Font scale display problem under windows 8.1 /10, Qt5.3.2

  • Hi,
    I have made a software with Qt5.3.2 under Windows 7. the software runs under windows 8.1 and windows 10 too.But on two laptops with windows 8.1 and windows 10 we had a problem with the font scale display of this software because the font scale display was at 125% on these laptops.We set the display at 100 % and the problem was solved.On my developpement pc (windows 7) the display is at 100%.
    can I solve this problem by using Qt5.6 instead of Qt5.3.2 and/or using a Qt or win32 function ? or is there any solution and the user must put the font scale display at 100% on each pc ?

  • Qt Champions 2017

    Qt 5.6 has better support for high DPI

    You can maybe use QT_AUTO_SCREEN_SCALE_FACTOR
    or other features to tweak your app.

    Since its due to the font scale and not so much DPI, its not
    just upgrade and it cures all -- .. but you get better toolbox. :)

  • Ok,
    thank you mrjj.
    I will try it with Qt5.6 and with this funtionality.
    But I have another question: I have looked at the documentation and should I use a class that derivate from QGuiApplication or can I use a class that derivates from QApplication to use this environnement variable ?
    best regards

  • OK QApplication derivates from QGuiApplication so there is no problem.
    I will try it with Qt 5.6 and come back if it solves my problem partially or totally..

  • Qt Champions 2017

    oh, can i see what you have found?
    I was/am not aware any requirements using QGuiApplication/QApplication
    Update: oK :)

  • Yes I have seen that with Qt5.6 and the environment variable QT_AUTO_SCREEN_SCALE_FACTOR or by using QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling); it can perhaps solve my problem.
    So I will try this....

  • Qt Champions 2017

    well it will at least do something to your fonts :)

  • No,
    I have just tested with Qt5.6 and QGuiApplication::setAttribute(Qt::AA_EnableHighDpiScaling); and it doesn't solve the problem of the font...

  • Qt Champions 2017

    but does it react to QT_AUTO_SCREEN_SCALE_FACTOR ?
    did anything happen?

  • No It doesn't react, if I do set QT_AUTO_SCREEN_SCALE_FACTOR=1 and I run the program, the font is too big with font scale display =125%

  • I think we must tell the user to put 100% as font scale display....

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