[Interest] High DPI support in QT (Windows)

Pavlo Dyachenko upavlo at gmail.com
Mon Sep 21 19:52:39 CEST 2015

Yes, it seems that there are some minor improvements,
however QT_SCALE_FACTOR variable still only supports numeric values.

On 21 September 2015 at 16:36, Adam Light <aclight at gmail.com> wrote:

> 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
> documentation.
> Adam
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