Widget layer lagging

[Robbendebiene]

Hi, thanks for the awesome work!
For me the main reason not using maplibre with Flutter so far always has been that the widget layer lags behind one or more frames behind the native map layer, caused by flutters architecture which splits the code into a UI and a platform thread. As of today that specific technical limitation seems to be resolved with the thread merge and ffigen packages, however the widget markers in your example app still seem to lag behind. Can you please explain why? If https://flutter-maplibre.pages.dev/docs/architecture is up to date then you still seem to use platform channels through pidgeon for android and iOS. Why is that? And is there a chance the lagging can be resolved? Happy to contribute.

Bildschirmaufzeichnung.vom.2025-10-30.09-58-12.mp4

[josxha]

Yes unfortuately this is a design limitation. All map packages that use platform views like google, mapbox, maplibre_gl and this package have this problem. Similar issue for maplibre_gl is here: maplibre/flutter-maplibre-gl#486

Thanks especially that you consider to look into it, contributions are always welcome.

There are a couple of reasons for this lag:

1. We are indeed using method channels with pigeon for map events like the camera move event. When I implemented it I compared the method channel solution with ffi and method channel was a tiny bit faster at that time. But now that the two used threads have been merged into one things probably have changed and a sync ffi call should be faster. The web implementation does already use interop and has by far less lag.
2. Only after the MapLibre map emits the camera move event, Flutter gets notified and triggers a rebuild of its widgets. That's why the widgets in the WidgetLayer will always lag a bit behind. Question is if its somehow neglectable after changes mentioned in point 1. There is actually one possibliy to get rid of it entirely by using the C++ MapLibre Core SDK and the Flutter Texture Registry. We could then have the rendering of Flutter and MapLibre in sync. There is an open discussion about it and maplibre_gl has currently some movement about it too.

Point 1 is probably manageable. Hopefully it will bring decent improvement.
Point 2 requires knowledge of c/c++ and graphics, so way more advanced. But I'm currently doing some tinkering with it myself. Feel free to try and share any experience with it. 😄

[josxha]

The method channel has now been removed from the android implementation. Will be published in the v0.3.1 release.

[Robbendebiene]

Thanks for the detailed explanation. I completely forgot about the PlatformView.

Only after the MapLibre map emits the camera move event, Flutter gets notified and triggers a rebuild of its widgets. That's why the widgets in the WidgetLayer will always lag a bit behind.

I wonder how they do it on the native MapLibre GL JS SDK for HTML markers. At least it feels kinda similar in the sense that the HTML rendering has to "catch up" with the MapLibre GPU renderer, but I guess since both run in the same world they might be easier to sync.

using the C++ MapLibre Core SDK and the Flutter Texture Registry

Sounds promising but also like a lot of work (also keeping the functionality in sync with the native packages as they progress)

The method channel has now been removed from the android implementation. Will be published in the v0.3.1 release.

Wow, thanks again. Looking forward to it.