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

[Etienne Sandré-Chardonnal]

There are plenty of non-Qt stuff about this, for instance:

http://stackoverflow.com/questions/10078444/xcode-coordinates-for-ipad-retina-displays


2014-02-11 22:54 GMT+01:00 Etienne Sandré-Chardonnal <etienne.sandre at m4x.org
>:

> 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.
>
> Cheers,
>
> Etienne
>
>
> 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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>>
>>
>
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