[Interest] application appearance changing when laptop goes in saving energy mode

[maitai]

Hello,

Still searching to fix that one.

I can now reproduce it at leasure: If I connect my laptop to an external 
monitor, launch the application, then unplug the external monitor and 
hover the mouse on the windows bar to make it appear (autohide is 
activated), my application AND QtCreator changes font, palette and 
style.

Then only way to get normal look back is to restart application. 
Reloading style, stylesheet, palette and font at application level does 
not fix existing widgets once they are corrupted.

I cannot find what trigger this, nor at qApp's event level or at 
QMainWindow level or at widget's level.

I am using qt 5.5.1 on windows 10. It does not seem to occur on Windows 
7 as far as I can tell.

I have users complaining about that too so it is not just me ;)

Any idea how to catch what is causing that and avoid it? Since it occurs 
also in QtCreator maybe I should open a bug report...

Thanks
Philippe Lelong


Le 09-11-2015 16:45, maitai a écrit :
> Thanks Robert for your reply,
> 
> In fact I succeeded to reproduce partly the problem. I have a laptop
> with 2 graphic cards, switchable. Whenever the PC goes in power-saving
> mode, it switches to the intel one. When this happens, my menubar
> (regular QMenuBar) is changing font and becomes ugly, and the only way
> to get it back to normal is to restart the application. It seems to
> happen also from time to time if I switch from external monitor to
> laptop monitor.
> 
> This app is not using opengl, it's just a plain QWidget app.
> 
> No signal or event as far as I can see is triggered when this happens,
> just a paintEvent it seems.
> 
> The funny thing is that even QtCreator is impacted by that... It also
> changes font or style.
> 
> Any clue on what is going on there?
> 
> Thanks
> Philippe Lelong
> 
> Le 09-11-2015 12:03, Robert Iakobashvili a écrit :
>> On Mon, Nov 9, 2015 at 7:54 AM, maitai <maitai at virtual-winds.org> 
>> wrote:
>>> 
>>> Hello
>>> 
>>> On Windows, some users are reporting that the application style 
>>> (font? palette?) is changing when laptop goes in energy saving mode, 
>>> and becomes more or less unreadable (white font on white background, 
>>> etc). I have seen that myself also a couple of times but I'm unable 
>>> to reproduce it.
>>> 
>>> When it occurs, putting the laptop back on power does not fix 
>>> anything, and the only way to get back the proper appearance is to 
>>> restart the application. If you start the application when in battery 
>>> saving mode, no problem. The application is widget-based 
>>> (QMainWindow, QGraphicalScene, QMenubar, etc), Qt is 5.5.1 but that 
>>> was reported also with previous Qt versions.
>>> 
>>> As I said this occurs only for a few users, and I cannot reproduce 
>>> it. Maybe it's connected with the laptop changing GPU, I don't know.
>>> 
>>> Does anyone knows what could possibly trigger this, and if I can 
>>> catch it somehow either to avoid it or reload style/palette/font/etc 
>>> when it occurs?
>>> 
>>> Thanks
>>> Philippe Lelong
>> 
>> 
>> Hi,
>> 
>> With which options Qt was configured and built?
>> 
>> Any plugins your software is using?
>> 
>> Is it correlating with any particular Windows versions
>> like on Windows-10 or 8.1?
>> 
>> That sounds like an aggressive memory optimization by OS.
>> Locking in memory sometimes could help against.
>> 
>> There is a Qt signal
>> 
>> QGuiApplication::on_applicationStateChanged(Qt::ApplicationState 
>> state);
>> 
>> and using it on Android.
>> 
>> Perhaps, coming to the state:Qt::ApplicationActive from
>> somewhere else and reloading fonts, etc could be a work-around?
>> 
>> Kind regards,
>> Robert