[Interest] High DPI support in QT (Windows)

Adam Light aclight at gmail.com
Mon Sep 21 17:36:47 CEST 2015

On Fri, Sep 18, 2015 at 1:38 AM, Pavlo Dyachenko <upavlo at gmail.com> wrote:

> Hi QT team, I posted a question on the forum about high DPI support but
> then was recommended this mailing list instead:
> According to documentation here http://doc.qt.io/qt-5/highdpi.html QT
> 5.4+ introduces high DPI support. However, either I’m missing something
> fundamental or the current support is still in very early stages. I’m
> writing a brand new application so I have a chance to do it right from the
> ground up. I understand that I would have to use layouts instead of fixed
> positioning etc, but there always going to be cases in which I would have
> to specify, for example a minimum/maximum size of a control. I can specify
> them in the editor, but these are device pixels. So if I change my Windows
> settings to use 150% DPI then min/max values in the editor would be too
> small. Of course I can obtain that ratio and adjust all the required values
> in code, but then what kind of high DPI support does QT give for me if I
> have to do everything by hand? I mean how is it different to pre QT 5.4?
> Then an interesting one is QT_DEVICE_PIXEL_RATIO environment variable. It
> does exactly what I need, it multiplies all pixels set in editor by a
> factor. But why is it an environment variable and not a per application
> setting? Why does it only support integer values of 2, 3 etc, since we know
> that Windows has settings like 125, 150% etc. and why couldn’t it
> automatically read the Windows setting and set itself to that value?
Though I have not yet tried it, my understanding is that in Qt 5.6, the
support for HiDPI has been improved. See
https://doc-snapshots.qt.io/qt5-5.6/highdpi.html for the most recent

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