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Read polyline from ArcGIS Route Service compressed geometry.
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| extension AGSGeometry { | |
| static func decodeCompressedGeometry(_ compressedString: String, spatialReference sr: AGSSpatialReference) -> AGSPolyline? { | |
| // Break the string up into signed parts. | |
| // The first part is a coefficient. | |
| // Subsequent pairs of parts make up the remaining coordinates, encoded. | |
| let pattern = #"((\+|\-)[^\+\-]+)"# | |
| guard let regex = try? NSRegularExpression(pattern: pattern, options: []) else { | |
| return nil | |
| } | |
| let compressedParts = regex.matches( | |
| in: compressedString, | |
| range: NSRange(compressedString.startIndex ..< compressedString.endIndex, | |
| in: compressedString) | |
| ).lazy.compactMap { | |
| Range($0.range(at: 0), in: compressedString) | |
| }.compactMap { range -> Double? in | |
| Double(Int(compressedString[range], radix: 32) ?? 0) | |
| } | |
| guard let coefficient = compressedParts.first else { | |
| preconditionFailure("Invalid compressed geometry. Needs coefficient.") | |
| } | |
| guard compressedParts.count >= 5, | |
| (compressedParts.count - 1) % 2 == 0 else { | |
| preconditionFailure("Invalid compressed geometry. Needs even number of subsequent parts, and at least 2 subsequent parts!") | |
| } | |
| struct XYVector { | |
| var x: Double | |
| var y: Double | |
| mutating func applyDelta(_ delta: XYVector) { | |
| x += delta.x | |
| y += delta.y | |
| } | |
| } | |
| let deltas = compressedParts.dropFirst().reduce([[Double]]()) { partialResult, nextVal in | |
| if let lastCoordinate = partialResult.last, | |
| lastCoordinate.count < 2 { | |
| return partialResult.dropLast() + [lastCoordinate + [nextVal]] | |
| } else { | |
| return partialResult + [[nextVal]] | |
| } | |
| }.map( { XYVector(x: $0[0], y: $0[1]) } ) | |
| var cumulativeCoordinate = XYVector(x: 0, y: 0) | |
| let builder = deltas.reduce(AGSPolylineBuilder(spatialReference: sr)) { builder, delta in | |
| // Each coordinate pair is a delta from the last point, so we just keep a cumulative last coordinate. | |
| cumulativeCoordinate.applyDelta(delta) | |
| builder.add(AGSPoint(x: cumulativeCoordinate.x / coefficient, | |
| y: cumulativeCoordinate.y / coefficient, | |
| spatialReference: sr)) | |
| return builder | |
| } | |
| return builder.toGeometry() | |
| } | |
| } | |
| // See https://github.com/Esri/terraformer-arcgis-parser/pull/15/files for algorithm. | |
| // and https://help.arcgis.com/en/sdk/10.0/java_ao_adf/api/arcobjects/com/esri/arcgis/networkanalyst/INACompactStreetDirectionProxy.html#getCompressedGeometry() |
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| // Example | |
| var sampleCompressedGeometry = "+1m91-66os4+1poms+1+91+3+3j" | |
| let line = AGSGeometry.decodeCompressedGeometry(sampleCompressedGeometry, spatialReference: .wgs84()) | |
| print("Got a line: \(line)") | |
| var decodedCoordinates = [ | |
| [ -117.1816137447153, 34.057461545380946 ],[ -117.18159575425025, 34.06266078978142 ], [ -117.18154178285509, 34.06472969326257 ] | |
| ].map { AGSPointMakeWGS84($0[1], $0[0]) } |
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