one the app is launched on. In those cases
> > > having normal
> > > configurations hierarchy (like read app settings, fallback to ~/.config,
> > > fallback to /etc) would be extremely helpful. And that is one of the
> > > reasons why using Qt4 apps in all of those cases I listed above is way
> > > more
> > > convenient than using Qt5 apps.
> > 
> > Qt is not a desktop. I don't like the idea of qtconfig because it's not
> > Qt's purpose to do that. It's the desktop's.
> 
> Which means that we should not use Qt5 apps on less supported desktop
> environments and we should not use Qt5 apps launched under another user with
> empty home folder? 

No, it means Qt 5 needs to support those desktops too, as much as possible. 
Note that all the Qt-based desktops should provide the theme plugin by 
themselves.

As for an empty $HOME, it means no desktop, so the Fusion style is just fine.

> Which effectively means that target audience of Qt5 is
> much smaller than target audience of Qt4?

No.

> If there is no qtconfig and configuration files hierarchy, there should be
> another way of doing the same things. In my opinion, following list would
> solve the majority of issues:
> 
> 1. Propose default font size in pt for fontconfig, and support that
> parameter in Qt.

Agreed.

> 2. Read 'dpi' config value from fontconfig.

Disagreed. The DPI value comes from the windowing system, not from fontconfig.

> 3. Propose (or use if already exists) some XDG variable or something like
> that to determine if desktop is black-on-white or white-on-black, and add
> support for those 2 basic setups.

You're proposing an XDG widget style/theme configuration. It's required, but it 
won't happen. Moreover, I don't think it can happen, since the style is more 
than the colours and font sizes. It's also about what the widgets look like 
and how they behave. Those aren't configuration files, they are *code*.

It gets worse with Wayland because now applications need to draw the window 
decorations too. Unless ALL the toolkits have each a plugin for the same 
themes, the window decorations will look different.

> That's all that needed to make Qt5 look bearable on unconfigured/unsupported
> desktop.

Unconfigured is out of scope. Unsupported is solved by making it supported.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center