48 lines
1.5 KiB
Swift
48 lines
1.5 KiB
Swift
//
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// CurveAlgorithm.swift
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//
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// Ref: https://github.com/nhatminh12369/LineChart/blob/master/LineChart/CurveAlgorithm.swift
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import UIKit
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struct CurvedSegment {
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var controlPoint1: CGPoint
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var controlPoint2: CGPoint
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}
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class CurveAlgorithm {
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static let shared = CurveAlgorithm()
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private func controlPointsFrom(points: [CGPoint]) -> [CurvedSegment] {
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var result: [CurvedSegment] = []
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let delta: CGFloat = 0.2
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// only use horizontal control point
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for i in 1..<points.count {
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let A = points[i-1]
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let B = points[i]
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let controlPoint1 = CGPoint(x: A.x + delta*(B.x-A.x), y: A.y)
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let controlPoint2 = CGPoint(x: B.x - delta*(B.x-A.x), y: B.y)
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let curvedSegment = CurvedSegment(controlPoint1: controlPoint1, controlPoint2: controlPoint2)
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result.append(curvedSegment)
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}
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return result
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}
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// Create a curved bezier path that connects all points in the dataset
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func createCurvedPath(_ dataPoints: [CGPoint]) -> UIBezierPath? {
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let path = UIBezierPath()
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path.move(to: dataPoints[0])
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var curveSegments: [CurvedSegment] = []
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curveSegments = controlPointsFrom(points: dataPoints)
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for i in 1..<dataPoints.count {
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path.addCurve(to: dataPoints[i], controlPoint1: curveSegments[i-1].controlPoint1, controlPoint2: curveSegments[i-1].controlPoint2)
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}
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return path
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}
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}
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