鉴于如左图所示的CALayers的排列(背景,框架和文本层),我希望将它们中的两个旋转45°(layer.transform = CATransform3DMakeRotation(.pi / 4, 0, 0, 1)
),导致右边的钻石,但我看到的是中间的对角线。
该元素包括父CALayer,背景图层,边框框架图层和文本图层。我希望能够将元素作为一个整体进行缩放和旋转,因此不可见的父图层和两个预先旋转的子元素:
class ScoreLayer: CALayer {
var score = 0 {
didSet {
updateValue()
}
}
let bgLayer: CALayer = {
let layer = CALayer()
layer.contentsScale = UIScreen.main.scale
layer.backgroundColor = #colorLiteral(red: 0.2392156869, green: 0.6745098233, blue: 0.9686274529, alpha: 1)
layer.shadowOffset = .zero
layer.shadowRadius = 3
layer.shadowColor = UIColor.black.cgColor
layer.shadowOpacity = 0.4
return layer
}()
let textLayer: CATextLayer = {
let layer = CATextLayer()
layer.contentsScale = UIScreen.main.scale
layer.alignmentMode = .center
layer.foregroundColor = UIColor.white.cgColor
layer.fontSize = 20
layer.font = UIFont.preferredFont(forTextStyle: .largeTitle)
return layer
}()
let frameLayer: CALayer = {
let layer = CALayer()
layer.contentsScale = UIScreen.main.scale
layer.borderColor = #colorLiteral(red: 0.2392156869, green: 0.6745098233, blue: 0.9686274529, alpha: 1)
layer.borderWidth = 3
layer.shadowOffset = .zero
layer.shadowRadius = 3
layer.shadowColor = UIColor.black.cgColor
layer.shadowOpacity = 0.7
return layer
}()
override init() {
super.init()
contentsScale = UIScreen.main.scale
addSublayer(bgLayer)
addSublayer(textLayer)
addSublayer(frameLayer)
updateValue()
}
override func layoutSublayers() {
bgLayer.frame = bounds
frameLayer.frame = bounds
textLayer.frame = bounds
bgLayer.transform = CATransform3DMakeRotation(.pi / 4, 0, 0, 1)
frameLayer.transform = CATransform3DMakeRotation(.pi / 4, 0, 0, 1)
}
private func updateValue() {
textLayer.string = "\(score)"
}
}
动画旋转(通过CADisplayLink
设置新变换),看起来旋转层也围绕自己的x轴旋转。我没有在代码清单中设置任何转换而不是两个。
是什么造成的?
应用变换后不要更新帧。 layoutSublayers
被多次调用,复合效果会导致不必要的失真。在应用变换之前在其他地方设置一次帧,或者,如果需要帧更新(可能是为了响应方向更改),请确保删除变换更新帧然后重新应用变换。
编辑添加:
docs实际上明确地说“如果transform属性应用的旋转变换不是90度的倍数,则不设置帧”。