Use BCP-47 LanguageTag in IME/Spell-Checker.
The primary goal of this CL is to make it clear that BCP-47 is the
expected format to annotate locale information for each
{InputMethod, SpellCkecker}Subtype. In order to avoid possible
compatibility issues, this CL introduce a new "languageTag" attribute
instead of reusing existing "imeSubtypeMode" and "subtypeLocale"
attributes.
For IME developers, this CL changes nothing unless "languageTag"
attribute is specified. To summarize:
A: If only legacy locale-string is specified
(existing IMEs/Spell-Checkers fall into this category):
-> The system uses locale-string.
B: If only LanguageTag is specified:
-> The system uses LanguageTag.
C: If both locale-string and languageTag are specified:
-> The system uses LanguageTag. Legacy locale-string is ignored.
For application developers, there should be some follow-ups CLs because
even with this CL most likely they would still have to take care of
previous versions of Android where:
- Locale#forLanguageTag() (N/A in API Level 20 and prior)
- Locale#toLanguageTag() (N/A in API Level 20 and prior)
- InputMethodSubtype#getLocale() (Deprecated in N)
- SpellCheckerSubtype#getLocale() (Deprecated in N)
- InputMethodSubtype#getLanguageTag() (N/A in M and prior)
- SpellCheckerSubtype#getLanguageTag() (N/A in M and prior)
One idea would be is in the official support library to provide a utility
method that takes care of above tasks and just returns a Locale object.
If we had a utility method in the support library, probably not
returning a Locale object from #getLanguageTag() would make sense.
From performance point of view both existing legacy locale-string
attribute and new LanguageTag attribute are just String objects that
travel from XML manifest to system services to applications via IPCs.
Hence there are no performance implications except for having one more
String objects.
Bug: 22858221
Change-Id: I6db107ad2afc7709167f7c4e5d24bd589ac8bd70
10 files changed