[Development] Revisiting high-DPI configuration options

Frank Hemer frank at hemer.org
Tue Jul 19 12:07:31 CEST 2016

On Tuesday 19 July 2016 11:57:20 Prav wrote:
> Hello, Everyone!
> > The scope of this is the Qt::AA_EnanbleHighDpiScaling mode. I’d like to
> > 
> > focus on two aspects:
> >     1) Automatic scale factor configuration based on system settings.
> There so many debates about this topic and how to get real DPI for all
> devices correctly. But I personally does get this as SO important thing.
> And this is because people are different and have different preferences
> about reading from screen (because of eyes or just personally). Which
> brings me to understanding that it does not matter what is the DPI of
> screen. It matter only how large PERSON want program font normally be.
> So I would expect that the main intention in developing of apps should be
> moved toward giving the user possibility to scale the app.
> And you are done!
> All this problems in getting correct DPI of screen would NOT be so painfull.
> Your phone or monitor or OS or something resulted in incorrect scale
> factor? ... does not matter! ... increase/decrease scale factor for that
> app as you like ... and here you are ... having this app comfortable for
> eyes and personal preferences (not for DPI of scrrent ... most people even
> do not know what it is and why they should care)! App should remember of
> couse this setting to restore it back at restart
> >     2) Handling fractional scale factors (rounding).
> Previous idea need fractional scale factors to work ... FOR SURE!
> PS I can give many more cases then getting right DPI does not give usability
> to user. 1. Developers or Designers are young, have good eyes are pretty
> conformable with small fonts. They produce app with HighDPI support which
> correctly scales to DPI of HighDPI user device. But ... this does not mean
> that old persons would feel comfortable with the app ... their eyes see not
> as good as when they were young. 2. Could be a reverse case ... like you
> want smaller because devs created app which seems larger to you. 3. Devs
> and Designers usually have good tech. I mean good monitors, modern phones
> with good crisp screen. But user's tablet/phone can be not modern or be
> cheap or with tons of scratches (for example with plastic (not glass
> screens)). Sooo ... visibility is much worse ... but DPI could be same.
> 4. You are OK with design and size of app's fonts at your notebook/tablet
> with like 10'', devs and designer see things the same good as you and your
> screen is modern and good with gorilla glass or something same and DPI
> scale factor was determined exactly as it is. But now you are inside city
> transport ... and guess what ...
>     you are shaken! ... and this mean you see the screen worse ... you need
> to increase the scale! And if you sit/lay still in the bedroom you what
> smaller font to see more info at once.
> I have nothing against getting right DPI at app's startup ...
> I wanted just to say that I see that it is actually NOT THE MAIN PURPOSE!
> ... for usability!
> May be Qt need to move accents from getting right DPI to making it user
> changeable ... FRACTIONALLY (as a good new practice)! Like 10-20 % steps
> ... not just 2,3,4,5.
> I do not see much trend in Qt-discussions/apps-interfaces about user-defined
> scale factor. But only THIS is important to user. And NOT DPI ;)

Precisely my experience


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