Keep the map design across configuration changes

build.gradle.kts

@@ -89,6 +89,11 @@ dependencies {
     } else {
         api("com.mapconductor:compose:$libraryVersion")
     }
+
+    testImplementation(libs.junit)
+    // Saver の保存 → 復元を実機の Bundle / Parcel で確かめる（SaverRoundTripTest）。
+    androidTestImplementation(libs.androidx.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
 }
 
 // Set project version for NMCP plugin

src/androidTest/java/com/mapconductor/maptiler/MapTilerMapViewSaverTest.kt

@@ -0,0 +1,102 @@
+package com.mapconductor.maptiler
+
+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.MapUISettings
+import com.maptiler.maptilersdk.map.style.MTMapReferenceStyle
+import com.maptiler.maptilersdk.map.style.MTMapStyleVariant
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.net.URL
+import android.os.Bundle
+import android.os.Parcel
+
+/**
+ * 回転などの構成変更で state が [MapTilerMapViewSaver] 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 MapTilerMapViewSaverTest {
+    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 keepsCustomStyleAndAttributionRules() {
+        // 以前は id だけを保存して fromId で戻しており、定義に無い id は Streets になっていた。
+        val design =
+            MapTilerDesign(
+                id = "my-style",
+                referenceStyle = MTMapReferenceStyle.CUSTOM(URL("https://example.com/style.json")),
+                attributionRules = rules,
+            )
+        val state = MapTilerViewState(mapDesignType = design, id = "maptiler-1", initialCameraPosition = camera)
+        state.uiSettings = MapUISettings(rotateGesture = false, tiltGesture = false)
+
+        val restored = roundTrip(MapTilerMapViewSaver().createSaver(), state)
+
+        val actual = restored.mapDesignType
+        assertEquals("my-style", actual.id)
+        val style = actual.referenceStyle
+        assertTrue(style is MTMapReferenceStyle.CUSTOM)
+        assertEquals("https://example.com/style.json", (style as MTMapReferenceStyle.CUSTOM).url.toString())
+        assertEquals(null, actual.variant)
+        assertEquals(rules, actual.attributionRules)
+        assertCommon(restored, "maptiler-1")
+    }
+
+    @Test
+    fun keepsReferenceStyleAndVariant() {
+        val design = MapTilerDesign("outdoor-dark", MTMapReferenceStyle.OUTDOOR, MTMapStyleVariant.DARK)
+        val restored = roundTrip(MapTilerMapViewSaver().createSaver(), MapTilerViewState(design, "maptiler-2"))
+        assertEquals(design, restored.mapDesignType)
+    }
+
+    @Test
+    fun keepsPresetDesign() {
+        val restored = roundTrip(MapTilerMapViewSaver().createSaver(), MapTilerViewState(MapTilerDesign.StreetsDark, "maptiler-3"))
+        assertEquals(MapTilerDesign.StreetsDark, restored.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/maptiler/MapTilerViewStateImpl.kt

@@ -9,6 +9,10 @@ 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.maptiler.maptilersdk.map.style.MTMapReferenceStyle
+import com.maptiler.maptilersdk.map.style.MTMapStyleVariant
+import java.net.URL
 import android.os.Bundle
 
 /**
@@ -68,20 +72,52 @@ class MapTilerMapViewSaver : BaseMapViewSaver<MapTilerViewState>() {
         state: MapTilerViewState,
         bundle: Bundle,
     ) {
-        bundle.putString(KEY_DESIGN_ID, state.mapDesignType.id)
+        val design = state.mapDesignType
+        bundle.putString(KEY_DESIGN_ID, design.id)
+        when (val style = design.referenceStyle) {
+            is MTMapReferenceStyle.CUSTOM -> bundle.putString(KEY_CUSTOM_STYLE_URL, style.url.toString())
+            else -> bundle.putString(KEY_REFERENCE_STYLE, style.getName())
+        }
+        design.variant?.let { bundle.putString(KEY_VARIANT, it.name) }
+        MapViewStateBundle.putAttributionRules(bundle, design.attributionRules)
     }
 
     override fun createState(
         stateId: String,
         mapDesignBundle: Bundle?,
         cameraPosition: MapCameraPosition,
-    ): MapTilerViewState {
-        val designId = mapDesignBundle?.getString(KEY_DESIGN_ID)
-        return MapTilerViewState(
-            mapDesignType = MapTilerDesign.fromId(designId),
+    ): MapTilerViewState =
+        MapTilerViewState(
+            mapDesignType = restoreDesign(mapDesignBundle),
             id = stateId,
             initialCameraPosition = cameraPosition,
         )
+
+    /**
+     * id だけで [MapTilerDesign.fromId] に頼ると、定義に無いデザイン（独自のスタイル URL や
+     * バリアントの組み合わせ）は Streets に化け、attributionRules も落ちる。
+     * スタイルとバリアントも保存して作り直す。
+     */
+    private fun restoreDesign(bundle: Bundle?): MapTilerDesign {
+        val designId = bundle?.getString(KEY_DESIGN_ID)
+        val referenceStyle =
+            bundle?.getString(KEY_CUSTOM_STYLE_URL)?.let { url ->
+                runCatching { MTMapReferenceStyle.CUSTOM(URL(url)) }.getOrNull()
+            } ?: bundle?.getString(KEY_REFERENCE_STYLE)?.let { name ->
+                MTMapReferenceStyle.all().firstOrNull { it.getName() == name }
+            }
+        // スタイルを持たない以前の形式は id から引く。
+        if (designId == null || referenceStyle == null) return MapTilerDesign.fromId(designId)
+        val variant =
+            bundle.getString(KEY_VARIANT)?.let { name ->
+                MTMapStyleVariant.values().firstOrNull { it.name == name }
+            }
+        return MapTilerDesign(
+            id = designId,
+            referenceStyle = referenceStyle,
+            variant = variant,
+            attributionRules = MapViewStateBundle.getAttributionRules(bundle),
+        )
     }
 
     override fun getStateId(state: MapTilerViewState): String = state.id
@@ -91,6 +127,11 @@ class MapTilerMapViewSaver : BaseMapViewSaver<MapTilerViewState>() {
     }
 }
 
+// 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_REFERENCE_STYLE = "maptiler_reference_style"
+private const val KEY_CUSTOM_STYLE_URL = "maptiler_custom_style_url"
+private const val KEY_VARIANT = "maptiler_variant"
+
 /**
  * [MapTilerViewState] を生成・記憶する Composable ファクトリ。
  *