perf: update overlays in place, coalesce marker refreshes, fix quadratic clustering

package/android/src/main/java/com/margelo/nitro/nitromaps/CircleDescriptor+CircleOptions.kt

@@ -1,5 +1,7 @@
 package com.margelo.nitro.nitromaps
 
+import android.graphics.Color
+import com.google.android.gms.maps.model.Circle
 import com.google.android.gms.maps.model.CircleOptions
 import com.google.android.gms.maps.model.LatLng
 
@@ -15,3 +17,13 @@ fun CircleDescriptor.toCircleOptions(): CircleOptions {
 
   return options
 }
+
+/** Updates an existing circle in place, with the same defaults as [toCircleOptions]. */
+fun CircleDescriptor.applyTo(circle: Circle) {
+  circle.center = LatLng(center.latitude, center.longitude)
+  circle.radius = radius
+  circle.strokeColor = strokeColor?.toColorInt() ?: Color.BLACK
+  circle.fillColor = fillColor?.toColorInt() ?: Color.TRANSPARENT
+  circle.strokeWidth = (strokeWidth ?: 2.0).toFloat()
+  circle.isClickable = tappable != false
+}

package/android/src/main/java/com/margelo/nitro/nitromaps/GoogleMapProviderAdapter.kt

@@ -15,6 +15,7 @@ import com.google.android.gms.maps.CameraUpdateFactory
 import com.google.android.gms.maps.GoogleMap
 import com.google.android.gms.maps.GoogleMapOptions
 import com.google.android.gms.maps.MapView
+import com.google.android.gms.maps.model.CameraPosition
 import com.google.android.gms.maps.model.LatLng
 import com.google.android.gms.maps.model.LatLngBounds
 import com.google.android.gms.maps.model.MapStyleOptions
@@ -39,6 +40,8 @@ class GoogleMapProviderAdapter(
   private var pendingPolygons: Array<PolygonDescriptor>? = null
   private var pendingCircles: Array<CircleDescriptor>? = null
   private val mainHandler = Handler(Looper.getMainLooper())
+  private var lastAppliedRegion: Region? = null
+  private var lastAppliedRegionCamera: CameraPosition? = null
 
   private val googleMapIdAtCreation: String? = normalizeGoogleMapId(initialGoogleMapId)
 
@@ -573,19 +576,36 @@ class GoogleMapProviderAdapter(
 
   private fun applyRegion(region: Region, animated: Boolean = false) {
     val map = googleMap ?: return
-    val bounds = region.toLatLngBounds()
-    val paddingPx = _mapPadding.toPaddingPixels()
+    runWhenMapViewLaidOut { fitCamera(map, region, animated) }
+  }
 
-    val runUpdate = {
-      val update = CameraUpdateFactory.newLatLngBounds(bounds, paddingPx)
-      if (animated) {
-        map.animateCamera(update)
-      } else {
-        map.moveCamera(update)
-      }
+  private fun fitCamera(map: GoogleMap, region: Region, animated: Boolean) {
+    val lastRegion = lastAppliedRegion
+    val lastCamera = lastAppliedRegionCamera
+    if (
+      lastRegion != null &&
+      lastCamera != null &&
+      region.approximatelyEquals(lastRegion) &&
+      map.cameraPosition.approximatelyEquals(lastCamera)
+    ) {
+      // Same region as last time and the camera has not moved since, so the
+      // fit would land on the camera the map already shows.
+      return
     }
 
-    runWhenMapViewLaidOut(runUpdate)
+    val update = CameraUpdateFactory.newLatLngBounds(
+      region.toLatLngBounds(),
+      _mapPadding.toPaddingPixels(),
+    )
+    if (animated) {
+      map.animateCamera(update)
+      // The camera settles later; there is nothing reliable to remember yet.
+      lastAppliedRegionCamera = null
+    } else {
+      map.moveCamera(update)
+      lastAppliedRegionCamera = map.cameraPosition
+    }
+    lastAppliedRegion = region
   }
 
   private fun updateMapCamera(
@@ -749,6 +769,8 @@ class GoogleMapProviderAdapter(
     _mapType = MapType.STANDARD
     _region = null
     _camera = null
+    lastAppliedRegion = null
+    lastAppliedRegionCamera = null
     scrollEnabled = true
     zoomEnabled = true
     rotateEnabled = true

package/android/src/main/java/com/margelo/nitro/nitromaps/MapApproximateEquality.kt

@@ -2,6 +2,7 @@ package com.margelo.nitro.nitromaps
 
 object MapApproximateEquality {
   const val COORDINATE_EPSILON: Double = 1e-6
+  const val SPAN_EPSILON: Double = 1e-6
   const val ZOOM_EPSILON: Float = 1e-4f
   const val ANGLE_EPSILON: Float = 1e-3f
 }