CAShaperLayer 作为蒙版仅显示 UIView 的 1/4

Question

我尝试让 UIView 显示锯齿形底部边缘。类似于 http://www.shutterstock.com/pic-373176370/stock-vector-receipt-vector-icon-invoice-flat-illustration-cheque-shadow-bill-with-total-cost-amount-and-dollar-symbol-abstract-text-receipt-paper-isolated-on-green.html?src=zMGBKj_5etMCcRB3cKmCoA-1-2

我有创建路径并设置为遮罩的方法，但它显示为视图的 1/4。我需要设置其他东西吗？看起来像视网膜问题或坐标问题，但不确定是哪个。

func layoutZigZag(bounds: CGRect) -> CALayer {
    let maskLayer = CAShapeLayer()
    maskLayer.bounds = bounds
    let path = UIBezierPath()

    let width = bounds.size.width
    let height = bounds.size.height

    let topRight = CGPoint(x: width , y: height)
    let topLeft = CGPoint(x: 0 , y: height)
    let bottomRight = CGPoint(x: width , y: 0)
    let bottomLeft = CGPoint(x: 0 , y: 0)

    let zigzagHeight: CGFloat = 10
    let numberOfZigZag = Int(floor(width / 23.0))
    let zigzagWidth = width / CGFloat(numberOfZigZag)

    path.move(to: topLeft)
    path.addLine(to: bottomLeft)

    // zigzag
    var currentX = bottomLeft.x
    var currentY = bottomLeft.y
    for i in 0..<numberOfZigZag {
        let upper = CGPoint(x: currentX + zigzagWidth / 2, y: currentY + zigzagHeight)
        let lower = CGPoint(x: currentX + zigzagWidth, y: currentY)

        path.addLine(to: upper)
        path.addLine(to: lower)

        currentX += zigzagWidth
    }

    path.addLine(to: topRight)
    path.close()

    maskLayer.path = path.cgPath
    return maskLayer
}

and 

let rect = CGRect(x: 0, y: 0, width: 320, height: 400)
let view = UIView(frame: rect)
view.backgroundColor = UIColor.red
let zigzag = layoutZigZag(bounds: rect)
view.layer.mask = zigzag

路径正确

结果是视图的 1/4

Answer 1

将maskLayer.bounds = bounds更改为maskLayer.frame = bounds

更新：

颠倒是因为 UI 和 CG 之间的差异，我们在 UIBezierPath 中创建路径并将该路径转换为 CGPath (maskLayer.path = path.cgPath)。首先我们要知道区别，CGPath is Quartz 2D and origin is at the bottom left while in UIBezierPath is UIKit 原点在左上角。根据您的代码，应用的坐标是按照左上角的，即 UIBezierPath 当我们转换为 CGPath（原点在左下角）时，它会颠倒过来。所以更改代码如下以获得所需的效果。

    let topRight = CGPoint(x: width , y: 0)
    let topLeft = CGPoint(x: 0 , y: 0)
    let bottomLeft = CGPoint(x: 0 , y: (height - zigzagHeight))

石英二维坐标系

UIBezierPath 坐标系

CAShaperLayer 作为蒙版仅显示 UIView 的 1/4

CAShaperLayer as mask show only 1/4 of UIView

mask

cashapelayer

ios

swift