我想实现一个动画,从一个圆形到一个带有圆角的正方形。据我所知,为了实现平滑动画,两个路径中点的数量应该是相等的。因此,我编写了一个函数,基于弧的数量来构建一个圆形:
private func circleShape(segmentNumber: Int = 8, radius: CGFloat = 32) -> CGPath {
let center = self.bounds.center
let circlePath = UIBezierPath()
let segmentAngle = CGFloat.pi * CGFloat(2) / CGFloat(segmentNumber)
var currentAngle: CGFloat = 0
for _ in 0 ..< segmentNumber {
let nextAngle = currentAngle + segmentAngle
circlePath.addArc(withCenter: center, radius: radius,
startAngle: currentAngle, endAngle: nextAngle, clockwise: true)
currentAngle = nextAngle
}
circlePath.close()
return circlePath.cgPath
}
我正在使用getPathElementsPointsAndTypes()函数检查点的数量,但它与部分数量(segmentNumber)不成比例地增加(segmentNumber: 1, points: 13; sN: 2, p: 14; sN: 3, p: 21; sN: 4, p: 16)。因此,我无法找到与绘制正方形的函数相同点数(19)的segmentNumber
:
private func squareShape(size: CGFloat = 44, radius: CGFloat = 8) -> CGPath {
let rect = CGRect(center: self.bounds.center, size: CGSize(width: size, height: size))
let left = CGFloat.pi
let up = CGFloat(1.5) * CGFloat.pi
let down = CGFloat.pi / CGFloat(2)
let right = CGFloat(0.0)
let squarePath = UIBezierPath()
squarePath.addArc(withCenter: CGPoint(x: rect.minX + radius, y: rect.minY + radius), radius: radius, startAngle: left, endAngle: up, clockwise: true)
squarePath.addArc(withCenter: CGPoint(x: rect.maxX - radius, y: rect.minY + radius), radius: radius, startAngle: up, endAngle: right, clockwise: true)
squarePath.addArc(withCenter: CGPoint(x: rect.maxX - radius, y: rect.maxY - radius), radius: radius, startAngle: right, endAngle: down, clockwise: true)
squarePath.addArc(withCenter: CGPoint(x: rect.minX + radius, y: rect.maxY - radius), radius: radius, startAngle: down, endAngle: left, clockwise: true)
squarePath.close()
return squarePath.cgPath
}
动画代码:
let animation = CABasicAnimation(keyPath: "path")
animation.duration = 2
animation.toValue = self.circleShape()
animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.linear)
self.testLayer.add(animation, forKey: "pathAnimation")
结果:
我应该修改什么才能使这个动画与示例中的一样流畅,但不使用圆角矩形呢?