Keep the map design across configuration changes

src/androidTest/java/com/mapconductor/googlemaps/GoogleMapViewSaverTest.kt

@@ -0,0 +1,86 @@
+package com.mapconductor.googlemaps
+
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.SaverScope
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.google.android.gms.maps.GoogleMap
+import com.mapconductor.core.features.GeoPoint
+import com.mapconductor.core.map.AttributionRule
+import com.mapconductor.core.map.MapCameraPosition
+import com.mapconductor.core.map.MapUISettings
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertSame
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import android.os.Bundle
+import android.os.Parcel
+
+/**
+ * 回転などの構成変更で state が [GoogleMapViewSaver] を通って作り直されても、デザイン（id・
+ * attributionRules ほか）と uiSettings・カメラが落ちないこと。Bundle は実機の Parcel を一度通す。
+ */
+@RunWith(AndroidJUnit4::class)
+class GoogleMapViewSaverTest {
+    private val rules =
+        listOf(AttributionRule("© test"), AttributionRule("© ranged", minZoom = 3, maxZoom = 15))
+
+    private val camera =
+        MapCameraPosition(
+            position = GeoPoint(21.38, -157.93),
+            zoom = 12.0,
+            bearing = 20.0,
+            tilt = 10.0,
+        )
+
+    @Test
+    fun keepsCustomDesignWithAttributionRules() {
+        val design = GoogleMapDesign.Custom(GoogleMap.MAP_TYPE_SATELLITE, rules)
+        val state = GoogleMapViewState(id = "google-1", mapDesignType = design, cameraPosition = camera)
+        state.uiSettings = MapUISettings(rotateGesture = false, tiltGesture = false)
+
+        val restored = roundTrip(GoogleMapViewSaver().createSaver(), state)
+
+        // 以前は id だけを保存して Create(id) で戻しており、Satellite（規則なし）になっていた。
+        val actual = restored.mapDesignType
+        assertTrue(actual is GoogleMapDesign.Custom)
+        assertEquals(GoogleMap.MAP_TYPE_SATELLITE, actual.id)
+        assertEquals(rules, actual.attributionRules)
+        assertCommon(restored, "google-1")
+    }
+
+    @Test
+    fun keepsPresetDesignAsTheSameObject() {
+        val state = GoogleMapViewState(id = "google-2", mapDesignType = GoogleMapDesign.Hybrid)
+        assertSame(GoogleMapDesign.Hybrid, roundTrip(GoogleMapViewSaver().createSaver(), state).mapDesignType)
+    }
+
+    private fun assertCommon(
+        restored: com.mapconductor.core.map.MapViewStateInterface<*>,
+        id: String,
+    ) {
+        assertEquals(id, restored.id)
+        assertEquals(false, restored.uiSettings.rotateGesture)
+        assertEquals(false, restored.uiSettings.tiltGesture)
+        assertEquals(true, restored.uiSettings.scrollGesture)
+        assertEquals(12.0, restored.cameraPosition.zoom, 1e-9)
+        assertEquals(20.0, restored.cameraPosition.bearing, 1e-9)
+        assertEquals(21.38, restored.cameraPosition.position.latitude, 1e-9)
+    }
+
+    private fun <T : Any> roundTrip(
+        saver: Saver<T, Bundle>,
+        value: T,
+    ): T {
+        val saved = with(saver) { SaverScope { true }.save(value) }!!
+        // 一度 Parcel に書いて読み戻す（プロセスが落ちたあとの復元と同じ経路）。
+        val parcel = Parcel.obtain()
+        try {
+            parcel.writeBundle(saved)
+            parcel.setDataPosition(0)
+            return saver.restore(parcel.readBundle(javaClass.classLoader)!!)!!
+        } finally {
+            parcel.recycle()
+        }
+    }
+}

src/main/java/com/mapconductor/googlemaps/GoogleMapViewStateImpl.kt

@@ -9,6 +9,7 @@ import com.mapconductor.core.map.MapCameraPosition
 import com.mapconductor.core.map.MapCameraPositionInterface
 import com.mapconductor.core.map.MapPaddings
 import com.mapconductor.core.map.MapViewState
+import com.mapconductor.core.map.MapViewStateBundle
 import com.mapconductor.core.map.MapViewStateInterface
 import java.util.UUID
 import android.os.Bundle
@@ -40,13 +41,17 @@ class GoogleMapViewState(
 
     internal fun setController(controller: GoogleMapViewControllerInterface) {
         this.controller = controller
-//        _mapDesignType.let {
-//            controller.setMapDesignType(it)
-//        }
+        // コントローラが覚えているデザインを state のものにしておく。既定の None のままだと、
+        // 変更リスナーを繋いだ時点で None が state へ返ってきて、復元したデザインを潰す。
+        // 地図は state の mapType で作られているので、地図の見た目は変わらない。
+        controller.setMapDesignType(_mapDesignType)
         attachController(controller)
     }
 
     internal fun onMapDesignTypeChange(value: GoogleMapDesignType) {
+        // 地図から読み戻した値は mapType（Int）から作った定義済みデザインで、attributionRules を
+        // 持たない。同じ mapType なら、アプリが渡した（あるいは復元した）デザインを残す。
+        if (value.getValue() == _mapDesignType.getValue()) return
         _mapDesignType = value
     }
 
@@ -64,26 +69,42 @@ class GoogleMapViewSaver : BaseMapViewSaver<GoogleMapViewState>() {
         state: GoogleMapViewState,
         bundle: Bundle,
     ) {
-        bundle.putInt("id", state.mapDesignType.id)
+        val design = state.mapDesignType
+        bundle.putInt("id", design.id)
+        // 定義済み（Normal など）以外は Custom として戻す。id だけだと Custom の
+        // attributionRules が落ち、定義に無い id は None になってしまう。
+        bundle.putBoolean(KEY_CUSTOM, design !== GoogleMapDesign.toMapDesignType(design.id))
+        MapViewStateBundle.putAttributionRules(bundle, design.attributionRules)
     }
 
     override fun createState(
         stateId: String,
         mapDesignBundle: Bundle?,
         cameraPosition: MapCameraPosition,
-    ): GoogleMapViewState =
-        GoogleMapViewState(
+    ): GoogleMapViewState {
+        val id = mapDesignBundle?.getInt("id", GoogleMapDesign.Normal.id) ?: GoogleMapDesign.Normal.id
+        val design =
+            if (mapDesignBundle?.getBoolean(KEY_CUSTOM) == true) {
+                GoogleMapDesign.Custom(
+                    id = id,
+                    attributionRules = MapViewStateBundle.getAttributionRules(mapDesignBundle),
+                )
+            } else {
+                GoogleMapDesign.Create(id)
+            }
+        return GoogleMapViewState(
             id = stateId,
-            mapDesignType =
-                GoogleMapDesign.Create(
-                    id = mapDesignBundle?.getInt("id") ?: GoogleMapDesign.Normal.id,
-                ),
+            mapDesignType = design,
             cameraPosition = cameraPosition,
         )
+    }
 
     override fun getStateId(state: GoogleMapViewState): String = state.id
 }
 
+// 公開 API の門番（javap）にコンパニオンの定数が載らないよう、ファイル private にする。
+private const val KEY_CUSTOM = "custom"
+
 @Composable
 fun rememberGoogleMapViewState(
     mapDesign: GoogleMapDesign = GoogleMapDesign.Normal,