如何围绕自定义蒙版创建笔划？

Question

我正在尝试使用UIimage在蒙版周围创建边框。当我在代码中创建掩码时，它看起来很好：

@IBOutlet weak var imageToBeMasked: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()
    let mask = UIImageView(image: Image)
    imageToBeMasked.mask = mask
}

但是当我尝试创造一个笔划时，似乎根本不使用面具：

  @IBOutlet weak var imageToBeMasked: UIImageView!

  override func viewDidLoad() {
    super.viewDidLoad()

    let mask = UIImageView(image: Image)

    // the layer used to mask the image view
    let maskLayer = CAShapeLayer()
    maskLayer.path = UIBezierPath(rect: mask.bounds).cgPath
    imageToBeMasked.layer.mask = maskLayer

    // the layer used to draw the border
    let strokeLayer = CAShapeLayer()
    strokeLayer.frame = imageToBeMasked.bounds
    strokeLayer.fillColor = UIColor.clear.cgColor
    strokeLayer.path = UIBezierPath(rect: mask.bounds).cgPath
    strokeLayer.strokeColor = UIColor.black.cgColor
    strokeLayer.lineWidth = 4
    imageToBeMasked.layer.addSublayer(strokeLayer)
}

有关如何解决此问题的任何线索？

Answer 1

CALayer不受遮罩本身的影响。最快的方法是创建一个略大于原始图像的新图像，将其放在原始图像后面并用颜色着色。

let templateImage = originalImage.withRenderingMode(.alwaysTemplate)
strokeImageView.image = templateImage
strokeImageView.tintColor = .black