WPF beta142: stale SingleTile callbacks replay old map positions

[Julian_Thoms]

With a LayerOverlay using TileType.SingleTile, highlighting ~50 features and repeatedly panning causes highlights to replay previous positions after navigation stops. This also occurs with GPU rendering disabled.

Inspection suggests that tile display callbacks queued at DispatcherPriority.ContextIdle survive draw cancellation and can replace newer visible tiles.

Our workaround rejects callbacks from older tile generations and transforms the accepted tile against the current viewport. This resolves the replay.

Could you confirm whether the SDK should suppress these stale callbacks and ensure delayed tiles use the current viewport?

[Ben]

Hi Julian,

It’s recreated and fixed in 15.0.0-beta147.

We chose ContextIdle to make sure the events are raised only after the tile is actually displayed on the map. And yes, there is a bug updating the tiles in that event.

ContextIdle sits below Input, so while you keep dragging none of those callbacks run — they pile up and drain all at once when you stop. Each one then swapped in its own tile without checking whether it was still the one the map wanted, and placed it at the position that was right when its own drawing started. That’s the replay you saw. And you will not see it with beta147 anymore.

Thanks,
Ben