Google Play Games Functionality - Achievements

Package-Private Additions via GooglePlayHandler

GooglePlayHandler(Activity activity): as the handler is not an activity, we have to pass in the calling activity (WebPlayerActivity in this case) to be able to later do things such as initiate interactive sign-in and initialize the mxClient helper objects as those either require starting other activites or need an intent to be initialized
startInteractiveSignIn, signInSilently, signOut: Handle signing in and out of Google Play Services. Can also be made into JavascriptInterfaces, if need be (probably should), to facillitate signing in and out in the MV game

Modifications to WebPlayerActivity

onActivityResult(): exists soley to hand off the resulting Intent object to the GooglePlayHandler as the latter is not an activity and is thus unable to make these kinds of calls itself.
initGooglePlayHandler(): initializes mGooglePlayHandler, proceeds to either attempt a silent sign-in or and interactive one depending on the end user (may just leave it at interactive, if desired), and then hooks the Handler up as a JavascriptInterface so the MV game can access achievement-related functions. While I had it implemented in the onCreate method for my testing purposes, I've removed it for this pull request in case it could mess things up for other people.

The Important Additions for the End-User/Game Dev

The following functions are really only to be called via Script/Plugin from the running MV game and, as such, are JavascriptInterfaces

unlockAchievement(...): makes a call to Games Services with the achievement ID (generated via Play Console) as to unlock an achievement.
incrementAchievementByAmount(...): for those achievements similar to "collect X apples" or "kill Y skeletons". Achievement unlock is handled by Games Services once the amount surpasses the threshold input in the game's Play Console
showAchievementWindow(): if the user is connected to Game's Services and things go well, calls up an Activity to show the Achievements UI (provided by Google, so no one needs to touch any layouts or anything). This will pause the game until the window is closed.
ids.xml: end-user will have to provide their own app_id generated by the Play Console for their game for anything to work. Achievement IDs here are optional, since the code deals with those as parameters. I can swap things over to use an enum and a switch-case for unlocking so the user can use, say, ACHIEVEMENT_KILL_SKELETONS as a parameter as opposed to the generated mess that is the actual achievment id, in which case they will need to add their achievment ids to ids.xml and keep track of enum additions themselves.

Possible TODOs

Getting Games Services and achievements working was first and foremost to this pull request, but the framework is kinda there for other things such as

Leaderboards
Events
Using User information (such as username or avatar) for a personalized experience
Achievement 'outbox' in case we lose connectivity with Services and need to store what's been unlocked. However, we have to be able to store that data somewhere in case the user kills the app or the app is otherwise terminated before a connection can be re-established.

Issues

Currently, com.android.support:appcompat-v7:27.0.2 has issues with a support library brought in by the play-services packages due to version mismatch. This does not seem to affect anything from my testing but I believe it's worth noting, just in case.

This is really my first pull request ever, so hopefully I've done things fairly decently. Changes can be made as needed.

I'll do an in-depth review of these changes, but in the meantime there's one thing I'd like to see changed.

This line here: https://github.com/tehguy/mv-android-client/blob/43cb098b34098382b4bc81a5c6465843721fb1bd/app/src/main/java/systems/altimit/rpgmakermv/WebPlayerActivity.java#L134

I don't want end users to have any reason to navigate the Java code - unless they know what they're doing. I think either remove the silent option or make it a def switch in the app build.gradle file as such: https://github.com/tehguy/mv-android-client/blob/43cb098b34098382b4bc81a5c6465843721fb1bd/app/build.gradle#L22

The other thing I want to bring up is; I can't immediately see where initGooglePlayHandler is being used. Was this accidentally removed during a merge?

If this adds dependencies, then this entire feature should probably be toggled by a def switch in gradle. I can imagine that most people won't be using this particular feature, so having the dependencies pulled in for everyone is probably not the kindest thing to do.

This may rain on your parade a bit, but I've been working on the android-api branch for looking into adding Android specific functionality, including a safe (and guaranteed) way to add new Javascript interfaces to the MV Android Client. https://github.com/AltimitSystems/mv-android-client/tree/android-api

I'm thinking that this model may be suitable for adding your feature. We could make it a dedicated google-api feature that is optionally added to projects based on a def switch.

For now, I'll get to fixing the issues with the android-api so I can clean that up and have it committed to master so you can see how I've added this extension feature. I'll be changing how the Javascript interface for that is loaded, too - I'll make it so it's more suitable for your Google Play features.

I'd like to hear your thoughts on all this. I'll make an "API extension" issue dedicated to discussing this.

AltimitSystems / mv-android-client