想象一个 CAGradientLayer
。
.startPoint
和 .endPoint
的动画非常容易。
现在想象一个 float spinLike
,它只是同时设置它们。
{因此,您可以简单地为 spinLike
设置动画,而不是使用两个不同的动画。
所以像..
class CustomGradientLayer: CAGradientLayer {
@objc var spinLike: CGFloat = 0 {
didSet {
startPoint = CGPoint( ... )
endPoint = CGPoint( ... )
setNeedsDisplay()
}
}
}
动画spinLike
...
class Test: UIView {
...
g = CustomGradientLayer()
a = CABasicAnimation(keyPath: "spinLike")
...
g.add(a, forKey: nil)
...
但是。
不行,startPoint
和endPoint
根本就没动
怎么了?
注意 - 不幸的是你似乎不能 @NSManaged
一个有 didSet 的属性...
请注意 - 只需重写绘制循环即可轻松制作您自己的自定义动画。
这方面的例子很多。这是你如何做的:
class CircleProgressLayer: CALayer {
@NSManaged var progress: CGFloat
override class func needsDisplayForKey(key: String) -> Bool {
if key == "progress" {
return true
}
return super.needsDisplayForKey(key)
}
override func draw(in ctx: CGContext) {
path.fill() etc etc... your usual drawing code
}
}
不幸的是我的问题是
与实际绘图无关:
通过动画属性spinLike
,
我只想更改每个帧现有的普通动画属性(在示例中,.startPoint
和 .endPoint
)
你是怎么做到的?
注意!您不能在 drawInContext
中更改 .startPoint
和 .endPoint
- 您将尝试修改只读层
最佳答案
要使自定义属性具有动画效果,您应该使用 @NSManaged
标记它们。分配新值时不应强制重绘。相反,您应该覆盖 needsDisplay(forKey:) .
class CustomedGradLayer: CAGradientLayer {
@NSManaged var spinLike: CGFloat
class func needsDisplay(forKey key: String) -> Bool {
return key == "spinLike" || super.needsDisplay(forKey: key)
}
class func defaultValue(forKey key: String) -> Any? {
return key == "spinLike" ? CGFloat(0) : super.defaultValue(forKey: key)
}
}
最后要根据Apple documentation实现图层的绘制。 .
几个月前我用 Swift 写了一个小项目。它演示了具有科赫曲线深度的自定义层动画。
这是图层类的代码:
class KochLayer: CALayer {
fileprivate let kPI = CGFloat(Double.pi)
@NSManaged var depth : CGFloat
var midPoint: CGPoint {
get {
let theBounds = self.bounds
return CGPoint(x: theBounds.midX, y: theBounds.midY)
}
}
var color: CGColor!
override class func defaultValue(forKey inKey: String) -> Any? {
return inKey == kDepthKey ? 0.0 : super.defaultValue(forKey: inKey)
}
override class func needsDisplay(forKey inKey: String) -> Bool {
if inKey == kDepthKey {
return true
}
else {
return super.needsDisplay(forKey: inKey)
}
}
override init() {
super.init()
}
override init(layer inLayer: Any) {
super.init(layer: inLayer)
if let theLayer = inLayer as? KochLayer {
depth = theLayer.depth
color = theLayer.color
}
}
required init(coder inCoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func pointWithRadius(_ inRadius: CGFloat, angle inAngle: CGFloat) -> CGPoint {
let theCenter = midPoint
return CGPoint(x: theCenter.x + inRadius * sin(inAngle),
y: theCenter.y - inRadius * cos(inAngle));
}
override func draw(in inContext: CGContext) {
let theBounds = self.bounds
let theRadius = fmin(theBounds.width, theBounds.height) / 2.0
let thePoints: [CGPoint] = [
pointWithRadius(theRadius, angle:0.0),
pointWithRadius(theRadius, angle:2 * kPI / 3.0),
pointWithRadius(theRadius, angle:4 * kPI / 3.0)
]
let thePath = CGMutablePath()
inContext.setLineWidth(0.5)
inContext.setLineCap(.round)
inContext.setLineJoin(.round)
inContext.setFillColor(color)
thePath.move(to: thePoints[0])
for i in 0..<3 {
addPointsToPath(thePath, fromPoint:thePoints[i], toPoint:thePoints[(i + 1) % 3], withDepth:self.depth)
}
inContext.addPath(thePath)
inContext.fillPath()
}
func addPointsToPath(_ inoutPath: CGMutablePath, fromPoint inFromPoint: CGPoint, toPoint inToPoint: CGPoint, withDepth inDepth: CGFloat) {
var thePoints = Array<CGPoint>(repeating: inFromPoint, count: 5)
thePoints[4] = inToPoint;
if inDepth <= 1.0 {
curveWithWeight(inDepth, points:&thePoints)
for i in 1..<5 {
inoutPath.addLine(to: thePoints[i])
}
}
else {
let theDepth = inDepth - 1;
curveWithWeight(1.0, points:&thePoints)
for i in 0..<4 {
addPointsToPath(inoutPath, fromPoint:thePoints[i], toPoint:thePoints[i + 1], withDepth:theDepth)
}
}
}
func curveWithWeight(_ inWeight: CGFloat, points inoutPoints: inout [CGPoint]) {
let theFromPoint = inoutPoints[0]
let theToPoint = inoutPoints[4]
let theFactor = inWeight / (2 * sqrt(3))
let theDelta = CGSize(width: theToPoint.x - theFromPoint.x, height: theToPoint.y - theFromPoint.y);
inoutPoints[1] = CGPoint(x: theFromPoint.x + theDelta.width / 3,
y: theFromPoint.y + theDelta.height / 3)
inoutPoints[2] = CGPoint(x: theFromPoint.x + theDelta.width / 2 + theFactor * theDelta.height,
y: theFromPoint.y + theDelta.height / 2 - theFactor * theDelta.width);
inoutPoints[3] = CGPoint(x: theToPoint.x - theDelta.width / 3,
y: theToPoint.y - theDelta.height / 3)
}
}
关于ios - 动画层属性,它只是改变其他属性?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47164762/