[Interest] iPad mini Retina 2048 x 1536 display resolution issue with QtQuick apps

Etienne Sandré-Chardonnal etienne.sandre at m4x.org
Tue Feb 11 22:54:05 CET 2014

In fact, by default iOs apps are run in a compatibility mode with the lower
non-retina resolution. The device, though, draws fonts and primitives in
high res, but the app has a 1024x768 logical screen.
There is a native high res mode where you directly adress the 2048x1536
pixels, but it requires to be switched on. I do not know if it's available
in QtQuick, but I would guess it's not.



2014-02-11 22:49 GMT+01:00 VStevenP <vstevenpavao at yahoo.com>:

> Hi Etienne,
> That makes good sense to me.  I did not try drawing such an image in such
> a rectangle, but I will try.
> - VStevenP
>   ------------------------------
>  *From:* Etienne Sandré-Chardonnal <etienne.sandre at m4x.org>
> *To:* VStevenP <vstevenpavao at yahoo.com>
> *Sent:* Tuesday, February 11, 2014 4:41 PM
> *Subject:* Re: [Interest] iPad mini Retina 2048 x 1536 display resolution
> issue with QtQuick apps
> Hi, I believe that Retina displays, for compatibility with non-retina,
> expose the same screen resolution (1024x768). This means that every
> adressing of pixel coordinates should be made in that resolution. The
> double resolution is only used internally by the device for rendering
> fonts, textures, etc... This way, you write the exact same UI for newer and
> older devices.
> Did you try drawing a 2048x1536 images in a 1024x768 top-level rectangle?
> Cheers,
> Etienne
> 2014-02-11 22:28 GMT+01:00 VStevenP <vstevenpavao at yahoo.com>:
> I just got an iPad mini retina 2048 x 1536 for developing QtQuick apps.
> If I set the width and height of my top-level QML Rectangle to 2048 x
> 1536, it overflows the screen by 2x in each dimension.  So it's seems like
> there's a mistaken doubling of pixel dimensions for rendering for this iPad
> model.
> I tested this iPad with its built-in Safari to see that some larger google
> images were rendering at the proper pixel dimensions, and they are
> rendering correctly.  2048 x 1536 images were not overflowing the display
> at 2x.
> Any one else observe this?   I didn't see it in JIRA.  I will enter a bug
> if that's the right thing to do.  Maybe Qt5 needs to do something special
> to address the iPad mini Retina as 2048x 1536.
> - VStevenP
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