Remove black surface during map start up

[tobrun]

Closes #10990, this PR exposes a color int configuration on MapboxMapOptions that is used as foreground color during map startup. Only when the style has loaded, we will show the render surface. This results in removing the black flash as shown in #10990.

[tobrun]

Not really satisfied with current exposed naming of loadColor, looking for alternatives

edit: went with foregroundLoadColor instead.

[LukasPaczos]

🚀

[tobrun]

Been trying out a couple of configurations (different map change events) to see if we can remove the black surface as seen on some lower end devices.

Hooking into MapView#DID_FINISH_RENDERING_FRAME_FULLY_RENDERED atm does seem to work reliably to hide the black surface.

[tobrun]

@LukasPaczos would you be able to re-review? I took a different approach in 3dc0365

[LukasPaczos]

I think there is a typo here. As you mentioned, MapView#DID_FINISH_RENDERING_FRAME_FULLY_RENDERED works as expected, but MapView#DID_FINISH_RENDERING_FRAME doesn't resolve the issue.

[tobrun]

forgot to document my follow up findings:
I found that MapView#DID_FINISH_RENDERING_FRAME_FULLY_RENDERED was taking a long time to show the map to the end user. Before core emits that event we receive multiple MapView#DID_FINISH_RENDERING_FRAME with every render invocation we render a bit more content overtime. First time we render the black surface, second time we render the background (this is why there is a counter there). Feel free to play around this yourself but I feel this was providing a better UX.

[LukasPaczos]

Please check out the following setup in the MapboxMap#onStart that imitates bad connection:

void onStart() {
  nativeMapView.update();
  if (TextUtils.isEmpty(nativeMapView.getStyleUrl()) && TextUtils.isEmpty(nativeMapView.getStyleJson())) {
    // if user hasn't loaded a Style yet
    new Handler().postDelayed(() -> nativeMapView.setStyleUrl(Style.MAPBOX_STREETS), 2000L);
  }
}

Waiting for MapView#DID_FINISH_RENDERING_FRAME_FULLY_RENDERED here does the job well, but if you feel like it's too long, maybe you could wait for the style to load and then wait for those 2 frames to be partially rendered?

[tobrun]

Thank you for testing and catching that use-case! I implemented the latter suggestion and I feel it's working great for normal usage as for this specific case. LMK what you think.

[LukasPaczos]

🚀

[sictiru]

Can you do the same thing when the map gets destroyed ? I don't see the black screen on start up anymore but do every time when switching to the next fragments in a view pager.