Qt4 dialog style set to default after UWP conversion

Stak1945

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.
https://social.msdn.microsoft.com/Forums/windowsapps/en-US/02937f15-83bf-4362-b20e-a9b8ae91fcb3/uwpdesktop-bridgewrong-qt-dialog-style?forum=wpdevelop

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):

After Convertion (UWP):

I wrote a very simple demo application and after conversion the same problem recurred.
Win32:

UWP:

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)));
	spinBox->setValue(20);

	QHBoxLayout* layout = new QHBoxLayout;
	layout->addWidget(spinBox);
	layout->addWidget(slider);
	window->setLayout(layout);

	window->show();
	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.

mrjj

Hi

Seems all styles is stripped/not loading/failed.

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

Also I would try with
http://doc.qt.io/qt-5/qtwidgets-painting-affine-example.html

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.

Stak1945

Hi mrjj,
Thanks for your reply.

I tried the qDebug() and here is the result:
Win32:
Win32
UWP:
UWP
Does it mean Win10 UWP Environment is a specialized unsupported version?

The custom style works fine in our application in UWP environment, like this:

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.

mrjj

@Stak1945
HI
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.

Stak1945

Hi mrjj,

Here are the pictures.
Win32 Debug:
Win32Debug
UWP Debug:

Custom Style of Our Application in UWP Environment:

Thank you:)

mrjj

@Stak1945
Thank you.
Are they ment to be so small? ( even when clicked)

mrjj

Hi
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
http://doc.qt.io/qt-4.8/qstyle.html
and see if it changes anything.

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

Stak1945

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.

mrjj

@Stak1945
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.
QApplication::setStyle();

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. :(

Stak1945

@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:)

mrjj

@Stak1945
Super.
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 ? :)

Stak1945

@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

mrjj

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/