[Development] Updated high-DPI support for Qt 5.14

Elvis Stansvik elvstone at gmail.com
Fri Oct 4 18:06:32 CEST 2019


Den fre 4 okt. 2019 12:39Morten Sørvig <Morten.Sorvig at qt.io> skrev:

>
>
> > On 3 Oct 2019, at 09:44, Mark De Wit <mark.dewit at iesve.com> wrote:
> >
> > Is there a chance that the high-dpi work will fix the dpi-awareness of
> the Fusion theme as reported in
> https://bugreports.qt.io/browse/QTBUG-74100 ?
>
> Yes, looks like an easy fix:
> https://codereview.qt-project.org/c/qt/qtbase/+/276261
>
> >
> > Last time I checked there was a fair amount of drawing code that didn't
> check what screen a widget was on, and hence used "global" scaling (if any).
>
> QPainter picks up the correct factor via the paint device, so the
> draw-on-widget case should work without checking the screen. But there
> might be other cases such as painting on a intermediate pixmap which needs
> fixing.
>

I also think there might be some wonkiness in generation of pixmaps from
SVG icons specified via theme lookup.

I think it was due to the icon theme engine possibly not using the correct
overload... Something like that.. Don't have the bug number (on my phone on
a train atm) and it may already have been fixed.

We have some manual workaround code for that issue in our app. Been meaning
to look into what the status in recent Qt is (we unfortunately must work
well with the 5.9 in Ubuntu 18.04 until 20.04 is out).

Elvis


> Morten
>
> >
> > Mark
> >
> >> -----Original Message-----
> >> From: Development <development-bounces at qt-project.org> On Behalf Of
> >> Christoph Cullmann
> >> Sent: 01 October 2019 22:19
> >> To: development at qt-project.org
> >> Subject: Re: [Development] Updated high-DPI support for Qt 5.14
> >>
> >> Hi,
> >>
> >> actually, unrelated to how one can configure the stuff, at the moment,
> I see
> >> still a lot of Qt internal rendering artifacts for fractional scaling.
> >>
> >> See https://bugreports.qt.io/browse/QTBUG-66036
> >>
> >> For some I made now hacky workarounds in KTextEditor, see
> >> https://bugs.kde.org/show_bug.cgi?id=390451
> >>
> >> Some still remain for factors like 1.1 and text selections...
> >>
> >> And one should think about if it is really a good idea to accept
> factors like 1.1
> >> and not round them to some at least 1 / 2^x factor that doesn't lead to
> >> interesting accumulating rounding errors. (in addition to the opt-out of
> >> fractional scaling at all)
> >>
> >> Greetings
> >> Christoph
> >>
> >> --
> >> Ignorance is bliss...
> >> https://cullmann.io | https://kate-editor.org
> >> _______________________________________________
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> >> Development at qt-project.org
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