[Interest] Dynamic translations for mobile apps at runtime?

[Jason H]

Great clarification, thanks Andre!

> Sent: Wednesday, March 09, 2016 at 2:24 AM
> From: "André Somers" <andre at familiesomers.nl>
> To: interest at qt-project.org
> Subject: Re: [Interest] Dynamic translations for mobile apps at runtime?
>
> 
> 
> Op 08/03/2016 om 23:21 schreef Jason H:
> > Sounds like there should be a qApp->translations() that we can use to remove all currently installed translations? Without it, we have to do what you do.
> Just keep the translators you currently have active around, not all of 
> them. It is useless to new a QTranslator for languages you are not 
> actually using. When switching language, you can remove and then delete 
> the already loaded ones after installing the translations for the newly 
> selected language.
> 
> So, something like this (untested code, typed in email editor):
> 
> QString m_currentLanguage;
> QVector<QTranslator*> m_currentTranslations; //note that for any language, you may need multiple translation files!
> 
> void Backend::selectLanguage( QString language ) {
>    if (language == m_currentLanguage)
>      return;
> 
>    QVector oldTranslators = m_currentTranslations;
>    m_currentTranslations.clear();
> 
>    //repeat for every translation file you need to install, ie for your own app, for Qt itself, for libraries...
>    translator = new QTranslator(this);
>    translator->load( language, commonPath()+"/translations" );
>    qApp->installTranslator(translator);
>    m_currentTranslations.append(translator);
> 
>    //now, get rid of the old translators
>    foreach(QTranslator* oldTranslator, oldTranslators) {
>      qApp->removeTranslator(oldTranslator);
>      delete oldTranslator;
>    }
> }
> 
> 
> 
> André
> 
> >
> >
> >> Sent: Tuesday, March 08, 2016 at 3:44 PM
> >> From: Gianluca <gmaxera at gmail.com>
> >> To: "Jason H" <jhihn at gmx.com>
> >> Cc: "interest at qt-project.org" <interest at qt-project.org>
> >> Subject: Re: [Interest] Dynamic translations for mobile apps at runtime?
> >>
> >> qApp->installTranslator add a new translation into the stack. Does not remove the old ones.
> >> So, if the user click 10 times: Italian - English - Italian - English … etc…
> >> you got ten translator into the memory.
> >> That’s because the translation is searched into the order on which the translator are installed into the stack.
> >>
> >> That’s why I remove everything so there is only one translators at time into the memory.
> >>
> >> Il giorno 08/mar/2016, alle ore 18:46, Jason H <jhihn at gmx.com> ha scritto:
> >>
> >>> I'm wondering why you load all those languages and then remove all but one of them? Being a mobile app, I have to be somewhat conscience of memory foot print. Do you see anything wrong with:
> >>>
> >>> void Backend::selectLanguage( QString language ) {
> >>>     translator = new QTranslator(this);
> >>>     translator->load( language, commonPath()+"/translations" );
> >>>     qApp->installTranslator(translator);
> >>> }
> >>>
> >>> ?
> >>>
> >>>
> >>>> Hello Jason,
> >>>> I got the same issue some times ago … and I found that it’s possible to use the translation feature of Qt … that seems static, but it’s not.
> >>>> And localize.biz it’s a wonderful site that allow you to modify Qt translation files directly on web and download the updated one.
> >>>>
> >>>> The trick to achieve (summarized) is the following:
> >>>> Somewhere in your code maintain and update from remote an array of Translators:
> >>>> 	translators["en"] = new QTranslator(this);
> >>>> 	translators["en"]->load( "tr_en", commonPath()+"/translations" );
> >>>> 	translators["de"] = new QTranslator(this);
> >>>> 	translators["de"]->load( "tr_de", commonPath()+"/translations" );
> >>>> 	translators["fr"] = new QTranslator(this);
> >>>> 	translators["fr"]->load( "tr_fr", commonPath()+"/translations" );
> >>>> 	translators["ru"] = new QTranslator(this);
> >>>> 	translators["ru"]->load( "tr_ru", commonPath()+"/translations" );
> >>>> You can change these entry with new files downloaded at runtime.
> >>>>
> >>>> Then you implement a method that you call at runtime for changing the translator, something like that:
> >>>>
> >>>> void Backend::selectLanguage( QString language ) {
> >>>> 	foreach( QString lang, translators.keys() ) {
> >>>> 		if ( lang == language ) {
> >>>> 			qApp->installTranslator( translators[lang] );
> >>>> 		} else {
> >>>> 			qApp->removeTranslator( translators[lang] );
> >>>> 		}
> >>>> 	}
> >>>> 	this->language = language;
> >>>> 	emit languageChanged();
> >>>> }
> >>>> And then there is the final trick:
> >>>> You create a “fake” property that is always an empty string but it’s binded to languageChanged signal:
> >>>>
> >>>> Q_PROPERTY( QString es READ getES NOTIFY languageChanged )
> >>>>
> >>>> And (the most annoying part), append this empty string to all string you want to change at runtime like that:
> >>>>
> >>>> qsTr("NEWS<br/>HUB")+backend.es
> >>>>
> >>>> And close the loop.
> >>>>
> >>>> What will happen is the following: the translator change at runtime and you trigger a languageChanged that trigger an update of all string that got backend.es appended that trigger the call of qsTr that take the new translation from the new translator.
> >>>>
> >>
> > _______________________________________________
> > Interest mailing list
> > Interest at qt-project.org
> > http://lists.qt-project.org/mailman/listinfo/interest
> 
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>