Re: GSoC Project Proposal: Make High-DPI awesome
- Date: Wed, 22 Mar 2017 12:50:16 +0100
- From: lukas@xxxxxxxxxxxxxx
- Subject: Re: GSoC Project Proposal: Make High-DPI awesome
first of all - thanks to all for reading my proposal and your
I will apply this patch and test if it improves the situation. But as
far as I see now, this only changes the positioning of windows.
There seem to be other rendering issues in a variety of applications,
mostly in kdegraphics related ones:
- gwenview - https://bugs.kde.org/show_bug.cgi?id=373178 - Blurry
scaling on HiDPI
- okular - https://bugs.kde.org/show_bug.cgi?id=362856 - Wrong render
resolution, possibly caused by Plasma 5 "Scale Display"
- krita - https://bugs.kde.org/show_bug.cgi?id=360541 - HiDPI option in
Qt also scales the canvas widget
But also similar rendering issues exist in konsole, systemsettings and
plasma (e.g. on the logout/shutdown and startup screen).
Some of these seem to be caused by QPixmaps with no devicePixelRatio
set, resulting in blurred or wrongly scaled images. I don't think there
is a Qt- or KDE-wide approach that could simply fix this. Therefore my
proposal to look into every problematic application and fix the issues
there. I have a partly working patch for gwenview which does this
(changes were the mentioned devicePixelRatios and taking those values
into account in the paint method).
On 2017-03-22 08:03, Thiago Macieira wrote:
Em terça-feira, 21 de março de 2017, às 03:51:16 PDT, Stefan Derkits
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
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
to create a display (for example) 640x480, it does that in
pixels, so it actually creates an area 1280x960, which is 4x bigger
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
Note that fractional scaling is not supported by Qt. You can do 1x or
E.g. Java FX (starting from Java 9) Applications check the GDK_SCALE
environment variable, which by default isn't set. Also some
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
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
Not supported by Qt. Like I said, you can have 1 or 2, but not
There's a patch for Qt by Morten that enables this, but you'll see
problems because of rounding errors. So, don't.
Supporting different scaling depending on monitors is possible with X,
recommended. You're much better off having a single scaling factor for
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?
Set GDK_SCALE and CLUTTER_SCALE, that's all. I don't know which of
controls Firefox and Chrome, but they are properly scaled up in my
I run 3200x1800 in my laptop and 3840x2160 in the external monitor.