Gui: fix possibly garbled toolbars and menus

[wwmayer]

See also Debian bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=986821 For now enable this line only for Windows builds

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[freecadci]

for feature branch PR_8783. Pipeline 800050980 was triggered at d32bc0d. All CI branches and pipelines.

[xtemp09]

Can I ask here a question closely related to this kind of style?

Would it be better to define global constants to simplify the code?

Like this:

#ifdef Q_OS_WIN
    bool isOSWindows = true;
    bool isOSLinux = false;
    bool isOSAndroid = false;
#endif

//<some code>
namespace Base::Qt {
    int major = 5;
    int minor = 15;
    int patch = 7;
}

The code you've just sent becomes:

if constexpr ( isOSWindows && (Base::Qt::major == 5) && (Base::Qt::minor > 14) )
        QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);

Therefore, this fragment in /src/Mod/Fem/Gui/DlgSettingsFemElmerImp.cpp

fragment

#if defined(FC_OS_WIN32)
    // name ends with "_mpi.exe"
    if (!FileName.endsWith(QLatin1String("_mpi.exe"))) {
        QMessageBox::warning(this, tr("FEM Elmer: Not suitable for multithreading"),
            tr("Wrong Elmer setting: You use more than one CPU core.\n"
                "Therefore an executable with the suffix '_mpi.exe' is required."));
        ui->sb_elmer_num_cores->setValue(1);
        ui->sb_elmer_num_cores->setMaximum(1);
        return;
    }
#elif defined(FC_OS_LINUX) || defined(FC_OS_CYGWIN) || defined(FC_OS_MACOSX) || defined(FC_OS_BSD)
    // name ends with "_mpi"
    if (!FileName.endsWith(QLatin1String("_mpi"))) {
        QMessageBox::warning(this, tr("FEM Elmer: Not suitable for multithreading"),
            tr("Wrong Elmer setting: You use more than one CPU core.\n"
                "Therefore an executable with the suffix '_mpi' is required."));
        ui->sb_elmer_num_cores->setValue(1);
        ui->sb_elmer_num_cores->setMaximum(1);
        return;
    }
#endif

becomes:

const QString ending = [] (bool os) {
	if (os) return QLatin1String("_mpi.exe");
	else    return QLatin1String("_mpi"); } (isOSWindows);

if ( !FileName.endsWith(ending) ) {
	QMessageBox::warning( this, tr("FEM Elmer: Not suitable for multithreading"),
	tr("Wrong Elmer setting: You use more than one CPU core.\n"
	"Therefore an executable with the suffix '%1' is required.").arg( ending ) );
	ui->sb_elmer_num_cores->setValue(1);
	ui->sb_elmer_num_cores->setMaximum(1);
    }

Usage of constexpr also would be good.

[xtemp09]

I wrote the previous post in the comment field out of frustration, so it should be viewed as an idea. By no means I'm trying to reprimand, I'm just thinking to ease understanding of the code. The code of FreeCAD is complex. Usage of constexpr and if constexpr keywords will simplify it. I'm thinking of the following:

if constexpr ( Base::sysInfo::isOSWindows() ){
	SetProcessDPIAware();
}

if constexpr ( isOSWindows ){
	if constexpr ( Base::QInfo::Version.major < 6){
            QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
	    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
	}
	
	if constexpr (  Base::QInfo::Version.major == 5 &&
			Base::QInfo::Version.minor > 14 ){
        QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::PassThrough);
        }

	if constexpr (  Base::QInfo::Version.major == 5 &&
			Base::QInfo::Version.minor == 10 ){
        QCoreApplication::setAttribute(Qt::AA_CompressTabletEvents);
        }
}

[wwmayer]

Will such code still compile with Qt6 then? Some of the Qt::AA attributes are not available in Qt6 any more and thus I don't think that if constexpr ( Base::QInfo::Version.major < 6){ will work because constexpr does not guarantee that the code will be evaluated at compile time. It can but doesn't have to.

[xtemp09]

Well, it requires some digging. If FreeCAD is being ported to Qt 6, might I ask how QWinTaskbarButton is going to be replaced? It was removed in Qt 6.

I can speak for all Windows users that observing progress of heavy tasks in task bar is incredibly good feature.

[wwmayer]

Apparently there are plans to provide this feature for all platforms. So, it will be part of the official Qt API. But I don't know when this will happen.