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Re: GSoC Project Proposal: Make High-DPI awesome




Em terça-feira, 21 de março de 2017, às 03:51:16 PDT, Stefan Derkits escreveu:
> On 2017-03-21 00:34, Lukas Hetzenecker wrote:
> > I’m looking also forward to any feedback you have about this proposal.
> 
> I would really love to see the results of such a project. As I wrote you
> in a personal mail, for me HiDpi works already mostly well,but some
> Applications still have problems with it.

I have only one application left with problems and that's krdc: when I tell it 
to create a display (for example) 640x480, it does that in device-independent 
pixels, so it actually creates an area 1280x960, which is 4x bigger than the 
display it is going to get from the network and embed from vncviewer.

All other applications are working fine now that I submitted this Qt patch: 
https://codereview.qt-project.org/188493

Note that fractional scaling is not supported by Qt. You can do 1x or 2x, but 
nothing in-between.

> E.g. Java FX (starting from Java 9) Applications check the GDK_SCALE
> environment variable, which by default isn't set. Also some applications
> have in my experience problems if QT_SCREEN_SCALE_FACTORS is set (e.g.
> VLC & JetBrains Toolbox)

VirtualBox has the same problem I described for krdc above. I didn't see a 
problem with VLC, but I suspect it would be the exact same issue.

> I especially like the following parts of your proposal:
> * Polishing user interface for HiDPI settings. Extend it, so it allows
>   different scale factors for multiple screens. [my external 27" 4K
> Monitor could need a smaller scaling factor than my 15" 4K Laptop Screen]

Not supported by Qt. Like I said, you can have 1 or 2, but not fractional. 
There's a patch for Qt by Morten that enables this, but you'll see plenty of 
problems because of rounding errors. So, don't.

Supporting different scaling depending on monitors is possible with X, but not 
recommended. You're much better off having a single scaling factor for all 
monitors. Or switch to Wayland.

> * If possible, try to also force other applications to use configured
>   settings when starting a KDE workspace (Firefox? Google Chrome? GTK?
>   Java?)

Set GDK_SCALE and CLUTTER_SCALE, that's all. I don't know which of those 
controls Firefox and Chrome, but they are properly scaled up in my system.

I run 3200x1800 in my laptop and 3840x2160 in the external monitor.
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center