ios - 使用 CABasicAnimation 缩放 CAShapeLayer 会导致它平移
问题描述
我有一个 CAShapeLayer,它被绘制为一个给定的圆圈point
:
let circlePath = UIBezierPath(arcCenter: point, radius: 20.0, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
let shapeLayer = CAShapeLayer()
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.black.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
我希望能够使用 CABasicAnimation 来缩放这一层。我尝试了几种方法,但大多数都给了我同样的问题:圆圈适当缩放,但似乎同时平移/移动。圆圈缩放和平移的速率似乎会影响 的值point
:离point
原点越近,圆圈的动画效果就越慢。我显然在这里遗漏了一些基本的东西,但我一直没能找到它。这是迄今为止我尝试过的构建动画的最简单尝试:
let growthAnimation = CABasicAnimation(keyPath: "transform.scale")
growthAnimation.toValue = 3
growthAnimation.fillMode = .forwards
growthAnimation.isRemovedOnCompletion = false
growthAnimation.duration = 1.0
shapeLayer.add(growthAnimation, forKey: nil)
self.view.layer.addSublayer(shapeLayer)
我尝试设置“transform”(而不是“transform.scale”),我尝试使用 NSValue 作为动画的 toValue,我尝试将转换添加到转换以尝试将其保持在当前位置,但没有运气。
我目前的理论是,该层实际上比圆更大,因此随着整个层的缩放,圆似乎只是在平移。但我无法为图层的边框或背景颜色着色,我不确定如何证明这一点。
解决方案
“我目前的理论是,该层实际上比圆形更大,因此随着整个层的缩放......”
你现在的理论是正确的。
试试这样:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let radius: CGFloat = 20.0
let point = CGPoint(x: radius, y: radius)
let circlePath = UIBezierPath(arcCenter: point, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
let shapeLayer = CAShapeLayer()
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.black.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
let growthAnimation = CABasicAnimation(keyPath: "transform.scale")
growthAnimation.toValue = 3
growthAnimation.fillMode = .forwards
growthAnimation.isRemovedOnCompletion = false
growthAnimation.duration = 1.0
shapeLayer.add(growthAnimation, forKey: nil)
// set the layer frame
shapeLayer.frame = CGRect(x: view.frame.midX - radius, y: view.frame.midY - radius, width: radius * 2.0, height: radius * 2.0)
shapeLayer.backgroundColor = UIColor.green.cgColor
self.view.layer.addSublayer(shapeLayer)
}
编辑- 这可能会让事情更清楚......
如果您运行此示例,它会创建 4 个带有圆圈的形状图层:
- 圆心在
0,0
,没有给定图层框架 - 圆心在
100,100
,没有给定图层框架 0,0
带有图层框架的圆心x: 100, y: 240, w: 40, h: 40
(40是半径* 2)...圆心是框架的左上角- 圆心在
radius,radius
(so, 20,20) 与图层框架x: 100, y: 380, w: 40, h: 40
(40 是半径 * 2)...圆心现在在图层框架中居中
当您点击视图上的任意位置时,所有 4 个图层都将执行相同的缩放动画(减慢到 3 秒以使其更易于观看)。
然后应该清楚路径和图层框架如何影响转换。
class ViewController: UIViewController {
func test1() -> Void {
let radius: CGFloat = 20.0
let shapeLayer = CAShapeLayer()
// no frame set for the shape layer
// point is at top-left corner of shape layer frame
// since we haven't set a frame for the layer, it's top-left corner of the view
let point = CGPoint(x: 0, y: 0)
let circlePath = UIBezierPath(arcCenter: point, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.red.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
self.view.layer.addSublayer(shapeLayer)
shapeLayer.backgroundColor = UIColor.green.cgColor
}
func test2() -> Void {
let radius: CGFloat = 20.0
let shapeLayer = CAShapeLayer()
// no frame set for the shape layer
// set point to 100,100
let point = CGPoint(x: 100, y: 100)
let circlePath = UIBezierPath(arcCenter: point, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.blue.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
self.view.layer.addSublayer(shapeLayer)
shapeLayer.backgroundColor = UIColor.green.cgColor
}
func test3() -> Void {
let radius: CGFloat = 20.0
let shapeLayer = CAShapeLayer()
// set shape layer frame to 40x40 at 100,240
shapeLayer.frame = CGRect(x: 100.0, y: 240.0, width: radius * 2.0, height: radius * 2.0)
// point is at top-left corner of shape layer frame
let point = CGPoint(x: 0, y: 0)
let circlePath = UIBezierPath(arcCenter: point, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.orange.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
self.view.layer.addSublayer(shapeLayer)
shapeLayer.backgroundColor = UIColor.green.cgColor
}
func test4() -> Void {
let radius: CGFloat = 20.0
let shapeLayer = CAShapeLayer()
// set shape layer frame to 40x40 at 100,380
shapeLayer.frame = CGRect(x: 100.0, y: 380.0, width: radius * 2.0, height: radius * 2.0)
// set point to center of layer frame
let point = CGPoint(x: radius, y: radius)
let circlePath = UIBezierPath(arcCenter: point, radius: radius, startAngle: 0, endAngle: CGFloat.pi * 2.0, clockwise: true)
shapeLayer.path = circlePath.cgPath
shapeLayer.strokeColor = UIColor.black.cgColor
shapeLayer.fillColor = nil
shapeLayer.lineWidth = 2.0
self.view.layer.addSublayer(shapeLayer)
shapeLayer.backgroundColor = UIColor.green.cgColor
}
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.setNavigationBarHidden(true, animated: false)
let t = UITapGestureRecognizer(target: self, action: #selector(self.didTap))
view.addGestureRecognizer(t)
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
test1()
test2()
test3()
test4()
}
@objc func didTap() -> Void {
scaleLayers()
}
func scaleLayers() -> Void {
let growthAnimation = CABasicAnimation(keyPath: "transform.scale")
growthAnimation.toValue = 3
growthAnimation.fillMode = .forwards
growthAnimation.isRemovedOnCompletion = false
growthAnimation.duration = 3.0
guard let layers = view.layer.sublayers else {
return
}
layers.forEach { layer in
if let shapeLayer = layer as? CAShapeLayer {
shapeLayer.add(growthAnimation, forKey: nil)
}
}
}
}
推荐阅读
- arrays - C#传入的字符串值长度在给定范围之间?
- python - 沿两个维度的 Torch 布尔索引
- typescript - SequelizeDatabaseError:类型“public.enum_ ...”不存在
- python - Keras 模型中有 2 个输出,但只有一个缺少值?
- c# - azure Webjob TimerTrigger,强制调度
- postgresql - Postgresql & jsonb:哪里不为空
- java - MediaCodec Android 上的 java.nio.BufferOverflowException
- javascript - 旋转 CSS 和 JavaScript 中的每个字母问题?
- error-handling - 在我的应用程序启动时总线可以关闭总线(使用 linux socketCAN)
- linux - pppd 正在绑定随机 TCP/IP 端口