Create planar and geodetic buffers

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
// Copyright 2022 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 SwiftUI
import ArcGIS

struct CreatePlanarAndGeodeticBuffersView: View {
    /// A Boolean value indicating whether to show options.
    @State private var isShowingOptions = false

    /// The radius to pass into the buffer functions.
    @State private var bufferDistance = Measurement(value: 500, unit: UnitLength.miles)

    /// The possible radii for buffers in miles.
    private let bufferRadii = Measurement.rMin...Measurement.rMax

    /// A map with a topographic basemap style.
    @StateObject private var map = Map(basemapStyle: .arcGISTopographic)

    /// The graphics overlay for displaying the geometries created via a geodetic buffer around the tap point.
    /// Contains graphics with green fill and black outline symbols.
    @StateObject private var geodeticOverlay = makeGeodeticOverlay()

    /// The graphics overlay for displaying the geometries created via a planar buffer around the tap point.
    /// Contains graphics with red fill and black outline symbols.
    /// The red fill symbol appears brown when blended with the geodetic overlay.
    @StateObject private var planarOverlay = makePlanarOverlay()

    /// The graphics overlay for displaying the location of the tap point.
    /// Contains graphics with white cross symbols.
    @StateObject private var tapLocationsOverlay = makeTapLocationsOverlay()

    /// The graphics overlays used in this sample.
    private var graphicsOverlays: [GraphicsOverlay] {
        return [geodeticOverlay, planarOverlay, tapLocationsOverlay]
    }

    /// Creates a graphics overlay for the geodetic overlay.
    private static func makeGeodeticOverlay() -> GraphicsOverlay {
        let overlay = GraphicsOverlay()
        let outlineSymbol = SimpleLineSymbol(style: .solid, color: .black, width: 2)
        let fillSymbol = SimpleFillSymbol(style: .solid, color: .green, outline: outlineSymbol)
        overlay.renderer = SimpleRenderer(symbol: fillSymbol)
        overlay.opacity = 0.5
        return overlay
    }

    /// Creates a graphics overlay for the planar overlay.
    private static func makePlanarOverlay() -> GraphicsOverlay {
        let overlay = GraphicsOverlay()
        let outlineSymbol = SimpleLineSymbol(style: .solid, color: .black, width: 2)
        let fillSymbol = SimpleFillSymbol(style: .solid, color: .red, outline: outlineSymbol)
        overlay.renderer = SimpleRenderer(symbol: fillSymbol)
        overlay.opacity = 0.5
        return overlay
    }

    /// Creates a graphics overlay for the tap locations overlay.
    private static func makeTapLocationsOverlay() -> GraphicsOverlay {
        let overlay = GraphicsOverlay()
        let symbol = SimpleMarkerSymbol(style: .cross, color: .white, size: 14)
        overlay.renderer = SimpleRenderer(symbol: symbol)
        return overlay
    }

    /// Adds a buffer at a given point.
    private func addBuffer(at point: Point) {
        // Converts the buffer distance to meters.
        let bufferRadiusInMeters = bufferDistance.converted(to: .meters).value

        // Creates the geometry for the map point, buffered by the given
        // distance in respect to the geodetic spatial reference system
        // (the 3D representation of the Earth).
        if let geodesicGeometry = GeometryEngine.geodeticBuffer(
            around: point,
            distance: bufferRadiusInMeters,
            distanceUnit: .meters,
            maxDeviation: .nan,
            curveType: .geodesic
        ) {
            // Creates and adds a graphic with the geodesic geometry
            // to the geodetic overlay.
            geodeticOverlay.addGraphic(Graphic(geometry: geodesicGeometry))
        }

        // Creates the geometry for the map point, buffered by the given
        // distance in respect to the projected map spatial reference system.
        if let planarGeometry = GeometryEngine.buffer(
            around: point,
            distance: bufferRadiusInMeters
        ) {
            // Creates and adds a graphic with the planar geometry
            // to the planar overlay.
            planarOverlay.addGraphic(Graphic(geometry: planarGeometry))
        }

        // Creates and adds a graphic symbolizing the tap location
        // to the tap locations overlay.
        tapLocationsOverlay.addGraphic(Graphic(geometry: point))
    }

    /// Removes all graphics from all graphics overlays.
    private func clearGraphics() {
        graphicsOverlays.forEach { $0.removeAllGraphics() }
    }

    var body: some View {
        VStack {
            // Creates a map view with graphics overlays.
            MapView(map: map, graphicsOverlays: graphicsOverlays)
                .onSingleTapGesture { _, mapPoint in
                    // Adds a buffer at the given map point.
                    addBuffer(at: mapPoint)
                }

            if isShowingOptions {
                VStack {
                    Slider(value: $bufferDistance.value, in: bufferRadii.doubleRange) {
                        Text("Buffer Radius")
                    } minimumValueLabel: {
                        Text(bufferRadii.lowerBound, format: .measurement(width: .narrow))
                    } maximumValueLabel: {
                        Text(bufferRadii.upperBound, format: .measurement(width: .narrow))
                    }

                    Text("Buffer radius: \(bufferDistance, format: .measurement(width: .abbreviated))")
                }
                .padding([.horizontal, .top])
            }

            HStack {
                Spacer()
                Toggle(isOn: $isShowingOptions.animation(.spring())) {
                    Text("Options")
                }
                .toggleStyle(.button)
                Spacer()
                Button("Clear All") {
                    clearGraphics()
                }
                Spacer()
            }
            .padding()
        }
    }
}

private extension ClosedRange where Bound == Measurement<UnitLength> {
    /// The measurement's values as a closed range of doubles.
    var doubleRange: ClosedRange<Double> { self.lowerBound.value...self.upperBound.value }
}

private extension Measurement where UnitType == UnitLength {
    /// The minimum radius.
    static var rMin: Self { Measurement(value: 200, unit: UnitLength.miles) }
    /// The maximum radius.
    static var rMax: Self { Measurement(value: 2_000, unit: UnitLength.miles) }
}