Keep the map design across configuration changes

src/androidTest/java/com/mapconductor/mapbox/MapboxMapViewSaverTest.kt

@@ -0,0 +1,113 @@
+package com.mapconductor.mapbox
+
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.SaverScope
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.mapconductor.core.features.GeoPoint
+import com.mapconductor.core.map.AttributionRule
+import com.mapconductor.core.map.MapCameraPosition
+import com.mapconductor.core.map.MapDesignTypeInterface
+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 [MapboxMapViewSaver] 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 MapboxMapViewSaverTest {
+    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 = MapboxMapDesign.Custom("my-account/my-style", rules)
+        val state = MapboxViewState(mapDesignType = design, id = "mapbox-1", cameraPosition = camera)
+        state.uiSettings = MapUISettings(rotateGesture = false, tiltGesture = false)
+
+        val restored = roundTrip(MapboxMapViewSaver().createSaver(), state)
+
+        val actual = restored.mapDesignType
+        assertTrue(actual is MapboxMapDesign.Custom)
+        assertEquals("my-account/my-style", actual.id)
+        assertEquals(rules, actual.attributionRules)
+        assertCommon(restored, "mapbox-1")
+    }
+
+    @Test
+    fun keepsStyleUriAsStyleUri() {
+        // 以前は id だけを保存して create(id) で戻しており、URI が mapbox://styles/mapbox/<URI> の
+        // Custom になっていた。
+        val design = MapboxMapDesign.StyleUri("https://example.com/style.json", rules)
+        val restored = roundTrip(MapboxMapViewSaver().createSaver(), MapboxViewState(design, "mapbox-2"))
+
+        val actual = restored.mapDesignType
+        assertTrue(actual is MapboxMapDesign.StyleUri)
+        assertEquals("https://example.com/style.json", actual.getValue())
+        assertEquals(rules, actual.attributionRules)
+    }
+
+    @Test
+    fun keepsPresetDesignAsTheSameObject() {
+        val restored = roundTrip(MapboxMapViewSaver().createSaver(), MapboxViewState(MapboxMapDesign.Dark, "mapbox-3"))
+        assertSame(MapboxMapDesign.Dark, restored.mapDesignType)
+    }
+
+    @Test
+    fun appImplementationComesBackWithItsStyle() {
+        val design =
+            object : MapDesignTypeInterface<String> {
+                override val id: String = "app-design"
+                override val attributionRules: List<AttributionRule> = rules
+
+                override fun getValue(): String = "${MapboxMapDesign.MAPBOX_URL}/streets-v12"
+            }
+        val restored = roundTrip(MapboxMapViewSaver().createSaver(), MapboxViewState(design, "mapbox-4"))
+
+        assertEquals(design.getValue(), restored.mapDesignType.getValue())
+        assertEquals(rules, restored.mapDesignType.attributionRules)
+    }
+
+    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/mapbox/MapboxViewStateImpl.kt

@@ -9,6 +9,7 @@ import com.mapconductor.compose.map.BaseMapViewSaver
 import com.mapconductor.core.map.MapCameraPosition
 import com.mapconductor.core.map.MapCameraPositionInterface
 import com.mapconductor.core.map.MapViewState
+import com.mapconductor.core.map.MapViewStateBundle
 import com.mapconductor.core.map.MapViewStateInterface
 import com.mapconductor.mapbox.MapboxMapDesign.Standard
 import java.util.UUID
@@ -39,6 +40,9 @@ class MapboxViewState(
     }
 
     internal fun onMapDesignTypeChange(value: MapboxDesignType) {
+        // 地図から読み戻した値はスタイル URI から作ったデザインで、attributionRules を持たない。
+        // 同じスタイルなら、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
     }
 
@@ -55,7 +59,20 @@ class MapboxMapViewSaver : BaseMapViewSaver<MapboxViewState>() {
         state: MapboxViewState,
         bundle: Bundle,
     ) {
-        bundle.putString("id", state.mapDesignType.id)
+        val design = state.mapDesignType
+        bundle.putString("id", design.id)
+        // id だけでは Custom / StyleUri / 定義済みの区別がつかず、StyleUri（URI そのもの）が
+        // mapbox://styles/mapbox/<uri> の Custom として戻ってしまう。
+        val kind =
+            when (design) {
+                is MapboxMapDesign.StyleUri -> KIND_STYLE_URI
+                is MapboxMapDesign.Custom -> KIND_CUSTOM
+                is MapboxMapDesign -> if (design === MapboxMapDesign.create(design.id)) KIND_PRESET else KIND_VALUE
+                else -> KIND_VALUE
+            }
+        bundle.putString(KEY_KIND, kind)
+        bundle.putString(KEY_VALUE, design.getValue())
+        MapViewStateBundle.putAttributionRules(bundle, design.attributionRules)
     }
 
     override fun createState(
@@ -65,16 +82,42 @@ class MapboxMapViewSaver : BaseMapViewSaver<MapboxViewState>() {
     ): MapboxViewState =
         MapboxViewState(
             id = stateId,
-            mapDesignType =
-                MapboxMapDesign.create(
-                    layerId = mapDesignBundle?.getString("id") ?: Standard.id,
-                ),
+            mapDesignType = restoreDesign(mapDesignBundle),
             cameraPosition = cameraPosition,
         )
 
+    private fun restoreDesign(bundle: Bundle?): MapboxMapDesign {
+        val id = bundle?.getString("id") ?: return Standard
+        val rules = MapViewStateBundle.getAttributionRules(bundle)
+        return when (bundle.getString(KEY_KIND)) {
+            KIND_STYLE_URI -> MapboxMapDesign.StyleUri(uri = id, attributionRules = rules)
+            KIND_CUSTOM -> MapboxMapDesign.Custom(layerId = id, attributionRules = rules)
+            KIND_VALUE -> {
+                // アプリ独自の実装。地図に渡していた値（スタイル URI）から作り直す。
+                val value = bundle.getString(KEY_VALUE) ?: id
+                val prefix = "${MapboxMapDesign.MAPBOX_URL}/"
+                if (value.startsWith(prefix)) {
+                    MapboxMapDesign.Custom(layerId = value.removePrefix(prefix), attributionRules = rules)
+                } else {
+                    MapboxMapDesign.StyleUri(uri = value, attributionRules = rules)
+                }
+            }
+            // KIND_PRESET と、kind を持たない以前の形式
+            else -> MapboxMapDesign.create(layerId = id)
+        }
+    }
+
     override fun getStateId(state: MapboxViewState): 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_KIND = "kind"
+private const val KEY_VALUE = "value"
+private const val KIND_PRESET = "preset"
+private const val KIND_CUSTOM = "custom"
+private const val KIND_STYLE_URI = "styleUri"
+private const val KIND_VALUE = "value"
+
 @Composable
 fun rememberMapboxMapViewState(
     mapDesign: MapboxDesignType = Standard,