High DPI issues

[Teo Mrnjavac]

On Monday, May 26, 2014 17:47:35 Teo Mrnjavac wrote:
> On Tuesday, May 20, 2014 15:16:25 Teo Mrnjavac wrote:
> > On Tuesday, May 20, 2014 14:55:16 David Edmundson wrote:
> > > On Tue, May 20, 2014 at 2:28 PM, Teo Mrnjavac <teo at kde.org> wrote:
> > > > Another important issue is that currently the only tested and nicely
> > > > working values for QT_HIGHDPI_SCALE_FACTOR are 1.0 and 2.0, i.e. Mac
> > > > OS
> > > > style scaling.
> > > 
> > > I can't imagine it being too big a problem; things only look bad once
> > > they're past a certain point.
> > > 
> > > > produce decent results and minimize glitches, but the only way to be
> > > > sure
> > > > of that is trying it out. I'll try to give his branch a spin when I
> > > > get
> > > > the chance.
> > > 
> > > Please do, and report back.
> > 
> > Will do.
> 
> High DPI status update, part 2.
> 
> So I've managed to build Morten's highdpi branch [1] and (most of) the
> kdesrc- build roster on top of it. Right now the highdpi branch tracks
> stable. As hinted last week, this branch scales up all UI elements by a
> scaling factor. On OSX this scaling factor is 1.0 or 2.0, in line with
> Apple's retina scaling policy, but on X11 it doesn't have to be an integer.
> Also on X11 there is no code that tries to guess this scaling factor,
> relying instead on an environment variable QT_HIGHDPI_SCALE_FACTOR.
> 
> I've made some screenshots of Kate with different values of
> QT_HIGHDPI_SCALE_FACTOR. All of them are with kwin 4 and unless otherwise
> noted, the style is Fusion.
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopIo2083.png
> QT_HIGHDPI_SCALE_FACTOR not set.
> Font size in pixels is big because the fonts DPI is from the Xft.dpi setting
> which in turn comes from my Nvidia driver. The window opens up way too
> small for my screen.
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopni2083.png
> QT_HIGHDPI_SCALE_FACTOR=1.0
> It looks like the scale factor overrides the Xft DPI setting.
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopaQ2083.png
> QT_HIGHDPI_SCALE_FACTOR=1.5
> Decent overall widget geometry, window size also good automatically. Bad
> pixmaps, font kerning issues to be fixed in Qt.
> 
> http://wstaw.org/m/2014/05/26/plasma-desktoppN2083.png
> QT_HIGHDPI_SCALE_FACTOR=1.75
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopLe2083.png
> QT_HIGHDPI_SCALE_FACTOR=2.0
> Pixmaps still rough, fonts look better. This is arguably the right scale
> factor for my 215ppi panel, and the overall result is visually nice.
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopTf2083.png
> QT_HIGHDPI_SCALE_FACTOR=3.0
> 
> http://wstaw.org/m/2014/05/26/plasma-desktopCs2083.png
> QT_HIGHDPI_SCALE_FACTOR=2.0
> With Oxygen style.
> 
> Feel free to let me know if you can think of ways to break it, I can try and
> report back with screenshots.
> 
> As for generating the QT_HIGHDPI_SCALE_FACTOR, we can have some heuristics
> based on Xft DPI (if set), which could then be overridden in the Fonts KCM
> or some other KCM. Multiples of .25 or even .5 would probably be just fine,
> so if we scale pixmaps to increments of .5 and if the font rendering issues
> are fixed upstream, this could work nicely.
> 
> I'm still curious what happens in Plasma with this scaling factor, but
> unfortunately plasma-framework didn't build for me with the highdpi branch.
> I'll investigate and report back if there's breakage.
> 
> [1] https://github.com/msorvig/qt5-qtbase-highdpi
> 
> Cheers,

Something I forgot yesterday: this stuff is also on Gerrit [1] as of a few 
days ago.

[1] https://codereview.qt-project.org/#change,86107

Cheers,
-- 
Teo Mrnjavac
http://teom.org | teo at kde.org