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| import UIKit | |
| extension UIBezierPath { | |
| // reference: https://github.com/erica/iOS-6-Cookbook/blob/master/C01%20Gestures/08%20-%20Smoothed%20Drawing/UIBezierPath-Points.m | |
| var points: [CGPoint] { | |
| var bezierPoints = [CGPoint]() | |
| cgPath.applyWithBlock { (element: UnsafePointer<CGPathElement>) in | |
| if element.pointee.type != .closeSubpath { | |
| bezierPoints.append(element.pointee.points.pointee) | |
| if element.pointee.type != .addLineToPoint && element.pointee.type != .moveToPoint { | |
| bezierPoints.append(element.pointee.points.advanced(by: 1).pointee) | |
| } | |
| } | |
| if element.pointee.type == .addCurveToPoint { | |
| bezierPoints.append(element.pointee.points.advanced(by: 2).pointee) | |
| } | |
| } | |
| return bezierPoints | |
| } | |
| func smoothened(granularity: Int = 24) { | |
| smoothen(granularity: granularity, into: self) | |
| } | |
| // reference: https://github.com/erica/iOS-6-Cookbook/blob/master/C01%20Gestures/08%20-%20Smoothed%20Drawing/UIBezierPath-Smoothing.m | |
| @discardableResult | |
| func smoothen(granularity: Int = 24, into bezier: UIBezierPath? = nil) -> UIBezierPath { | |
| var allPoints = points | |
| guard allPoints.count > 4 else { | |
| return self | |
| } | |
| allPoints.insert(allPoints.first!, at: 0) | |
| allPoints.append(allPoints.last!) | |
| let smoothened = bezier ?? (copy() as! UIBezierPath) | |
| smoothened.removeAllPoints() | |
| var hasMovedToInitialPoint = false | |
| for i in (4 ..< allPoints.count) { | |
| let subpoints = allPoints[i - 3 ... i] | |
| for i in (1 ..< granularity) { | |
| let t = CGFloat(i) * (CGFloat(1.0) / CGFloat(granularity)) | |
| let tt = t * t | |
| let ttt = tt * t | |
| func smoothenedCoodinateComponeny(fromNearby points: ArraySlice<CGFloat>) -> CGFloat { | |
| // explicit types needed to compile in reasonble time | |
| return CGFloat(0.5) * | |
| ({ CGFloat(2) * points[1] + (points[2] - points[0]) * t }() + | |
| { (CGFloat(2) * points[0] - CGFloat(5) * points[1] + CGFloat(4) * points[2] - points[3]) * tt }() + | |
| { (CGFloat(3) * points[1] - points[0] - CGFloat(3) * points[2] + points[3]) * ttt }()) | |
| } | |
| let pX = smoothenedCoodinateComponeny(fromNearby: subpoints[keyPath: \CGPoint.x]) | |
| let pY = smoothenedCoodinateComponeny(fromNearby: subpoints[keyPath: \CGPoint.y]) | |
| if !hasMovedToInitialPoint { | |
| hasMovedToInitialPoint = true | |
| smoothened.move(to: CGPoint(x: pX, y: pY)) | |
| } else { | |
| smoothened.addLine(to: CGPoint(x: pX, y: pY)) | |
| } | |
| } | |
| smoothened.addLine(to: p2) | |
| } | |
| smoothened.addLine(to: allPoints.last!) | |
| return smoothened | |
| } | |
| } |
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