[Development] Revisiting high-DPI configuration options

[ekke]

Am 22.06.16 um 14:46 schrieb Morten Sorvig:
>> On 22 Jun 2016, at 10:30, Michael Zanetti <michael.zanetti at canonical.com> wrote:
>>
>>
>>
>> On 20.06.2016 15:00, Morten Sorvig wrote:
>>> Another reason to not spend time on it would be that integer is, or is going
>>> to be, the dominating use case. Wayland and Apple is integer, so are most of
>>> the Android device categories. For Windows and desktop in general there are
>>> currently lots of fractional hardware and configurations.
>> I don't think this is true. From all the devices (phones/tablets) we
>> support Ubuntu on, none is a full integer multiplier. I really don't see
>> how it is going to fly if only full integers are supported. After all,
>> all the Ubuntu Devices are actually based on Android hardware, so surely
>> there the same issue would happen, no?
>>
> What I have for Android devices are tables like this: (there are various
> sources, see below)
>
> 0.75 - ldpi
> 1.0 - dpi
> 1.5 - hdpi
> 2.0 - xhdpi
> 3.0 - xxhdpi
> 4.0 - xxxhdpi
>
> The factor here is DisplayMetrics.density. This suggests integer factors, or
> at least a convergence towards integer factors if we allow that new Android
> devices are xhdpi or better.
my android device  reports 3.5 for

qApp->primaryScreen()->devicePixelRatio()


Does this mean Qt is using 4.0 and not 3.5 as scale factor ?
Images are correctly used from @4

ekke
> It think what is happening is that the hardware may be non-integer, but then
> Android maps that to a device class with a fixed scale factor. We can use that
> scale factor in Qt - any error introduced by it (if the hardware is some fraction
> between classes) will be matched by the native UI.
>
> If Qt applications are going to see fractional factors on Ubuntu then that’s
> a point in favor of making Qt work better in that configuration.
>
> Morten
>
> http://stackoverflow.com/questions/3166501/getting-the-screen-density-programmatically-in-android
> https://groups.google.com/forum/#!msg/android-developers/g56jV0Hora0/9d8p8QJg1ksJ
>

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