[FOSS4G 2023 Japan] スマホアプリの地図表示における第三の選択肢 MapLibre Native を使ってみる

MapLibreにおいても、スマホアプリのSDKが提供されています。
この発表では、オープンソースのスマホアプリ用地図ライブラリ MapLibre Native で、GeoJSON のジオメトリを表示するサンプルを紹介します。

サンプルアプリのソースコード
https://github.com/k15015kk/TXMapSample

FOSS4G 2023 Japan コアデイ
https://www.osgeo.jp/events/foss4g-2023/foss4g-2023-japan-at-fukui/foss4g-coreday

Transcript

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16. 4XJGU6*Ͱ.BQ7JFXΛ࡞੒ makeUIViewʹ஍ਤදࣔͷॳظઃఆΛͭͭ͠MGLMapViewΛฦ͢ MapView.swift func makeUIView(context: Context) -> some UIView { // 地図のスタイルを定義 let styleURL = URL(string: "https://api.maptiler.com/maps/jp-mierune-gray/style.json?key=\(mapTilerAPIKey)") // MGLMapViewを定義 let mapView = MGLMapView(frame: .zero, styleURL: styleURL) // AutoLayoutの設定を定義 mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight] // Mapboxのロゴを消す mapView.logoView.isHidden = true // TXの路線の重⼼を地図の中⼼に設定 mapView.setCenter( CLLocationCoordinate2D( latitude: 35.894930906699322, longitude: 139.937432307518321 ), zoomLevel: 9.2, animated: false ) // デリゲート（処理の委任先）定義 mapView.delegate = context.coordinator return mapView } .BQ5JMFSͷ஍ਤΛදࣔ
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17. 4XJGU6*Ͱ.BQ7JFXΛ࡞੒ CoordinatorΛఆٛͯ͠஍ਤૢ࡞ʹؔ͢ΔॲཧΛهࡌ MapView.swift func makeCoordinator() -> MainMapView.Coordinator { Coordinator(self) } class Coordinator: NSObject, MGLMapViewDelegate { var control: MapView init(_ control: MapView) { self.control = control } // マップが表⽰されたあとの処理 func mapViewDidFinishLoadingMap(_ mapView: MGLMapView) { } } (class Coordinatorは内部クラス)
18. 4XJGU6*Ͱ.BQ7JFXΛ࡞੒ UIViewRepresentableͷ౎߹ͰۭͷupdateUIViewΛఆٛ MapView.swift func updateUIView(_ uiView: UIViewType, context: Context) { }
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23. (FP+40/ΛಡΈࠐΉؔ਺Λ࡞੒ MapView.swift func loadGeoJSONData(resourceName: String) async -> Data { guard let jsonURL = Bundle.main.url( forResource: resourceName, withExtension: "geojson" ) else { preconditionFailure("GeoJSONファイルの読み込みに失敗しました") } guard let jsonData = try? Data(contentsOf: jsonURL) else { preconditionFailure("GeoJSONファイルのパースに失敗しました") } return jsonData } Ҿ਺ͰϑΝΠϧ໊Λड͚औΔΑ͏ʹͯ͠൚༻తͳؔ਺ʹ͠·͢
24. ઢܗΛඳը͢Δؔ਺Λ࡞੒ MapView.swift func drawRailway(_ mapView: MGLMapView, geoJson: Data) { // ここに描画に必要な定義をします } guard let style = mapView.style else { return } // GeoJSONデータからShapeを⽣成 guard let shapeFromGeoJson = try? MGLShape(data: geoJson, encoding: String.Encoding.utf8.rawValue) else { fatalError("MGLShapeの⽣成ができませんでした") } func drawRailway .BQ-JCSFͷ7JFX (FP+40/ͷ%BUB
25. ઢܗΛඳը͢Δؔ਺Λ࡞੒ // 表⽰ソースを定義 let shapeSource = MGLShapeSource(identifier: "railway-source", shape: shapeFromGeoJson, options: nil) style.addSource(shapeSource) // レイヤーを定義 let lineLayer = MGLLineStyleLayer(identifier: "railway-line-style", source: shapeSource) // 始点・終点の形 lineLayer.lineJoin = NSExpression(forConstantValue: "round") lineLayer.lineCap = NSExpression(forConstantValue: "round") // 線の⾊ lineLayer.lineColor = NSExpression(forConstantValue: UIColor.orange) // 線の幅 // ズームレベルに応じて幅を変えたい場合 mgl_interpolate:withCurveType:parameters:stops: を使って定義 lineLayer.lineWidth = NSExpression( format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", [10: 2.0, 18: 8.0] ) style.addLayer(lineLayer) func drawRailway /4&YQSFTTJPOͰఆٛ͢Δ͜ͱ͕ଟ͍
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26. ࣮ࡍʹඳըؔ਺Λݺͼग़͢ MapView.swift class Coordinator: NSObject, MGLMapViewDelegate { // 省略 func mapViewDidFinishLoadingMap(_ mapView: MGLMapView) { self.control.drawRailwayAndStation(mapView) } } func drawRailwayAndStation(_ mapView: MGLMapView) { Task { let railwayData = await loadGeoJSONData(resourceName: "TX_Railway") await MainActor.run { drawRailway(mapView, geoJson: railwayData) } } } ௥ه
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30. Ӻͷ఺ͱӺ໊Λඳը͢Δؔ਺Λ࡞੒ func drawStation(_ mapView: MGLMapView, geoJson: Data) { // GeoJSONをshapeデータに変換（省略） // MGLShapeSourceを定義してstyleにSourceを追加（省略） // 駅の場所をCircleStyleに表⽰ let circleLayer = MGLCircleStyleLayer(identifier: "station-circle-style", source: shapeSoruce) circleLayer.circleColor = NSExpression(forConstantValue: UIColor.orange) circleLayer.circleRadius = NSExpression( format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)", [10: 4.0, 18: 16.0] ) style.addLayer(circleLayer) // 駅名をSymbolStyleLayerで表⽰する let shapeLayer = MGLSymbolStyleLayer(identifier: "station-symbol-style", source: shapeSoruce) shapeLayer.text = NSExpression(forKeyPath: "N05_011") shapeLayer.textColor = NSExpression(forConstantValue: UIColor.white) shapeLayer.textTranslation = NSExpression(forConstantValue: NSValue(cgVector: CGVector(dx: -4, dy: -4))) shapeLayer.textFontNames = NSExpression(forConstantValue: ["HiraginoSans-W6"]) shapeLayer.textFontSize = NSExpression(forConstantValue: 12.0) shapeLayer.textIgnoresPlacement = NSExpression(forConstantValue: true) shapeLayer.textJustification = NSExpression(forConstantValue: "right") shapeLayer.textAnchor = NSExpression(forConstantValue: "bottom-right") shapeLayer.textHaloColor = NSExpression(forConstantValue: UIColor.black) shapeLayer.textHaloWidth = NSExpression(forConstantValue: 1.0) style.addLayer(shapeLayer) } MapView.swift ςΩετʹԑऔΓΛ͚ͭΔ ԁͷඳը͸.(-$JSDMF4UZMF-BZFSΛར༻ ςΩετͷඳը͸.(-4ZNCPM4UZMF-BZFSΛར༻
31. ࣮ࡍʹඳըؔ਺Λݺͼग़͢ MapView.swift class Coordinator: NSObject, MGLMapViewDelegate { // 省略 func mapViewDidFinishLoadingMap(_ mapView: MGLMapView) { self.control.drawRailwayAndStation(mapView) } } func drawRailwayAndStation(_ mapView: MGLMapView) { Task { let railwayData = await loadGeoJSONData(resourceName: "TX_Railway") let stationData = await loadGeoJSONData(resourceName: "TX_Station") await MainActor.run { drawRailway(mapView, geoJson: railwayData) drawStation(mapView, geoJson: stationData) } } } ௥ه ௥ه
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35. ۠ࢢொଜϙϦΰϯΛඳը͢Δؔ਺Λ࡞੒ func drawMunicipality(_ mapView: MGLMapView, geoJson: Data) { // GeoJSONをshapeデータに変換（省略） // MGLShapeSourceを定義してstyleにSourceを追加（省略） // 市町村ポリゴンのスタイルを定義 let fillStyleLayer = MGLFillStyleLayer(identifier: "municipality-fill-style", source: shapeSource) fillStyleLayer.fillColor = NSExpression( format: "MGL_MATCH(N03_001, '東京都', %@, '埼⽟県', %@, '千葉県', %@, '茨城県', %@, %@)", UIColor.red, UIColor.yellow, UIColor.green, UIColor.blue, UIColor.black ) fillStyleLayer.fillOpacity = NSExpression(forConstantValue: 0.2) style.addLayer(fillStyleLayer) // ポリゴンの輪郭線スタイルを定義 let lineLayer = MGLLineStyleLayer(identifier: "municipality-line-style", source: shapeSource) lineLayer.lineWidth = NSExpression(forConstantValue: 1.0) lineLayer.lineColor = NSExpression(forConstantValue: UIColor.black) style.addLayer(lineLayer) } MapView.swift (FP+40/
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36. ࣮ࡍʹඳըؔ਺Λݺͼग़͢ MapView.swift class Coordinator: NSObject, MGLMapViewDelegate { // 省略 func mapViewDidFinishLoadingMap(_ mapView: MGLMapView) { self.control.drawRailwayAndStation(mapView) } } func drawRailwayAndStation(_ mapView: MGLMapView) { Task { let municipalityData = await loadGeoJSONData(resourceName: "TX_Municipality") let railwayData = await loadGeoJSONData(resourceName: "TX_Railway") let stationData = await loadGeoJSONData(resourceName: "TX_Station") await MainActor.run { drawMunicipality(mapView, geoJson: municipalityData) drawRailway(mapView, geoJson: railwayData) drawStation(mapView, geoJson: stationData) } } } ௥ه ௥ه ඳըॱʹ஫ҙ
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38. ͓ΘΓʹ ࠓճͷ(FP+40/දࣔαϯϓϧ͸(JU)VCʹͯެ։͍ͯ͠·͢ IUUQTHJUIVCDPNLLL59.BQ4BNQMF ·ͨɺ͜ͷදࣔαϯϓϧΛجʹͯ͠ޙ೔2JJUBهࣄΛॻ͘༧ఆͰ͢
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