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

Sources/MapConductorCore/map/MapCameraPositionBase.swift

@@ -54,29 +54,61 @@ public protocol MapCameraPositionProtocol {
 
 public final class MapCameraPosition: MapCameraPositionProtocol {
     public var position: GeoPointProtocol { positionValue }
+    /// 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。
     public let zoom: Double
+    /// 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。
     public let bearing: Double
+    /// 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。
     public let tilt: Double
     public let paddings: MapPaddingsProtocol?
     public let visibleRegion: VisibleRegion?
     private let positionValue: GeoPoint
 
+    /// `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(cameraPosition:durationMillis:)`` 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（``resolved(onto:)``）。
+    public let isZoomSpecified: Bool
+    public let isBearingSpecified: Bool
+    public let isTiltSpecified: Bool
+
     public init(
         position: GeoPointProtocol,
-        zoom: Double = 0.0,
-        bearing: Double = 0.0,
-        tilt: Double = 0.0,
+        zoom: Double? = nil,
+        bearing: Double? = nil,
+        tilt: Double? = nil,
         paddings: MapPaddingsProtocol? = MapPaddings.Zeros,
         visibleRegion: VisibleRegion? = nil
     ) {
         self.positionValue = GeoPoint.from(position: position)
-        self.zoom = zoom
-        self.bearing = bearing
-        self.tilt = tilt
+        self.zoom = zoom ?? 0.0
+        self.bearing = bearing ?? 0.0
+        self.tilt = tilt ?? 0.0
+        self.isZoomSpecified = zoom != nil
+        self.isBearingSpecified = bearing != nil
+        self.isTiltSpecified = tilt != nil
         self.paddings = paddings
         self.visibleRegion = visibleRegion
     }
 
+    /// 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。
+    public func resolved(onto current: MapCameraPositionProtocol) -> MapCameraPosition {
+        if isZoomSpecified && isBearingSpecified && isTiltSpecified {
+            return self
+        }
+        return MapCameraPosition(
+            position: positionValue,
+            zoom: isZoomSpecified ? zoom : current.zoom,
+            bearing: isBearingSpecified ? bearing : current.bearing,
+            tilt: isTiltSpecified ? tilt : current.tilt,
+            paddings: paddings,
+            visibleRegion: visibleRegion
+        )
+    }
+
     public func equals(other: MapCameraPositionProtocol) -> Bool {
         positionValue == GeoPoint.from(position: other.position) &&
             zoomEquals(other) &&
@@ -92,11 +124,12 @@ public final class MapCameraPosition: MapCameraPositionProtocol {
         paddings: MapPaddingsProtocol? = nil,
         visibleRegion: VisibleRegion? = nil
     ) -> MapCameraPosition {
+        // 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。
         MapCameraPosition(
             position: position ?? self.positionValue,
-            zoom: zoom ?? self.zoom,
-            bearing: bearing ?? self.bearing,
-            tilt: tilt ?? self.tilt,
+            zoom: zoom ?? (isZoomSpecified ? self.zoom : nil),
+            bearing: bearing ?? (isBearingSpecified ? self.bearing : nil),
+            tilt: tilt ?? (isTiltSpecified ? self.tilt : nil),
             paddings: paddings ?? self.paddings,
             visibleRegion: visibleRegion ?? self.visibleRegion
         )

Sources/MapConductorCore/map/MapViewState.swift

@@ -159,9 +159,9 @@ open class MapViewState<ActualMapDesignType>: ObservableObject, MapViewStateProt
     }
 
     open func moveCameraTo(cameraPosition: MapCameraPosition, durationMillis: Long? = 0) {
-        // カメラを渡されたらそのまま使う。「位置だけ動かして縮尺は保つ」は
-        // `moveCameraTo(position:)` のオーバーロードが担う。
-        let resolved = cameraPosition
+        // 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。
+        let resolved = cameraPosition.resolved(onto: storedCameraPosition)
         guard let controller = attachedMapController else {
             // まだ地図が無い。接続時に attachController がこの位置へ移動する。
             storedCameraPosition = resolved

Tests/MapConductorCoreTests/CameraPositionResolveTests.swift

@@ -0,0 +1,77 @@
+import XCTest
+
+@testable import MapConductorCore
+
+/// 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。
+final class CameraPositionResolveTests: XCTestCase {
+    private let tokyo = GeoPoint(latitude: 35.6812, longitude: 139.7671)
+    private let osaka = GeoPoint(latitude: 34.7025, longitude: 135.4959)
+
+    private var current: MapCameraPosition {
+        MapCameraPosition(position: tokyo, zoom: 12, bearing: 30, tilt: 45)
+    }
+
+    func testPositionOnlyKeepsEverythingElse() {
+        let resolved = MapCameraPosition(position: osaka).resolved(onto: current)
+        XCTAssertEqual(GeoPoint.from(position: resolved.position), osaka)
+        XCTAssertEqual(resolved.zoom, 12)
+        XCTAssertEqual(resolved.bearing, 30)
+        XCTAssertEqual(resolved.tilt, 45)
+    }
+
+    func testExplicitZeroIsHonoured() {
+        let resolved = MapCameraPosition(position: osaka, zoom: 0, bearing: 0, tilt: 0)
+            .resolved(onto: current)
+        XCTAssertEqual(resolved.zoom, 0)
+        XCTAssertEqual(resolved.bearing, 0)
+        XCTAssertEqual(resolved.tilt, 0)
+    }
+
+    func testEachPropertyIsInheritedOnItsOwn() {
+        let zoomOnly = MapCameraPosition(position: osaka, zoom: 0).resolved(onto: current)
+        XCTAssertEqual(zoomOnly.zoom, 0)
+        XCTAssertEqual(zoomOnly.bearing, 30)
+        XCTAssertEqual(zoomOnly.tilt, 45)
+
+        let bearingOnly = MapCameraPosition(position: osaka, bearing: 0).resolved(onto: current)
+        XCTAssertEqual(bearingOnly.zoom, 12)
+        XCTAssertEqual(bearingOnly.bearing, 0)
+        XCTAssertEqual(bearingOnly.tilt, 45)
+
+        let tiltOnly = MapCameraPosition(position: osaka, tilt: 0).resolved(onto: current)
+        XCTAssertEqual(tiltOnly.zoom, 12)
+        XCTAssertEqual(tiltOnly.bearing, 30)
+        XCTAssertEqual(tiltOnly.tilt, 0)
+    }
+
+    func testUnspecifiedReadsAsZeroBeforeResolving() {
+        let camera = MapCameraPosition(position: osaka)
+        XCTAssertEqual(camera.zoom, 0)
+        XCTAssertFalse(camera.isZoomSpecified)
+        XCTAssertFalse(camera.isBearingSpecified)
+        XCTAssertFalse(camera.isTiltSpecified)
+        XCTAssertTrue(MapCameraPosition.Default.isZoomSpecified)
+    }
+
+    func testCopyKeepsUnspecifiedUnlessGiven() {
+        let copied = MapCameraPosition(position: osaka).copy(position: tokyo)
+        XCTAssertFalse(copied.isZoomSpecified)
+
+        let withZoom = MapCameraPosition(position: osaka).copy(zoom: 0)
+        XCTAssertTrue(withZoom.isZoomSpecified)
+        XCTAssertFalse(withZoom.isBearingSpecified)
+    }
+
+    func testMapViewStateMergesUnsetPropertiesFromCurrentCamera() {
+        let state = MapViewState<Int>(initialCameraPosition: current)
+
+        state.moveCameraTo(cameraPosition: MapCameraPosition(position: osaka, bearing: 0))
+        XCTAssertEqual(state.cameraPosition.zoom, 12)
+        XCTAssertEqual(state.cameraPosition.bearing, 0)
+        XCTAssertEqual(state.cameraPosition.tilt, 45)
+
+        state.moveCameraTo(cameraPosition: MapCameraPosition(position: osaka, zoom: 0))
+        XCTAssertEqual(state.cameraPosition.zoom, 0)
+    }
+}

api/MapConductorCore.api.swift

@@ -1204,7 +1204,11 @@ final public class MapCameraPosition : MapConductorCore::MapCameraPositionProtoc
   final public let tilt: Swift::Double
   final public let paddings: (any MapConductorCore::MapPaddingsProtocol)?
   final public let visibleRegion: MapConductorCore::VisibleRegion?
-  public init(position: any MapConductorCore::GeoPointProtocol, zoom: Swift::Double = 0.0, bearing: Swift::Double = 0.0, tilt: Swift::Double = 0.0, paddings: (any MapConductorCore::MapPaddingsProtocol)? = MapPaddings.Zeros, visibleRegion: MapConductorCore::VisibleRegion? = nil)
+  final public let isZoomSpecified: Swift::Bool
+  final public let isBearingSpecified: Swift::Bool
+  final public let isTiltSpecified: Swift::Bool
+  public init(position: any MapConductorCore::GeoPointProtocol, zoom: Swift::Double? = nil, bearing: Swift::Double? = nil, tilt: Swift::Double? = nil, paddings: (any MapConductorCore::MapPaddingsProtocol)? = MapPaddings.Zeros, visibleRegion: MapConductorCore::VisibleRegion? = nil)
+  final public func resolved(onto current: any MapConductorCore::MapCameraPositionProtocol) -> MapConductorCore::MapCameraPosition
   final public func equals(other: any MapConductorCore::MapCameraPositionProtocol) -> Swift::Bool
   final public func copy(position: (any MapConductorCore::GeoPointProtocol)? = nil, zoom: Swift::Double? = nil, bearing: Swift::Double? = nil, tilt: Swift::Double? = nil, paddings: (any MapConductorCore::MapPaddingsProtocol)? = nil, visibleRegion: MapConductorCore::VisibleRegion? = nil) -> MapConductorCore::MapCameraPosition
   final public func hashCode() -> Swift::Int