[Development] Bringing Qt's high-dpi support to more platforms

Knoll Lars Lars.Knoll at digia.com
Tue May 27 08:23:25 CEST 2014

On 26/05/14 23:58, "Portale Alessandro" <Alessandro.Portale at digia.com>

>> From: Sorvig Morten [Morten.Sorvig at digia.com]
>> Sent: Monday, May 26, 2014 14:03
>> On 23 May 2014, at 18:30, Thiago Macieira <thiago.macieira at intel.com>
>> > Em sex 23 maio 2014, às 07:20:42, Sorvig Morten escreveu:
>> >> Adding support to QtWayland looks like a win to me. Do we want to add
>> >> platform-indepent support to Qt?
>> >
>> > I think my question is: why wouldn't we?
>> The platform independent patch adds coordinate system conversion calls
>>to most QWindowSystemInterface::handle* functions and some QWindow
>>functions. These have to be maintained by everyone that works on that
>>code. Its not that much work but still yet another thing to be aware of.
>>So I would like to see consensus on “Yes, this is worth maintaining”.
>> Morten
>I believe it is definitely worth maintaining! And I believe Qt
>desperately needs it, since high-dpi is a very common case on Mobile
>devices and it is becoming common on non-Apple Desktop. (Is your current
>device pixel ratio really just 1? http://www.devicepixelratio.com/ )
>Just to make an example, Qt Creator looks bad on Windows or Linux with
>200% "font scaling"
>https://bugreports.qt-project.org/browse/QTCREATORBUG-11179 while it is
>in much better shape on Mac+Retina . The devicePixelRatio scaling feature
>in Qt on all platforms would be a sane solution for high-dpi Qt Creator,
>and most likely for other applications as-well.
>The second part of your proposed implementation, the settable
>QT_HIGHDPI_SCALE_FACTOR, makes it very flexible. That way the application
>author can decide when to turn off devicePixelRatio scaling on Apple
>devices or turn it on on others. I am looking forward for Qt 5.4, the
>high-dpi release :)

Yes, let’s add it.  I’ve been struggling enough trying to make Creator
usable when running Linux on a Retina Mac Book, and without some high DPI
support Qt apps won’t ever work decently.


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