[Interest] Dynamic translations for mobile apps at runtime?
Jason H
jhihn at gmx.com
Wed Mar 9 15:38:22 CET 2016
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.
> >>>>
> >>
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