⚠️ Forum Maintenance: Feb 6th, 8am - 14pm (UTC+2)

Qt4 dialog style set to default after UWP conversion

  • I asked the same question at Windows Dev Center as well but no answer yet. Hope the Qt side can give some insight into this.

    We have an application built by Qt4. After converting from original Win32 applicatioin to UWP, all the dialogs handled by Qt itself are reset to the default style.
    Before Convertion (Win32):
    Before Convert
    After Convertion (UWP):
    After Convert (UWP)

    I wrote a very simple demo application and after conversion the same problem recurred.

    The demo code:

    #include <qapplication.h>
    #include <QPushButton>
    #include <QHBoxLayout>
    #include <QSlider>
    #include <QSpinBox>
    int main(int argc, char**argv)
    	QApplication app(argc, argv);
    	QWidget* window = new QWidget;
    	window->setWindowTitle("Enter Your Age");
    	QSpinBox* spinBox = new QSpinBox;
    	QSlider* slider = new QSlider(Qt::Horizontal);
    	spinBox->setRange(0, 130);
    	slider->setRange(0, 130);
    	QObject::connect(spinBox, SIGNAL(valueChanged(int)), slider, SLOT(setValue(int)));
    	QObject::connect(slider, SIGNAL(valueChanged(int)), spinBox, SLOT(setValue(int)));
    	QHBoxLayout* layout = new QHBoxLayout;
    	return app.exec();

    The demo package: http://u.163.com/vgTo1qYY Code: 3WCeCoYf

    Anyone has any idea what the problem might be?
    Thanks a lot.

  • Lifetime Qt Champion


    Seems all styles is stripped/not loading/failed.

    Try to print out
    qDebug() << QStyleFactory::keys().join(" ");

    Also I would try with

    it uses a custom Style and if it also go missing
    it must mean/indicate that the Qt style fail in some regards
    when converted to Metro App.

  • Hi mrjj,
    Thanks for your reply.

    I tried the qDebug() and here is the result:
    Does it mean Win10 UWP Environment is a specialized unsupported version?

    The custom style works fine in our application in UWP environment, like this:
    Custom Style
    I didn't try the "qtwidgets-painting-affine-example" cause we are using Qt4 and don't have a Qt5 environment at hand. Thought the application screen short might be suffice to clear the point. So the Qt style is still working.

    What can I infer from the debug message? What further investigation can I take?
    Thank you.

  • Lifetime Qt Champion

    Sadly the forum eats the pictures so i cannot see them. ( you can )
    Could you please upload to say postimage.org and post the links here.

  • Hi mrjj,

    Here are the pictures.
    Win32 Debug:
    UWP Debug:
    UWP Debug
    Custom Style of Our Application in UWP Environment:
    Custom Style of Our Application in UWP Environment

    Thank you:)

  • Lifetime Qt Champion

    Thank you.
    Are they ment to be so small? ( even when clicked)

  • Lifetime Qt Champion

    I don't know enough about modern apps and UWP to guess at this
    but it seems to me that Qt4 seems to think its run in good old win32 and as far as
    I understand what the converter does
    then its running inside a legacy "wrapper"
    So I would go and play with QStyle
    and see if it changes anything.

    Did you try a normal application ? does it also change look when converted ?

  • Strange. Didn't mean to be small. Sorry for that.
    The debug message in Win32 is

    "Windows WindowsXP WindowsVista Motif CDE Plastique Cleanlooks".

    The debug message in UWP is

    Qt: Untested Windows version 10.0 detected!
    "Windows Motif CDE Plastique Cleanlooks"

    What do you mean by normal application?
    Our application is kind of big with probably hundred of dialogs in it, it there a way to fix them all in one place?

    Thank you.

  • Lifetime Qt Champion

    Hi, np.

    Ok so it seems related to Qt4 not knowing win 8+ and never seen the UWP
    runtime environment.

    • What do you mean by normal application?
      As far as I understand, you can convert a desktop app to run in the modern runtime.
      So I was wondering if you took a non Qt app and converted it and ran it , if it
      would change the look too.

    • Our application is kind of big with probably hundred of dialogs in it, it there a way to fix them all in one place?

    if you set the QStyle then it will apply to all.

    Also, you can do
    ./myapplication -style motif
    but not sure its possible in UWP

    So it seems that Qt4 is too old for the "modern" runtime and only style available
    is "Windows" which might look like what u see.

    I dont know what the fix is. :(

  • @mrjj
    Hi mrjj,

    My colleague has figured out how to fix this:D
    As it concerns with not recognizing Windows Version, adding corresponding windows version number to corelib/global/qglobal.h and .cpp fixed this issue.

    Add Win10 support in enum WinVersion, enum MacVersion of qglobal.h and QSysInfo::windowsVersion() of qglobal.cpp.

    Thanks for your help:)

  • Lifetime Qt Champion

    So app was confused what windows a modern universal app wrapper was actually running in :)
    Thank you for reporting back. It will come up again :)

    Oh, can I ask why Q4.8 ?
    You already tons of code and porting it to Qt5.X is simply not
    an option ? :)

  • @mrjj
    Why Qt4? :)
    It's because our application is 28 years old and during the latest refactoring about 5 or 4 years ago we introduced Qt4, really tons of code intertwined with customized Qt4 library. Porting to Qt5 may concern so much code to change and features to test so the plan has been postponed.
    Guess a change to Qt5 will have to wait for another refactoring :D

  • Lifetime Qt Champion

    Ah, yes. in 28 years, one can get quite the amount of code. :)
    Well Qt4.8 should be good for years and besides you just ran it
    in something really new and it worked. \o/

Log in to reply