Set reference scale

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// Copyright 2024 Esri
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import ArcGIS
import SwiftUI

struct SetReferenceScaleView: View {
    /// A map of the "Isle of Wight" portal item.
    @State private var map: Map = {
        // Creates the map from a portal item on ArcGIS Online.
        let portalItem = PortalItem(portal: .arcGISOnline(connection: .anonymous), id: .isleOfWight)
        let map = Map(item: portalItem)

        // Sets the initial reference scale for the map.
        map.referenceScale = 250_000
        return map
    }()

    /// The scale of the map view.
    @State private var mapScale: Double = .nan

    /// A Boolean value indicating whether the map settings popover is presented.
    @State private var settingsPopoverIsPresented = false

    var body: some View {
        MapViewReader { mapViewProxy in
            MapView(map: map)
                .onScaleChanged { mapScale = $0 }
                .toolbar {
                    ToolbarItem(placement: .bottomBar) {
                        Button("Map Settings") {
                            settingsPopoverIsPresented = true
                        }
                        .popover(isPresented: $settingsPopoverIsPresented) { [mapScale] in
                            MapSettingsView(map: map, mapScale: mapScale) { scale in
                                // Sets the map's scale to the selected reference scale
                                // when the "Set to Reference Scale" button is tapped.
                                Task {
                                    await mapViewProxy.setViewpointScale(scale)
                                }
                            }
                            .presentationDetents([.fraction(0.5)])
                            .frame(idealWidth: 320, idealHeight: 380)
                        }
                    }
                }
        }
    }
}

private extension SetReferenceScaleView {
    /// The view containing settings controls for a map.
    struct MapSettingsView: View {
        /// The map.
        let map: Map

        /// A binding to the scale of the map.
        let mapScale: Double

        /// The action to set the map scale, i.e, when the "Set to Reference Scale" button is pressed.
        let setMapScaleAction: (_ scale: Double) -> Void

        /// The action to dismiss the view.
        @Environment(\.dismiss) private var dismiss

        /// The reference scale option selected in the picker.
        @State private var selectedReferenceScale: Double = 250_000

        /// The options for the reference scale picker
        private let referenceScaleOptions: [Double] = [500_000, 250_000, 100_000, 50_000]

        var body: some View {
            NavigationStack {
                Form {
                    Section {
                        Picker("Reference Scale", selection: $selectedReferenceScale) {
                            ForEach(referenceScaleOptions, id: \.self) { option in
                                Text("1:\(option, format: .number.rounded(increment: 1))")
                            }
                        }
                        .onChange(of: selectedReferenceScale) { map.referenceScale = $0 }

                        NavigationLink("Layers") {
                            List(map.operationalLayers as! [FeatureLayer], id: \.id) { layer in
                                ScalesSymbolsToggle(layer: layer)
                            }
                            .navigationTitle("Layers")
                            .navigationBarTitleDisplayMode(.inline)
                            .toolbar {
                                ToolbarItem(placement: .confirmationAction) {
                                    Button("Done") { dismiss() }
                                }
                            }
                        }
                    } footer: {
                        Text("Selected layers will scale according to the reference scale.")
                    }

                    Section {
                        LabeledContent("Map Scale") {
                            Text("1:\(mapScale, format: .number.rounded(increment: 1))")
                        }

                        Button("Set to Reference Scale") {
                            setMapScaleAction(selectedReferenceScale)
                        }
                        .frame(maxWidth: .infinity)
                        .disabled(mapScale == selectedReferenceScale)
                    }
                }
                .navigationTitle("Map Settings")
                .navigationBarTitleDisplayMode(.inline)
                .toolbar {
                    ToolbarItem(placement: .confirmationAction) {
                        Button("Done") { dismiss() }
                    }
                }
            }
            .onAppear {
                selectedReferenceScale = map.referenceScale!
            }
        }
    }

    /// A control that toggles the `scalesSymbols` property of a feature layer.
    struct ScalesSymbolsToggle: View {
        /// The feature layer.
        let layer: FeatureLayer

        /// A Boolean value indicating whether layer’s symbols and labels honor the map’s reference scale.
        @State private var layerScalesSymbol = false

        var body: some View {
            Toggle(layer.name, isOn: $layerScalesSymbol)
                .onChange(of: layerScalesSymbol) { layer.scalesSymbols = $0 }
                .onAppear { layerScalesSymbol = layer.scalesSymbols }
        }
    }
}

private extension PortalItem.ID {
    /// The ID for the "Isle of Wight" portal item on ArcGIS Online.
    static var isleOfWight: Self { Self("3953413f3bd34e53a42bf70f2937a408")! }
}

#Preview {
    NavigationStack {
        SetReferenceScaleView()
    }
}