Add DynamicRendererMapOverlay

Sources/Overlays/DynamicRendererMapOverlay.swift

@@ -0,0 +1,181 @@
+//
+//  DynamicRendererMapOverlay.swift
+//  Map
+//
+//  Created by Paul Kraft on 26.04.22.
+//
+
+#if !os(watchOS)
+
+import Combine
+import MapKit
+
+public struct DynamicRendererMapOverlay: MapOverlay {
+
+    // MARK: Nested Types
+
+    public struct Update {
+
+        // MARK: Stored Properties
+
+        let coordinate: CLLocationCoordinate2D?
+        let boundingMapRect: MKMapRect?
+        let displayRequest: DisplayRequest?
+
+        // MARK: Initialization
+
+        public init(
+            coordinate: CLLocationCoordinate2D? = nil, 
+            boundingMapRect: MKMapRect? = nil,
+            displayRequest: DisplayRequest? = nil
+        ) {
+            self.coordinate = coordinate
+            self.boundingMapRect = boundingMapRect
+            self.displayRequest = displayRequest
+        }
+
+    }
+
+    public struct DisplayRequest {
+
+        // MARK: Stored Properties
+
+        let mapRect: MKMapRect?
+        let zoomScale: MKZoomScale?
+
+        // MARK: Initialization
+
+        public init(mapRect: MKMapRect? = nil) {
+            self.mapRect = mapRect
+            self.zoomScale = nil
+        }
+
+        public init(mapRect: MKMapRect, zoomScale: MKZoomScale?) {
+            self.mapRect = mapRect
+            self.zoomScale = zoomScale
+        }
+
+    }
+
+    class Overlay: NSObject, MKOverlay {
+
+        // MARK: Stored Properties
+
+        @objc dynamic var coordinate: CLLocationCoordinate2D
+        @objc dynamic var boundingMapRect: MKMapRect
+
+        // MARK: Initialization
+
+        init(coordinate: CLLocationCoordinate2D, boundingMapRect: MKMapRect) {
+            self.coordinate = coordinate
+            self.boundingMapRect = boundingMapRect
+        }
+
+    }
+
+    // MARK: Stored Properties
+
+    public let overlay: MKOverlay
+    public let level: MKOverlayLevel?
+    private let updatePublisher: AnyPublisher<Update, Never>
+    private let canDraw: ((MKMapRect, MKZoomScale) -> Bool)?
+    private let draw: (MKMapRect, MKZoomScale, CGContext) -> Void
+
+    // MARK: Initialization
+
+    public init<P: Publisher>(
+        coordinate: CLLocationCoordinate2D,
+        boundingMapRect: MKMapRect,
+        level: MKOverlayLevel? = nil,
+        updates: P,
+        canDraw: ((MKMapRect, MKZoomScale) -> Bool)? = nil,
+        draw: @escaping (MKMapRect, MKZoomScale, CGContext) -> Void
+    ) where P.Output == Update, P.Failure == Never {
+
+        self.overlay = Overlay(coordinate: coordinate, boundingMapRect: boundingMapRect)
+        self.level = level
+        self.updatePublisher = updates.eraseToAnyPublisher()
+        self.canDraw = canDraw
+        self.draw = draw
+    }
+
+
+    public func renderer(for mapView: MKMapView) -> MKOverlayRenderer {
+        guard let overlay = overlay as? Overlay else {
+            assertionFailure("DynamicRendererMapOverlay does not support custom MKOverlay classes.")
+            return MKOverlayRenderer(overlay: overlay)
+        }
+        return DynamicMapRenderer(
+            overlay: overlay,
+            updatePublisher: updatePublisher,
+            canDraw: canDraw,
+            draw: draw
+        )
+    }
+
+}
+
+private class DynamicMapRenderer: MKOverlayRenderer {
+
+    // MARK: Stored Properties
+
+    private let _canDraw: ((MKMapRect, MKZoomScale) -> Bool)?
+    private let _draw: (MKMapRect, MKZoomScale, CGContext) -> Void
+    private var cancellables = Set<AnyCancellable>()
+
+    // MARK: Initialization
+
+    init(overlay: DynamicRendererMapOverlay.Overlay,
+         updatePublisher: AnyPublisher<DynamicRendererMapOverlay.Update, Never>,
+         canDraw: ((MKMapRect, MKZoomScale) -> Bool)?,
+         draw: @escaping (MKMapRect, MKZoomScale, CGContext) -> Void) {
+
+        self._canDraw = canDraw
+        self._draw = draw
+        super.init(overlay: overlay)
+
+        updatePublisher
+            .receive(on: DispatchQueue.main)
+            .sink { [unowned self] in self.handle($0) }
+            .store(in: &cancellables)
+    }
+
+    // MARK: Overrides
+
+    override func canDraw(_ mapRect: MKMapRect, zoomScale: MKZoomScale) -> Bool {
+        _canDraw?(mapRect, zoomScale) ?? super.canDraw(mapRect, zoomScale: zoomScale)
+    }
+
+    override func draw(_ mapRect: MKMapRect, zoomScale: MKZoomScale, in context: CGContext) {
+        _draw(mapRect, zoomScale, context)
+    }
+
+    // MARK: Helpers
+
+    private func handle(_ update: DynamicRendererMapOverlay.Update) {
+        let typedOverlay = overlay as? DynamicRendererMapOverlay.Overlay
+
+        if let coordinate = update.coordinate {
+            typedOverlay?.coordinate = coordinate
+        }
+
+        if let boundingMapRect = update.boundingMapRect {
+            typedOverlay?.boundingMapRect = boundingMapRect
+        }
+
+        if let request = update.displayRequest {
+            guard let mapRect = request.mapRect else {
+                setNeedsDisplay()
+                return
+            }
+            guard let zoomScale = request.zoomScale else {
+                setNeedsDisplay(mapRect)
+                return
+            }
+            setNeedsDisplay(mapRect, zoomScale: zoomScale)
+        }
+    }
+
+}
+
+#endif