Stack overlays in one band order, whatever order they arrive in

Sources/MapConductorForMapbox/MapboxOverlayStacking.swift

@@ -0,0 +1,37 @@
+import Foundation
+import MapboxMaps
+@_spi(MapConductorDriver) import MapConductorCore
+
+/// オーバーレイのレイヤを、重なり順の帯（``OverlayBand``）の位置へ置くための `LayerPosition`。
+///
+/// 下から ラスター < グラウンドイメージ < ポリゴン < サークル < ポリライン < マーカー。
+/// 追加した順・送り直した順・デザイン変更の後の作り直しの順に左右されない。
+/// 以前は各描画担当が `addLayer(_:)`（一番上に積む）で足していたので、後から足したもの
+/// （clearOverlays の後に送り直したグラウンドイメージなど）が上に来ていた。
+///
+/// ラスターだけはベースマップのラベルの下に置く（ラベルを覆わないため。従来どおり）。
+/// Standard スタイルのようにベースマップが import でトップレベルのレイヤを持たないときは
+/// 天井が見つからず、ほかのオーバーレイより下という帯の条件だけで置く。
+enum MapboxOverlayStacking {
+    static func position(
+        for key: OverlayStackKey,
+        in mapboxMap: MapboxMap,
+        excluding layerId: String? = nil,
+        rasterZIndex: [String: Int] = [:]
+    ) -> LayerPosition {
+        let layers = mapboxMap.allLayerIdentifiers.filter { $0.id != layerId }
+        let keys: [OverlayStackKey?] = layers.map { info in
+            guard let band = OverlayStacking.band(ofStyleLayerId: info.id) else { return nil }
+            return OverlayStackKey(band, zIndex: band == .rasterLayer ? (rasterZIndex[info.id] ?? 0) : 0)
+        }
+        let ceiling = key.band == .rasterLayer
+            ? layers.firstIndex { $0.type == .symbol && OverlayStacking.band(ofStyleLayerId: $0.id) == nil }
+            : nil
+        let index = OverlayStacking.insertionIndex(for: key, among: keys, ceiling: ceiling)
+        return index >= layers.count ? .default : .below(layers[index].id)
+    }
+
+    static func add(_ layer: any Layer, _ key: OverlayStackKey, to mapboxMap: MapboxMap) {
+        try? mapboxMap.addLayer(layer, layerPosition: position(for: key, in: mapboxMap))
+    }
+}

Sources/MapConductorForMapbox/circle/CircleLayer.swift

@@ -1,5 +1,6 @@
 import Foundation
 import MapboxMaps
+@_spi(MapConductorDriver) import MapConductorCore
 
 /// Draws circles as "fill (FillLayer) + stroke (LineLayer)".
 ///
@@ -46,7 +47,7 @@ final class CircleLayer {
         if !mapboxMap.layerExists(withId: layerId) {
             var fillLayer = FillLayer(id: layerId, source: sourceId)
             fillLayer.fillColor = .expression(Exp(.toColor) { Exp(.get) { Prop.fillColor } })
-            try? mapboxMap.addLayer(fillLayer)
+            MapboxOverlayStacking.add(fillLayer, OverlayStackKey(.circle), to: mapboxMap)
         }
 
         if !mapboxMap.layerExists(withId: strokeLayerId) {

Sources/MapConductorForMapbox/groundimage/MapboxGroundImageOverlayRenderer.swift

@@ -1,6 +1,6 @@
 import Foundation
 import MapboxMaps
-import MapConductorCore
+@_spi(MapConductorDriver) import MapConductorCore
 import UIKit
 
 @MainActor
@@ -115,7 +115,7 @@ final class MapboxGroundImageOverlayRenderer: AbstractGroundImageOverlayRenderer
 
         var layer = RasterLayer(id: layerId, source: sourceId)
         layer.rasterOpacity = .constant(opacity.clampedOpacity)
-        try? mapboxMap.addLayer(layer)
+        MapboxOverlayStacking.add(layer, OverlayStackKey(.groundImage), to: mapboxMap)
     }
 
     private func removeSourceAndLayerIfExists(mapboxMap: MapboxMap, sourceId: String, layerId: String) {

Sources/MapConductorForMapbox/marker/MapboxMarkerController.swift

@@ -359,7 +359,8 @@ final class MapboxMarkerController: AbstractMarkerController<Feature, MapboxMark
         try? mapboxMap.addSource(source)
 
         let layer = RasterLayer(id: layerId, source: sourceId)
-        try? mapboxMap.addLayer(layer)
+        // マーカーのタイルはマーカーと同じ帯。
+        MapboxOverlayStacking.add(layer, OverlayStackKey(.marker), to: mapboxMap)
     }
 
     private func subscribeToMarker(_ state: MarkerState) {

Sources/MapConductorForMapbox/marker/MarkerLayer.swift

@@ -1,5 +1,6 @@
 import Foundation
 import MapboxMaps
+@_spi(MapConductorDriver) import MapConductorCore
 
 final class MarkerLayer {
     enum Prop {
@@ -68,7 +69,7 @@ final class MarkerLayer {
                 Double(1)
             }
         )
-        try? mapboxMap.addLayer(layer)
+        MapboxOverlayStacking.add(layer, OverlayStackKey(.marker), to: mapboxMap)
     }
 
     func setFeatures(_ features: [Feature], mapboxMap: MapboxMap) {

Sources/MapConductorForMapbox/polygon/PolygonLayer.swift

@@ -1,5 +1,6 @@
 import Foundation
 import MapboxMaps
+@_spi(MapConductorDriver) import MapConductorCore
 
 final class PolygonLayer {
     enum Prop {
@@ -40,7 +41,7 @@ final class PolygonLayer {
         if !mapboxMap.layerExists(withId: fillLayerId) {
             var fillLayer = FillLayer(id: fillLayerId, source: sourceId)
             fillLayer.fillColor = .expression(Exp(.toColor) { Exp(.get) { Prop.fillColor } })
-            try? mapboxMap.addLayer(fillLayer)
+            MapboxOverlayStacking.add(fillLayer, OverlayStackKey(.polygon), to: mapboxMap)
         }
 
         if !mapboxMap.layerExists(withId: lineLayerId) {
@@ -49,7 +50,7 @@ final class PolygonLayer {
             lineLayer.lineWidth = .expression(Exp(.toNumber) { Exp(.get) { Prop.strokeWidth } })
             lineLayer.lineJoin = .constant(.round)
             lineLayer.lineCap = .constant(.round)
-            try? mapboxMap.addLayer(lineLayer)
+            MapboxOverlayStacking.add(lineLayer, OverlayStackKey(.polygon), to: mapboxMap)
         }
     }
 

Sources/MapConductorForMapbox/polyline/PolylineLayer.swift

@@ -1,5 +1,6 @@
 import Foundation
 import MapboxMaps
+@_spi(MapConductorDriver) import MapConductorCore
 
 final class PolylineLayer {
     enum Prop {
@@ -40,7 +41,7 @@ final class PolylineLayer {
             layer.lineWidth = .expression(Exp(.toNumber) { Exp(.get) { Prop.strokeWidth } })
             layer.lineJoin = .constant(.round)
             layer.lineCap = .constant(.round)
-            try? mapboxMap.addLayer(layer)
+            MapboxOverlayStacking.add(layer, OverlayStackKey(.polyline), to: mapboxMap)
         }
     }
 

Sources/MapConductorForMapbox/raster/MapboxRasterLayerOverlayRenderer.swift

@@ -1,5 +1,5 @@
 import MapboxMaps
-import MapConductorCore
+@_spi(MapConductorDriver) import MapConductorCore
 
 @MainActor
 final class MapboxRasterLayerOverlayRenderer: AbstractRasterLayerOverlayRenderer<MapboxRasterLayer> {
@@ -45,7 +45,16 @@ final class MapboxRasterLayerOverlayRenderer: AbstractRasterLayerOverlayRenderer
             NSLog("[MapConductor] RasterLayer debug mode: id=%@", current.state.id)
         }
         if finger.zIndex != prevFinger.zIndex {
-            try? mapboxMap.moveLayer(withId: layer.layerId, to: current.state.zIndex > 0 ? .at(current.state.zIndex) : .default)
+            zIndexByLayerId[layer.layerId] = current.state.zIndex
+            try? mapboxMap.moveLayer(
+                withId: layer.layerId,
+                to: MapboxOverlayStacking.position(
+                    for: OverlayStacking.rasterKey(stateId: current.state.id, zIndex: current.state.zIndex),
+                    in: mapboxMap,
+                    excluding: layer.layerId,
+                    rasterZIndex: zIndexByLayerId
+                )
+            )
         }
         if finger.opacity != prevFinger.opacity {
             try? mapboxMap.updateLayer(withId: layer.layerId, type: MapboxMaps.RasterLayer.self) { l in
@@ -113,28 +122,22 @@ final class MapboxRasterLayerOverlayRenderer: AbstractRasterLayerOverlayRenderer
         try? mapboxMap.addLayer(layer, layerPosition: layerPosition)
     }
 
-    /// A raster overlay goes above the basemap's geometry but **below its
-    /// labels**.
+    /// 帯の順の位置（ラスターの帯の中は zIndex、ベースマップのラベルの下）。``MapboxOverlayStacking`` を参照。
     ///
-    /// Added at the top of the style instead, it covers the place names, road
-    /// names and shields the backend draws -- a vector tile layer's own roads
-    /// run straight through them, which is what "the labels are under the
-    /// lines" looks like. Every raster overlay we add has the same problem, so
-    /// the rule lives here rather than in each of them.
-    ///
-    /// An explicit zIndex still wins: a caller that has said where the layer
-    /// goes has said it for a reason. Our own layers are skipped when looking
-    /// for the anchor -- markers are a symbol layer too, and anchoring to them
-    /// would put the raster back above the labels.
+    /// 以前は `zIndex > 0` をスタイル全体の生の添字（`.at(zIndex)`）として使っていて、
+    /// ベースマップのレイヤの間（多くは地図の下）へ入っていた。
     private func layerPosition(for state: RasterLayerState, mapboxMap: MapboxMap) -> LayerPosition {
-        if state.zIndex > 0 { return .at(state.zIndex) }
-        let anchor = mapboxMap.allLayerIdentifiers.first {
-            $0.type == .symbol && !$0.id.hasPrefix("mapconductor-")
-        }
-        guard let anchor else { return .default }
-        return .below(anchor.id)
+        zIndexByLayerId["mapconductor-raster-layer-\(state.id)"] = state.zIndex
+        return MapboxOverlayStacking.position(
+            for: OverlayStacking.rasterKey(stateId: state.id, zIndex: state.zIndex),
+            in: mapboxMap,
+            rasterZIndex: zIndexByLayerId
+        )
     }
 
+    /// 差し込み位置を決めるための、載せているラスターの zIndex（スタイルのレイヤは zIndex を持たない）。
+    private var zIndexByLayerId: [String: Int] = [:]
+
     private func removeIfExists(mapboxMap: MapboxMap, sourceId: String, layerId: String) {
         if mapboxMap.layerExists(withId: layerId) { try? mapboxMap.removeLayer(withId: layerId) }
         if mapboxMap.sourceExists(withId: sourceId) { try? mapboxMap.removeSource(withId: sourceId) }