swift - CABasicAnimation 忽略持续时间

Question

无论我是否使用 CATransation，我似乎都无法控制简单核心动画的持续时间。

事务完成代码在我的持续时间设置后触发，就像我期望的那样，但旋转动画总是需要大约 0.5 秒，无论它设置为什么持续时间。

但是，如果我注释掉设置变换的最后一行，动画就会以适当的速度移动，但随后会恢复到原始旋转。

我错过了什么？

class MyControl: NSControl {
    var shapeLayer = CAShapeLayer()

    required override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        self.wantsLayer = true
        self.layerContentsRedrawPolicy = NSViewLayerContentsRedrawPolicy.OnSetNeedsDisplay

        // create a triangle shape
        let path = NSBezierPath()
        path.moveToPoint(CGPointMake(45.0, 25.0))
        path.lineToPoint(CGPointMake(5.0, 5.0))
        path.lineToPoint(CGPointMake(5.0, 45.0))
        path.lineToPoint(CGPointMake(45.0, 25.0))
        path.closePath()
        shapeLayer.frame = self.bounds
        shapeLayer.path = path.toCGPath()
        shapeLayer.fillColor = NSColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0).CGColor
        self.layer!.addSublayer(shapeLayer)
    }

    override func mouseUp(theEvent: NSEvent){
        let duration = 2.0
        let endAngle = -90.0
        let startAngle = shapeLayer.valueForKey("transform.rotation")

        CATransaction.begin()
        CATransaction.setAnimationDuration(duration)
        CATransaction.setAnimationTimingFunction(CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut))
        CATransaction.setCompletionBlock({
            Swift.print("this fires after 2 seconds")
        })

        let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
        rotateAnimation.removedOnCompletion = true
        rotateAnimation.autoreverses = false
        rotateAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        rotateAnimation.duration = duration
        rotateAnimation.fromValue = startAngle
        rotateAnimation.toValue = endAngle.degreesToRadians
        shapeLayer.addAnimation(rotateAnimation, forKey: rotateAnimation.keyPath)
        CATransaction.commit()

        // mystery line...
        shapeLayer.transform = CATransform3DMakeRotation(endAngle.degreesToRadians, 0.0, 0.0, 1.0)
    }


}

顺便说一句，我使用了几个有用的扩展...NSBezierPath 中的 toCGPath 和 CGFloat 中的 DegreeToRadians。

Answer 1

您看到这种奇怪行为的原因是使用了显式 CATransaction begin--commit。这将依次在运行循环已拥有的 CATransaction 中添加一个嵌套的 CATransaction。所以发生的情况是，您的内部事务被提交，但在关联的动画完成之前，您立即获得了新的转换值。这将导致这个故障，您的图层将快速旋转并消失。

取而代之的是，直接的方法是1. 创建动画2. 为您的动画设置委托(delegate)3. 在委托(delegate)回调中设置您希望图层保留的目标值。

 override func mouseUp(theEvent: NSEvent){
    let duration = 2.0
    let endAngle = -90.0
    let startAngle = shapeLayer.valueForKey("transform.rotation")

    //Set up animation
    let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation")
    rotateAnimation.removedOnCompletion = true
    rotateAnimation.autoreverses = false
    rotateAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
    rotateAnimation.duration = duration
    rotateAnimation.fromValue = startAngle
    rotateAnimation.toValue = endAngle * 3.142/180

    //Setup delegate
    rotateAnimation.delegate = self

    shapeLayer.addAnimation(rotateAnimation, forKey: @"rotationAnimation")

  }


  public override func animationDidStop(anim: CAAnimation, finished flag: Bool){
    shapeLayer.transform  = CATransform3DMakeRotation(CGFloat(-90.0 * 3.142/180), 0.0, 0.0, 1.0)
  }

P.S:我还没有运行此代码，并请注意动画完成后您要为图层的变换设置什么值。