Raywenderlich上的CALayers视频例子
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参考CALayers
Raywenderlich上的CALayers视频例子
CAShapeLayer
该例子使用了CAShapeLayer
制作了一个指示器,改变时有动画
该例子的效果如下:
主要实现方式是:
1.一个背景layer,一个前置的layer
2.CABasicAnimation动画,改变strokeEnd
代码如下StatView
:
import UIKit@IBDesignableclass StatView: UIView { let percentLabel = UILabel() let captionLabel = UILabel() var range: CGFloat = 10 var curValue: CGFloat = 0 { didSet { animate() } } let margin: CGFloat = 10 //背景layer let bgLayer = CAShapeLayer() @IBInspectable var bgColor: UIColor = UIColor.grayColor() { didSet { configure() } } //前面的layer let fgLayer = CAShapeLayer() @IBInspectable var fgColor: UIColor = UIColor.blackColor() { didSet { configure() } } override func awakeFromNib() { super.awakeFromNib() setup() configure() } //Called when a designable object is created in Interface Builder. override func prepareForInterfaceBuilder() { super.prepareForInterfaceBuilder() setup() configure() } func setup() { // Setup background layer bgLayer.lineWidth = 20.0 bgLayer.fillColor = nil bgLayer.strokeEnd = 1 layer.addSublayer(bgLayer) //设置fgLayer fgLayer.lineWidth = 20.0 fgLayer.fillColor = nil fgLayer.strokeEnd = 0 layer.addSublayer(fgLayer) // Setup percent label percentLabel.font = UIFont.systemFontOfSize(26) percentLabel.textColor = UIColor.whiteColor() percentLabel.text = "0/0" percentLabel.translatesAutoresizingMaskIntoConstraints = false addSubview(percentLabel) // Setup caption label captionLabel.font = UIFont.systemFontOfSize(26) captionLabel.text = "Chapters Read" captionLabel.textColor = UIColor.whiteColor() captionLabel.translatesAutoresizingMaskIntoConstraints = false addSubview(captionLabel) // Setup constraints let percentLabelCenterX = percentLabel.centerXAnchor.constraintEqualToAnchor(self.centerXAnchor) let percentLabelCenterY = percentLabel.centerYAnchor.constraintEqualToAnchor(self.centerYAnchor, constant: -margin) NSLayoutConstraint.activateConstraints([percentLabelCenterX, percentLabelCenterY]) let captionLabelCenterX = captionLabel.centerXAnchor.constraintEqualToAnchor(self.centerXAnchor, constant: -margin) let captionLabelBottom = captionLabel.bottomAnchor.constraintEqualToAnchor(self.bottomAnchor, constant: -margin) NSLayoutConstraint.activateConstraints([captionLabelCenterX, captionLabelBottom]) } func configure() { bgLayer.strokeColor = bgColor.CGColor fgLayer.strokeColor = fgColor.CGColor } //重写layoutSubviews override func layoutSubviews() { super.layoutSubviews() setupShapeLayer(bgLayer) setupShapeLayer(fgLayer) } //设置path private func setupShapeLayer(shapeLayer:CAShapeLayer) { shapeLayer.frame = self.bounds let startAngle = DegreesToRadians(135.0) let endAngle = DegreesToRadians(45.0) let center = percentLabel.center let radius = CGRectGetWidth(self.bounds) * 0.35 let path = UIBezierPath(arcCenter: center, radius: radius, startAngle: startAngle, endAngle: endAngle, clockwise: true) shapeLayer.path = path.CGPath } private func animate() { percentLabel.text = String(format: "%.0f/%.0f", curValue, range) var fromValue = fgLayer.strokeEnd let toValue = curValue / range if let presentationLayer = fgLayer.presentationLayer() as? CAShapeLayer { fromValue = presentationLayer.strokeEnd } let percentChange = abs(fromValue - toValue) // 创建CABasicAnimation动画 let animation = CABasicAnimation(keyPath: "strokeEnd") animation.fromValue = fromValue animation.toValue = toValue // 动画时间 animation.duration = CFTimeInterval(percentChange * 4) // 移除stroke动画,再添加 fgLayer.removeAnimationForKey("stroke") fgLayer.addAnimation(animation, forKey: "stroke") CATransaction.begin() CATransaction.setDisableActions(true) fgLayer.strokeEnd = toValue CATransaction.commit() }}
说明:
在一个layer上运行动画时,animation其实是在一个叫做presentation layer上发生的,可以把它认为是layer的复制,仅用于animation。
动画改变的属性是位于presentation layer上的,当动画完成后,presentation layer就会被消失,然后就只看见了原来的layer。所以animation并不会自动更新original layer上的属性,需要添加上:
fgLayer.strokeEnd = toValue
还要注意的是改变layer的属性(例如strokeEnd
)会自动触发一个隐式动画(implicit animation)。由于已经运行了自己动画,所以要disable这个隐式动画,以免冲突:
CATransaction.begin()CATransaction.setDisableActions(true)fgLayer.strokeEnd = toValueCATransaction.commit()
还要注意的是,fromValue
要取presentationLayer的值:
if let presentationLayer = fgLayer.presentationLayer() as? CAShapeLayer{ fromValue = presentationLayer.strokeEnd}
Layer Mask
Layers have a mask
property
- Fully or partially opaque pixels: shows content
- Transparent pixels: hides content
可以对view设置mask,显示圆形图像:
let maskLayer = CAShapeLayer()maskLayer.path = UIBezierPath(ovalInRect: layerAvatar.bounds).CGPathlayerAvatar.mask = maskLayerlayerAvatar.path = maskLayer.path
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