ios - iOS在drawRect中反转蒙版

Question

使用下面的代码，我成功地掩盖了我的绘图的一部分，但这与我想要掩盖的相反。这掩盖了绘图的内部，我想掩盖外部。有没有一种简单的方法来反转这个面具？

myPath下面是一个UIBezierPath。

CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGMutablePathRef maskPath = CGPathCreateMutable();
CGPathAddPath(maskPath, nil, myPath.CGPath);
[maskLayer setPath:maskPath];
CGPathRelease(maskPath);
self.layer.mask = maskLayer;

Answer 1

在形状图层 ( ) 上使用偶数填充，maskLayer.fillRule = kCAFillRuleEvenOdd;您可以添加一个覆盖整个框架的大矩形，然后添加您要屏蔽的形状。这实际上将反转蒙版。

CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
CGMutablePathRef maskPath = CGPathCreateMutable();
CGPathAddRect(maskPath, NULL, someBigRectangle); // this line is new
CGPathAddPath(maskPath, nil, myPath.CGPath);
[maskLayer setPath:maskPath];
maskLayer.fillRule = kCAFillRuleEvenOdd;         // this line is new
CGPathRelease(maskPath);
self.layer.mask = maskLayer;

Answer 2

对于 Swift 3.0

func mask(viewToMask: UIView, maskRect: CGRect, invert: Bool = false) {
    let maskLayer = CAShapeLayer()
    let path = CGMutablePath()
    if (invert) {
        path.addRect(viewToMask.bounds)
    }
    path.addRect(maskRect)

    maskLayer.path = path
    if (invert) {
        maskLayer.fillRule = kCAFillRuleEvenOdd
    }

    // Set the mask of the view.
    viewToMask.layer.mask = maskLayer;
}

Answer 3

根据接受的答案，这是 Swift 中的另一个混搭。我已经把它变成了一个函数，并把它变成了invert可选的

class func mask(viewToMask: UIView, maskRect: CGRect, invert: Bool = false) {
    let maskLayer = CAShapeLayer()
    let path = CGPathCreateMutable()
    if (invert) {
        CGPathAddRect(path, nil, viewToMask.bounds)
    }
    CGPathAddRect(path, nil, maskRect)

    maskLayer.path = path
    if (invert) {
        maskLayer.fillRule = kCAFillRuleEvenOdd
    }

    // Set the mask of the view.
    viewToMask.layer.mask = maskLayer;
}

Answer 4

这是我的 Swift 4.2 解决方案，它允许圆角半径

extension UIView {

    func mask(withRect maskRect: CGRect, cornerRadius: CGFloat, inverse: Bool = false) {
        let maskLayer = CAShapeLayer()
        let path = CGMutablePath()
        if (inverse) {
            path.addPath(UIBezierPath(roundedRect: self.bounds, cornerRadius: cornerRadius).cgPath)
        }
        path.addPath(UIBezierPath(roundedRect: maskRect, cornerRadius: cornerRadius).cgPath)

        maskLayer.path = path
        if (inverse) {
            maskLayer.fillRule = CAShapeLayerFillRule.evenOdd
        }

        self.layer.mask = maskLayer;
    }

}

Answer 5

斯威夫特 5

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        let red = UIView(frame: view.bounds)
        view.addSubview(red)
        view.backgroundColor = UIColor.cyan
        red.backgroundColor = UIColor.red
        red.mask(CGRect(x: 50, y: 50, width: 50, height: 50), invert: true)
    }
}

extension UIView{

    func mask(_ rect: CGRect, invert: Bool = false) {
        let maskLayer = CAShapeLayer()
        let path = CGMutablePath()
        if (invert) {
            path.addRect(bounds)
        }
        path.addRect(rect)
        maskLayer.path = path
        if (invert) {
            maskLayer.fillRule = CAShapeLayerFillRule.evenOdd
        }
        // Set the mask of the view.
        layer.mask = maskLayer
    }
}

谢谢@arvidurs

Answer 6

对于斯威夫特 4.2

func mask(viewToMask: UIView, maskRect: CGRect, invert: Bool = false) {
    let maskLayer = CAShapeLayer()
    let path = CGMutablePath()
    if (invert) {
        path.addRect(viewToMask.bounds)
    }
    path.addRect(maskRect)

    maskLayer.path = path
    if (invert) {
        maskLayer.fillRule = .evenOdd
    }

    // Set the mask of the view.
    viewToMask.layer.mask = maskLayer;
}

Answer 7

为了反转掩码，您可以像这样

1. 在这里，我有交叉矩形的面具，比如

    let crossPath =  UIBezierPath(rect: cutout.insetBy(dx: 30, dy: -5))
             crossPath.append(UIBezierPath(rect: cutout.insetBy(dx: -5, dy: 30)))
               let crossMask = CAShapeLayer()
               crossMask.path = crossPath.cgPath
               crossMask.backgroundColor = UIColor.clear.cgColor
               crossMask.fillRule = .evenOdd
   

2. 在这里，我在我的交叉矩形周围添加第三个矩形，因此使用 .evenOdd 它占用的面积等于（新矩形 - 旧交叉矩形），换句话说，在交叉矩形的区域之外

     let crossPath = UIBezierPath(rect: cutout.insetBy(dx: -5, dy: -5) )
       crossPath.append(UIBezierPath(rect: cutout.insetBy(dx: 30, dy: -5)))
       crossPath.append(UIBezierPath(rect: cutout.insetBy(dx: -5, dy: 30)))
       let crossMask = CAShapeLayer()
       crossMask.path = crossPath.cgPath
       crossMask.backgroundColor = UIColor.clear.cgColor
       crossMask.fillRule = .evenOdd