fix(android): hide nav & title bars when fullscreen is enabled

[distinctdan]

Platforms affected

Android

Motivation and Context

This is a fix for #180
The issue is that when the app is supposed to be in fullscreen mode, the nav and title bars still display while the splashscreen is visible.

Description

Cordova's main activity currently doesn't set the fullscreen flag until it gets focus, so when we check it on plugin init, it's always false. I've added a fallback to read the Fullscreen preference if cordova hasn't set flags yet. Long term, I'm planning on doing a separate PR to the cordova-android repo to fix it so that it sets it in onCreate instead.

Note: The issue is 90% fixed, but the nav and title bars still flash in briefly when the splashscreen hides. This is because cordova's activity hasn't set its view flags yet and hasn't gotten focus yet. The separate PR to cordova-android will fix this.

Testing

Ran npm test, manually tested the 3 cases of not fullscreen, Fullscreen, and FullscreenNotImmersive.

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

---

closes #180

[peitschie]

Hi!

Just noting, I've tested this on Android 10, and it definitely improves the situation immensely for me.

Is this still being blocked by something? The code presented here makes good sense to me.

[breautek]

lgtm

I haven't ran the code myself but I see other forks applying this change and others who have stated that this change is a major improvement. Additionally the code is well documented.

[NiklasMerz]

I did a quick test and it looks OK. As @breautek said the code is quite clear and well documented.