Question

我有一个CGRect值，需要在它周围画一个边框。我只是希望绘制角落而不用任何连接它们的线条。

像这样......

我如何使用swift绘制此图？

Answer 1

你画出的形状与超人进入紧身衣的方式相同：一次一条腿。将形状分为三个部分：垂直腿，形成圆角的90度弧和水平腿。现在轮流画出每一个。

我将通过展示如何绘制一个角来说明;其他三个角是相似和对称的，留给读者练习。

假设r是我们的矩形，我们处于绘图环境中（例如UIView的draw(_:)或图像视图图形上下文）。让我们做一些初步的假设（随意改变它们）：

UIColor.yellow.setStroke()
let segLength : CGFloat = 40
let cornerSize : CGFloat = 10
let lineWidth : CGFloat = 6

现在我们只需要形成一条贝塞尔曲线路径，描述角落的一条腿，圆角弧和角落的另一条腿，然后抚摸它：

 let p = UIBezierPath()
 p.lineWidth = lineWidth
 // draw top left corner
 p.move(to: CGPoint(x:r.minX, y:r.minY + segLength + cornerSize))
 p.addLine(to: CGPoint(x:r.minX, y:r.minY + cornerSize))
 p.addArc(withCenter: CGPoint(x:r.minX + cornerSize, y:r.minY + cornerSize),
    radius: cornerSize,
    startAngle: CGFloat.pi,
    endAngle: CGFloat.pi * 3.0 / 2.0,
    clockwise: true)
p.addLine(to:CGPoint(x:r.minX + segLength + cornerSize, y:r.minY))
p.stroke()

结果看起来像这样（我用蓝色阴影背景使其更容易看到，而且我已经放大了一点）：

其他三个角的工作方式完全相同，只是改变了需要改变的明显事物。

Answer 2

这是一个自定义UIView类，它使用四个角来绘制自己。您可以设置各种属性以获得所需的外观。

class CornerRect: UIView {
    var color = UIColor.black {
        didSet {
            setNeedsDisplay()
        }
    }
    var radius: CGFloat = 5 {
        didSet {
            setNeedsDisplay()
        }
    }
    var thickness: CGFloat = 2 {
        didSet {
            setNeedsDisplay()
        }
    }
    var length: CGFloat = 30 {
        didSet {
            setNeedsDisplay()
        }
    }

    override func draw(_ rect: CGRect) {
        color.set()

        let t2 = thickness / 2
        let path = UIBezierPath()
        // Top left
        path.move(to: CGPoint(x: t2, y: length + radius + t2))
        path.addLine(to: CGPoint(x: t2, y: radius + t2))
        path.addArc(withCenter: CGPoint(x: radius + t2, y: radius + t2), radius: radius, startAngle: CGFloat.pi, endAngle: CGFloat.pi * 3 / 2, clockwise: true)
        path.addLine(to: CGPoint(x: length + radius + t2, y: t2))

        // Top right
        path.move(to: CGPoint(x: frame.width - t2, y: length + radius + t2))
        path.addLine(to: CGPoint(x: frame.width - t2, y: radius + t2))
        path.addArc(withCenter: CGPoint(x: frame.width - radius - t2, y: radius + t2), radius: radius, startAngle: 0, endAngle: CGFloat.pi * 3 / 2, clockwise: false)
        path.addLine(to: CGPoint(x: frame.width - length - radius - t2, y: t2))

        // Bottom left
        path.move(to: CGPoint(x: t2, y: frame.height - length - radius - t2))
        path.addLine(to: CGPoint(x: t2, y: frame.height - radius - t2))
        path.addArc(withCenter: CGPoint(x: radius + t2, y: frame.height - radius - t2), radius: radius, startAngle: CGFloat.pi, endAngle: CGFloat.pi / 2, clockwise: false)
        path.addLine(to: CGPoint(x: length + radius + t2, y: frame.height - t2))

        // Bottom right
        path.move(to: CGPoint(x: frame.width - t2, y: frame.height - length - radius - t2))
        path.addLine(to: CGPoint(x: frame.width - t2, y: frame.height - radius - t2))
        path.addArc(withCenter: CGPoint(x: frame.width - radius - t2, y: frame.height - radius - t2), radius: radius, startAngle: 0, endAngle: CGFloat.pi / 2, clockwise: true)
        path.addLine(to: CGPoint(x: frame.width - length - radius - t2, y: frame.height - t2))

        path.lineWidth = thickness
        path.stroke()
    }
}

样本用法：

let cr = CornerRect(frame: CGRect(x: 0, y: 0, width: 300, height: 500))
cr.color = .yellow
cr.thickness = 5
cr.backgroundColor = .white

将其复制并粘贴到游乐场。尝试不同的属性值。

Answer 3

由于花了我一段时间才能弄清楚，所以我将使用@matt的答案来分享“需要更改的显而易见的内容”以完成矩形的其余部分：）

let p = UIBezierPath()
p.lineWidth = lineWidth
// draw top left corner
p.move(to: CGPoint(x:r.minX, y:r.minY + segLength + cornerSize))
p.addLine(to: CGPoint(x:r.minX, y:r.minY + cornerSize))
p.addArc(withCenter: CGPoint(x:r.minX + cornerSize, y:r.minY + cornerSize),
            radius: cornerSize, startAngle: CGFloat.pi, endAngle: CGFloat.pi * 1.5, clockwise: true)
p.addLine(to:CGPoint(x:r.minX + segLength + cornerSize, y:r.minY))
// draw top right corner
p.move(to: CGPoint(x:r.maxX - segLength - cornerSize, y:r.minY ))
p.addLine(to: CGPoint(x:r.maxX - cornerSize, y:r.minY ))
p.addArc(withCenter: CGPoint(x:r.maxX - cornerSize, y:r.minY + cornerSize),
            radius: cornerSize, startAngle: CGFloat.pi * 1.5, endAngle: 0, clockwise: true)
p.addLine(to:CGPoint(x:r.maxX, y:r.minY + segLength + cornerSize))
// draw bottom right corner
p.move(to: CGPoint(x:r.maxX, y:r.maxY - segLength - cornerSize))
p.addLine(to: CGPoint(x:r.maxX, y:r.maxY - cornerSize ))
p.addArc(withCenter: CGPoint(x:r.maxX - cornerSize, y:r.maxY - cornerSize),
radius: cornerSize, startAngle: 0, endAngle: CGFloat.pi * 0.5, clockwise: true)
p.addLine(to:CGPoint(x:r.maxX - segLength - cornerSize, y:r.maxY))
// draw bottom left corner
p.move(to: CGPoint(x:r.minX + segLength + cornerSize, y:r.maxY))
p.addLine(to: CGPoint(x:r.minX + cornerSize, y:r.maxY ))
p.addArc(withCenter: CGPoint(x:r.minX + cornerSize, y:r.maxY - cornerSize),
radius: cornerSize, startAngle: CGFloat.pi * 0.5, endAngle: CGFloat.pi, clockwise: true)
p.addLine(to:CGPoint(x:r.minX, y:r.maxY - segLength - cornerSize))
p.stroke()

如何绘制一个矩形的角（没有连接它们的线）

3 个答案: