[Interest] SVG is loaded with invalid dimensions on some machines

[Elvis Stansvik]

Den tors 18 apr. 2024 17:11Alexander Dyagilev <alervdvcw at gmail.com> skrev:

> Well, I was able to reproduce the issue.
> 1. Launch app.
> 2. Change system zoom settings from 100% to 125%.
> 3. Done. The issue is here. After restarting app - issue is not
> reproduced.
> So, just a guess, on 2-monitor system this zoom settings changes at
> runtime (maybe app is started initially on some monitor and then moves to
> another one with different zoom setting).
> *Question is*: is it possible to disable this auto-zoom thing for a
> particular image or at least globally?
>

I dont think so. You need to query the device pixel ratio of the screen
your widget is currently displayed on and re-rasterize your SVG to the
appropriate pixel dimensions. You also need to listen for events indicating
a change in device pixel ratio (i.e. user changing their system
preferences) and indicating your widget was moved to another monitor where
the ratio is different, and do the same if that happens. At least that's my
understanding.

We do the same in our app in places where we paint in physical pixels and i
think this is par for the course for DPI-aware Qt applications.

I could be wrong.

Elvis


> On Thu, Apr 18, 2024 at 9:52 PM Alexander Dyagilev <alervdvcw at gmail.com>
> wrote:
>
>> Hello,
>>
>> The user with the issue has two monitors connected to his PC. *Weird
>> thing* is that SVG is loaded properly on one monitor (2K) and improperly
>> on another one (FullHD). How can this be? Only Qt authors can probably shed
>> some light on this issue :)
>>
>>
>> On Thu, Apr 18, 2024 at 11:24 AM Alexander Dyagilev <alervdvcw at gmail.com>
>> wrote:
>>
>>> Image as it's displayed on the user's machine:
>>>
>>> [image: image.png]
>>>
>>>
>>> On Thu, Apr 18, 2024 at 11:21 AM Alexander Dyagilev <alervdvcw at gmail.com>
>>> wrote:
>>>
>>>> I forgot to mention that this happens at least with Qt 6.4.3 and 6.6.2
>>>> (or 6.6.3 I don't remember exactly). We use this code to load the image:
>>>>
>>>> import QtQuick 2.12
>>>>
>>>> Image
>>>> {
>>>>     property double zoom: 1.0
>>>>
>>>>     readonly property int preferredWidth: sameHiddenImg.implicitWidth *
>>>> zoom
>>>>     readonly property int preferredHeight: sameHiddenImg.implicitHeight
>>>> * zoom
>>>>
>>>>     // it works buggy under e.g. Retina displays without this
>>>>     width: preferredWidth
>>>>     height: preferredHeight
>>>>
>>>>     // it works buggy under e.g. Retina displays without this
>>>>     sourceSize: Qt.size(width, height)
>>>>
>>>>     Image
>>>>     {
>>>>         id: sameHiddenImg
>>>>         visible: false
>>>>         source: parent.source
>>>>     }
>>>> }
>>>>
>>>> So, valid values for preferredWidth and preferredHeight are 93 and 456.
>>>> But for some rare users they are 116 and 570 accordingly.
>>>>
>>>> On Thu, Apr 18, 2024 at 11:16 AM Alexander Dyagilev <
>>>> alervdvcw at gmail.com> wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> A few of our users have issues with UI rendering. We SVG sprite to
>>>>> display some elements of our UI. This SVG has a size specified in it
>>>>> (93x456). And of course we rely on it. The issue is that sometimes it's
>>>>> loaded with 116x570 size due to some unknown reason. So it's like a
>>>>> different image and we can't use such a sprite properly anymore.
>>>>>
>>>>> What can be the cause of that? I've attached this sprite image.
>>>>>
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