When adding new strings to be localized, update intl_en.arb, which is used by this project as the template. When creating new entries, they have to be in the following format:
"dartGetterVariableName": "english translation of the message", "@dartGetterVariableName": { "description": "description that the localizations delegate will use." },
In this example, dartGetterVariableName should be the Dart method/property name that you will be using in your localizations delegate.
After adding the new message in intl_en.arb, it can be used in the app by regenerating the GalleryLocalizations delegate. This allows use of the English message through your localizations delegate in the application code immediately without having to wait for the translations to be completed.
Running the application for the first time should generate a synthetic package containing the app's localizations through importing package:flutter_gen/gen_l10n/. The code is generated will be generated in .dart_tool/flutter_gen/gen_l10n/.
The generated localizations code is updated every time flutter run is called, and during hot reload and restart. This means that updates to existing arb files can be made and seen in real time during app development.
From the root directory, run:
flutter gen-l10n \ --template-arb-file=intl_en.arb \ --output-localization-file=gallery_localizations.dart \ --output-class=GalleryLocalizations
From the root directory, run dart tool/l10n_cli/main.dart, which will generate intl_en_US.xml. This will be used by the internal translation console to generate messages in the different locales.
Note that the filename for intl_en_US.xml is used by the internal translation console and changing the filename may require manually updating already translated messages to point to the new file. Therefore, avoid doing so unless necessary.
Once the translations are ready, use the internal tool (push_l10n) to push the updated intl_<locale>.arb files to this repo. For more information, see /third_party/dart/flutter_gallery/README.md.