swift - 如何在 Swift Playground 中调用 UIBezier 大纲？

Question

编辑:抱歉，我最初并不清楚。我想获得线条或形状的“轮廓”路径。我特别想了解如何使用:

context.replacePathWithStrokedPath()

和/或:

CGPathRef CGPathCreateCopyByStrokingPath(CGPathRef path, const CGAffineTransform *transform, CGFloat lineWidth, CGLineCap lineCap, CGLineJoin lineJoin, CGFloat miterLimit);

https://developer.apple.com/documentation/coregraphics/1411128-cgpathcreatecopybystrokingpath?language=objc

我不是在寻找解决方法，谢谢。

=====

我真的想全神贯注地画一条有轮廓的线。我正在使用 UIBezier，但遇到了砖墙。到目前为止，我得到了这个:

import UIKit
import PlaygroundSupport

let screenWidth = 375.0 // points
let screenHeight = 467.0 // points

let centerX = screenWidth / 2.0
let centerY = screenHeight / 2.0

let screenCenterCoordinate = CGPoint(x: centerX, y: centerY)

class LineDrawingView: UIView {
override func draw(_ rect: CGRect) {
    let path = UIBezierPath()
    path.lineWidth = 5
    path.lineCapStyle = .round

    //Move to Drawing Point
    path.move(to: CGPoint(x:20, y:120))
    path.addLine(to: CGPoint(x:200, y:120))

    path.stroke()

    let dot = UIBezierPath()
    dot.lineWidth = 1
    dot.lineCapStyle = .round

    dot.move(to: CGPoint(x:200, y:120))
    dot.addArc(withCenter: CGPoint(x:200, y:120), radius: 5, startAngle: CGFloat(0.0), endAngle: CGFloat(8.0), clockwise: true)

    UIColor.orange.setStroke()
    UIColor.orange.setFill()
    path.stroke()
    dot.fill()

    let myStrokedPath = UIBezierPath.copy(path)

    myStrokedPath().stroke()

  }

}


let tView = LineDrawingView(frame: CGRect(x: 0,y: 0, width: screenWidth, height: screenHeight))
tView.backgroundColor = UIColor.white

PlaygroundPage.current.liveView = tView

那么，我哪里出错了？我似乎无法弄清楚在哪里使用 CGPathCreateCopyByStrokingPath...或者如何...

编辑 2:

好的，现在我明白了。更近了，但我如何再次填充路径？

    let c = UIGraphicsGetCurrentContext()!

    c.setLineWidth(15.0)

    let clipPath = UIBezierPath(arcCenter: CGPoint(x:centerX,y:centerY), radius: 90.0, startAngle: -0.5 * .pi, endAngle: 1.0 * .pi, clockwise: true).cgPath

    c.addPath(clipPath)
    c.saveGState()
    c.replacePathWithStrokedPath()

    c.setLineWidth(0.2)
    c.setStrokeColor(UIColor.black.cgColor)
    c.strokePath()

Answer 1

类稍作修改以生成此图形:

修改后的代码中没有复制路径。相反，现有的路径被用来绘制，然后修改并重新使用。该点没有笔画，因此添加了它。由于只能填充封闭的路径，因此我通过更改线宽在较粗的路径之上绘制了较细的路径。

这是修改后的代码:

class LineDrawingView: UIView {
  override func draw(_ rect: CGRect) {
    let path = UIBezierPath()
    path.lineWidth = 7
    path.lineCapStyle = .round

    //Move to Drawing Point
    path.move(to: CGPoint(x:20, y:120))
    path.addLine(to: CGPoint(x:200, y:120))

    path.stroke()

    let dot = UIBezierPath()
    dot.lineWidth = 1
    dot.lineCapStyle = .round

    dot.move(to: CGPoint(x:200, y:120))
    dot.addArc(withCenter: CGPoint(x:200, y:120), radius: 5, startAngle: CGFloat(0.0), endAngle: CGFloat(8.0), clockwise: true)

    dot.stroke()

    UIColor.orange.setStroke()
    UIColor.orange.setFill()
    path.lineWidth = 5
    path.stroke()
    dot.fill()

  }

}