Keep an unset camera property from the current camera, and honour an explicit 0

api/android-sdk-core.api

@@ -852,14 +852,18 @@ public final class com.mapconductor.core.map.LocalMapOverlayRegistryKt {
 }
 public final class com.mapconductor.core.map.MapCameraPosition implements com.mapconductor.core.map.MapCameraPositionInterface {
   public static final com.mapconductor.core.map.MapCameraPosition$Companion Companion;
-  public com.mapconductor.core.map.MapCameraPosition(com.mapconductor.core.features.GeoPointInterface, double, double, double, com.mapconductor.core.map.MapPaddingsInterface, com.mapconductor.core.map.VisibleRegion);
-  public com.mapconductor.core.map.MapCameraPosition(com.mapconductor.core.features.GeoPointInterface, double, double, double, com.mapconductor.core.map.MapPaddingsInterface, com.mapconductor.core.map.VisibleRegion, int, kotlin.jvm.internal.DefaultConstructorMarker);
-  public double getZoom();
-  public double getBearing();
-  public double getTilt();
+  public com.mapconductor.core.map.MapCameraPosition(com.mapconductor.core.features.GeoPointInterface, java.lang.Double, java.lang.Double, java.lang.Double, com.mapconductor.core.map.MapPaddingsInterface, com.mapconductor.core.map.VisibleRegion);
+  public com.mapconductor.core.map.MapCameraPosition(com.mapconductor.core.features.GeoPointInterface, java.lang.Double, java.lang.Double, java.lang.Double, com.mapconductor.core.map.MapPaddingsInterface, com.mapconductor.core.map.VisibleRegion, int, kotlin.jvm.internal.DefaultConstructorMarker);
   public com.mapconductor.core.map.MapPaddingsInterface getPaddings();
   public com.mapconductor.core.map.VisibleRegion getVisibleRegion();
   public com.mapconductor.core.features.GeoPoint getPosition();
+  public double getZoom();
+  public double getBearing();
+  public double getTilt();
+  public final boolean isZoomSpecified();
+  public final boolean isBearingSpecified();
+  public final boolean isTiltSpecified();
+  public final com.mapconductor.core.map.MapCameraPosition resolvedOnto(com.mapconductor.core.map.MapCameraPositionInterface);
   public final boolean equals(com.mapconductor.core.map.MapCameraPositionInterface);
   public final com.mapconductor.core.map.MapCameraPosition copy(com.mapconductor.core.features.GeoPointInterface, java.lang.Double, java.lang.Double, java.lang.Double, com.mapconductor.core.map.MapPaddingsInterface, com.mapconductor.core.map.VisibleRegion);
   public int hashCode();

src/main/java/com/mapconductor/core/map/MapCameraPositionBase.kt

@@ -32,32 +32,75 @@ interface MapCameraPositionInterface {
 
 class MapCameraPosition(
     position: GeoPointInterface,
-    override val zoom: Double = 0.0,
-    override val bearing: Double = 0.0,
-    override val tilt: Double = 0.0,
+    zoom: Double? = null,
+    bearing: Double? = null,
+    tilt: Double? = null,
     override val paddings: MapPaddingsInterface? = MapPaddings.Companion.Zeros,
     override val visibleRegion: VisibleRegion? = null,
 ) : MapCameraPositionInterface {
     override val position: GeoPoint = GeoPoint.from(position)
 
+    // 指定された値。null は未指定。
+    private val givenZoom: Double? = zoom
+    private val givenBearing: Double? = bearing
+    private val givenTilt: Double? = tilt
+
+    /** 指定されなかったときは 0。指定されたかどうかは [isZoomSpecified] で区別する。 */
+    override val zoom: Double = zoom ?: 0.0
+
+    /** 指定されなかったときは 0。指定されたかどうかは [isBearingSpecified] で区別する。 */
+    override val bearing: Double = bearing ?: 0.0
+
+    /** 指定されなかったときは 0。指定されたかどうかは [isTiltSpecified] で区別する。 */
+    override val tilt: Double = tilt ?: 0.0
+
+    /**
+     * `zoom` / `bearing` / `tilt` が明示されたか。
+     *
+     * 明示された 0（zoom 0 = 世界全体、真北、真上から）と未指定を区別するために持つ。
+     * [MapViewState.moveCameraTo] は未指定のプロパティだけを現在のカメラから
+     * 引き継ぐ（[resolvedOnto]）。
+     */
+    val isZoomSpecified: Boolean get() = givenZoom != null
+    val isBearingSpecified: Boolean get() = givenBearing != null
+    val isTiltSpecified: Boolean get() = givenTilt != null
+
+    /**
+     * 未指定の `zoom` / `bearing` / `tilt` を [current] の値で埋めたカメラを返す。
+     *
+     * 明示されたプロパティは、0 であってもそのまま使う。
+     */
+    fun resolvedOnto(current: MapCameraPositionInterface): MapCameraPosition {
+        if (isZoomSpecified && isBearingSpecified && isTiltSpecified) return this
+        return MapCameraPosition(
+            position = position,
+            zoom = givenZoom ?: current.zoom,
+            bearing = givenBearing ?: current.bearing,
+            tilt = givenTilt ?: current.tilt,
+            paddings = paddings,
+            visibleRegion = visibleRegion,
+        )
+    }
+
     fun equals(other: MapCameraPositionInterface): Boolean =
         this.position.equals(other = other.position) &&
             this.zoomEquals(other) &&
             this.bearingEquals(other) &&
             this.tiltEquals(other)
 
+    // 渡されなかったプロパティは、未指定だったならコピー後も未指定のまま。
     fun copy(
         position: GeoPointInterface? = this.position,
-        zoom: Double? = this.zoom,
-        bearing: Double? = this.bearing,
-        tilt: Double? = this.tilt,
+        zoom: Double? = this.givenZoom,
+        bearing: Double? = this.givenBearing,
+        tilt: Double? = this.givenTilt,
         paddings: MapPaddingsInterface? = this.paddings,
         visibleRegion: VisibleRegion? = this.visibleRegion,
     ) = MapCameraPosition(
         position = position ?: this.position,
-        zoom = zoom ?: this.zoom,
-        bearing = bearing ?: this.bearing,
-        tilt = tilt ?: this.tilt,
+        zoom = zoom ?: this.givenZoom,
+        bearing = bearing ?: this.givenBearing,
+        tilt = tilt ?: this.givenTilt,
         paddings = paddings ?: this.paddings,
         visibleRegion = visibleRegion ?: this.visibleRegion,
     )

src/main/java/com/mapconductor/core/map/MapViewState.kt

@@ -169,22 +169,25 @@ abstract class MapViewState<ActualMapDesignType>(
         cameraPosition: MapCameraPosition,
         durationMillis: Long?,
     ) {
+        // 明示されたプロパティは 0 でもそのまま使い、未指定のものだけ現在のカメラから
+        // 引き継ぐ。`MapCameraPosition(position = ...)` なら位置だけが動く。
+        val resolved = cameraPosition.resolvedOnto(_cameraPosition)
         val ctrl = attachedMapController
         if (ctrl == null) {
             // まだ地図が無い。接続時に attachController がこの位置へ移動する。
-            _cameraPosition = cameraPosition
+            _cameraPosition = resolved
             return
         }
         if (optimisticCameraUpdate) {
-            _cameraPosition = cameraPosition
+            _cameraPosition = resolved
         }
         // 引数は既に MapCameraPosition なので、プロバイダごとの
         // `MapCameraPosition.Companion.from` は恒等変換になる（どの実装も
         // `is MapCameraPosition -> position` で素通しする）。ここでは呼ばない。
         if (durationMillis == null || durationMillis == 0L) {
-            ctrl.moveCamera(cameraPosition)
+            ctrl.moveCamera(resolved)
         } else {
-            ctrl.animateCamera(cameraPosition, durationMillis)
+            ctrl.animateCamera(resolved, durationMillis)
         }
     }
 

src/test/java/com/mapconductor/core/map/CameraPositionResolveTest.kt

@@ -0,0 +1,89 @@
+package com.mapconductor.core.map
+
+import com.mapconductor.core.features.GeoPoint
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * 未指定の zoom / bearing / tilt だけが現在のカメラから引き継がれ、
+ * 明示された 0 はそのまま使われることを確認する。
+ *
+ * ios-sdk の `CameraPositionResolveTests`、js-sdk の `CameraPositionResolve.test.mjs` と同じ観点。
+ */
+class CameraPositionResolveTest {
+    private val tokyo = GeoPoint(latitude = 35.6812, longitude = 139.7671)
+    private val osaka = GeoPoint(latitude = 34.7025, longitude = 135.4959)
+    private val current = MapCameraPosition(position = tokyo, zoom = 12.0, bearing = 30.0, tilt = 45.0)
+
+    private fun MapCameraPosition.zbt() = listOf(zoom, bearing, tilt)
+
+    @Test
+    fun positionOnlyKeepsEverythingElse() {
+        val resolved = MapCameraPosition(position = osaka).resolvedOnto(current)
+        assertEquals(osaka.latitude, resolved.position.latitude, 0.0)
+        assertEquals(listOf(12.0, 30.0, 45.0), resolved.zbt())
+    }
+
+    @Test
+    fun explicitZeroIsHonoured() {
+        val resolved =
+            MapCameraPosition(position = osaka, zoom = 0.0, bearing = 0.0, tilt = 0.0)
+                .resolvedOnto(current)
+        assertEquals(listOf(0.0, 0.0, 0.0), resolved.zbt())
+    }
+
+    @Test
+    fun eachPropertyIsInheritedOnItsOwn() {
+        assertEquals(
+            listOf(0.0, 30.0, 45.0),
+            MapCameraPosition(position = osaka, zoom = 0.0).resolvedOnto(current).zbt(),
+        )
+        assertEquals(
+            listOf(12.0, 0.0, 45.0),
+            MapCameraPosition(position = osaka, bearing = 0.0).resolvedOnto(current).zbt(),
+        )
+        assertEquals(
+            listOf(12.0, 30.0, 0.0),
+            MapCameraPosition(position = osaka, tilt = 0.0).resolvedOnto(current).zbt(),
+        )
+    }
+
+    @Test
+    fun unsetReadsAsZeroBeforeResolving() {
+        val camera = MapCameraPosition(position = osaka)
+        assertEquals(0.0, camera.zoom, 0.0)
+        assertFalse(camera.isZoomSpecified)
+        assertFalse(camera.isBearingSpecified)
+        assertFalse(camera.isTiltSpecified)
+        assertTrue(MapCameraPosition.Default.isZoomSpecified)
+    }
+
+    @Test
+    fun copyKeepsUnspecifiedUnlessGiven() {
+        assertFalse(MapCameraPosition(position = osaka).copy(position = tokyo).isZoomSpecified)
+
+        val withZoom = MapCameraPosition(position = osaka).copy(zoom = 0.0)
+        assertTrue(withZoom.isZoomSpecified)
+        assertFalse(withZoom.isBearingSpecified)
+    }
+
+    private class TestState(
+        initial: MapCameraPosition,
+    ) : MapViewState<String>(initial) {
+        override val id: String = "test"
+        override var mapDesignType: String = "design"
+    }
+
+    @Test
+    fun mapViewStateMergesUnsetPropertiesFromCurrentCamera() {
+        val state = TestState(current)
+
+        state.moveCameraTo(MapCameraPosition(position = osaka, bearing = 0.0), null)
+        assertEquals(listOf(12.0, 0.0, 45.0), state.cameraPosition.zbt())
+
+        state.moveCameraTo(MapCameraPosition(position = osaka, zoom = 0.0), null)
+        assertEquals(0.0, state.cameraPosition.zoom, 0.0)
+    }
+}