addArc(withCenter) 闭合路径 [英] addArc(withCenter) closing path

问题描述

以下代码:

  let size = CGSize(width: 200, height: 30)
  let rect = CGRect(origin: .zero, size: size)

  let path1 = UIBezierPath()
  path1.move(to: CGPoint(x: 10, y: 5))
  path1.addLine(to: CGPoint(x: 180, y: 5))
  path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, 
    startAngle: (3.14159 / 2), endAngle: (3 * 3.14159 / 2), clockwise: false)

产生这个:

好的，我是不是遗漏了什么?我不想关闭这条路.我从不调用 path1.close().我想从弧的末端添加另一条直线，而不是从它的封闭版本.基本上，我不想关闭半圆，我该怎么做?

Ok, am I missing something? I do not want to close this path. I never call path1.close(). I want to add another straight line from the end of the arc, not from the closed version of it. Basically, I don't want the half circle to be closed, how can I do that?

推荐答案

您需要在 -90 度处开始圆弧并在 +90 度处结束圆弧.你还需要改变它的方向.您需要执行以下操作:

You need to start your arc at -90 degrees and end it at +90 degrees. You need also to change its direction. You need to do as follow:

path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, startAngle: -.pi/2, endAngle: .pi/2, clockwise: true)

如果你想完成形状，它看起来像这样:

If you would like to complete the shape it would look like this:

let path1 = UIBezierPath()
path1.move(to: CGPoint(x: 10, y: 5))
path1.addLine(to: CGPoint(x: 180, y: 5))
path1.addArc(withCenter: CGPoint(x: 180, y: 20), radius: 15, startAngle: -.pi/2, endAngle: .pi/2, clockwise: true)
path1.addLine(to: CGPoint(x: 10, y: 35))
path1.addArc(withCenter: CGPoint(x: 10, y: 20), radius: 15, startAngle: .pi/2, endAngle:-.pi/2 , clockwise: true)

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