使用 CAShapeLayer 动画部分蒙版的透明度

Question

我对.brownbackgroundColor有看法。

在那个视图中我有一个 backgroundView，它有 backgroundColor: UIColor.black.withAlphaComponent(0.5)。

然后我想在这个 backgroundView 中有一个透明框来显示底层视图。我已经实现了这一点，但是我不能通过动画化它的透明度来做到这一点，我的代码只增加 "cut out area" 直到所需的大小而不是动画化它的透明度。

带有 backgroundView 的棕色视图，它是 0.5 alpha

添加图层到 backgroundView 显示部分棕色视图

我编写的代码是这样的：

func addIndicatorTo(global frame: CGRect) {
    let shape = CAShapeLayer()
    let targetRect = convert(frame, from: nil).insetBy(dx: -4, dy: -4)
    let animation = CABasicAnimation(keyPath: "path")

    let toPath = CGMutablePath()
    toPath.addRect(bounds)
    toPath.addPath(UIBezierPath(roundedRect: targetRect,
                                byRoundingCorners: .allCorners,
                                cornerRadii: CGSize(width: 4, height: 4)).cgPath)
    toPath.closeSubpath()

    let fromPath = CGMutablePath()
    fromPath.addRect(bounds)
    fromPath.addPath(UIBezierPath(roundedRect: targetRect.insetBy(dx: targetRect.width / 2,
                                                                  dy: targetRect.height / 2),
                                  byRoundingCorners: .allCorners,
                                  cornerRadii: CGSize(width: 4, height: 4)).cgPath)
    fromPath.closeSubpath()

    animation.fromValue = fromPath
    animation.toValue = toPath
    animation.duration = 0.5

    shape.fillRule = .evenOdd
    shape.path = animation.fromValue as! CGPath

    backgroundView.layer.mask = shape
    shape.add(animation, forKey: nil)

    CATransaction.begin()
    CATransaction.setDisableActions(true)
    shape.path = toPath
    CATransaction.commit()
}

Answer 1

不确定这是否是 "good" 解决方案。但我会坚持下去，直到有人告诉我如何更优雅地解决它！

基本上，我只是创建了一个蒙版并切掉了方框，然后我创建了一个新的 boxLayer，在 "cutout" 的区域绘制。然后我只是为 boxLayer 的 opacity 设置动画。

func addIndicatorTo(global frame: CGRect) {
    let maskLayer = CAShapeLayer()
    let boxLayer = CAShapeLayer()

    let targetRect = convert(frame, from: nil).insetBy(dx: -4, dy: -4)
    let animation = CABasicAnimation(keyPath: "opacity")

    let toPath = CGMutablePath()

    let boxPath = UIBezierPath(roundedRect: targetRect,
                               byRoundingCorners: .allCorners,
                               cornerRadii: CGSize(width: 4, height: 4)).cgPath
    toPath.addRect(bounds)
    toPath.addPath(boxPath)
    toPath.closeSubpath()

    boxLayer.fillColor = UIColor.black.withAlphaComponent(0.5).cgColor
    boxLayer.path = boxPath

    animation.fromValue = 1.0
    animation.toValue = 0.0
    animation.duration = 0.5

    maskLayer.fillRule = .evenOdd
    maskLayer.path = toPath

    backgroundView.layer.mask = maskLayer
    layer.addSublayer(boxLayer)
    boxLayer.add(animation, forKey: nil)

    CATransaction.begin()
    CATransaction.setDisableActions(true)
    boxLayer.opacity = 0.0
    CATransaction.commit()
}

使用 CAShapeLayer 动画部分蒙版的透明度

Animate transparency of part of mask with CAShapeLayer

core-animation

calayer

cashapelayer

ios

swift