> On 18 Feb 2016, at 12:35, Nikita Krupenko <krne...@gmail.com> wrote:
>
> 2016-02-18 12:50 GMT+02:00 Hausmann Simon <simon.hausm...@theqtcompany.com>:
>> (1) In order to make it really easy to scale "logical" pixels without having
>> to introduce your own context property or factor in a .qml file that you
>> multiply everywhere, we could turn the regular "pixels" in QtQuick into
>> truly logical pixels that scale with an application wide (or window wide)
>> factor. So Image { width: 100 ... } will scale automatically from 100
>> logical pixels to maybe 200 physical pixels on a x2 display. This assumes
>> the availability of API to change this mapping.
>>
>> (2) In the events where you still _want_ to use physical pixels, you could
>> use "px" units.
>>
>> So at first nothing would change for app developers at all because we map
>> logical pixels to physical pixels. But
>> if you'd like to, you could opt into changing this mapping and having a
>> relatively easy fallback to physical pixels using for example the "px" unit.
>> We might as well offer the other physical units anyway, that probably causes
>> little to no harm.
>
> Isn't (1) already done with Qt::AA_EnableHighDpiScaling? Though
> disabling this feature for some items would be useful, like for
> Canvas, which is broken now with this scaling.
This is indeed what is done for that flag and on OS X and iOS. In that
sense logical pixels are already supported.
“px” could be added, but what are the use cases? You almost never want to
have small content on high-DPI display. I see doing custom scaling in the
application as a possible one.
As a minor platform note, “px” would not be guaranteed to be physical pixels
on Apple operating systems. There can be further resolution virtualization,
for example when setting a scaled resolution for the display.
Morten
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