对仅更改其他属性的图层属性进行动画处理？ [英] Animate a layer property which simply changes other properties?
问题描述
想象一个 CAGradientLayer 。
为 .startPoint设置动画非常容易和 .endPoint 。
现在想象一个浮动 spinLike 只需同时设置它们两者。
Now imagine a float spinLike which simply sets both of them at once.
{因此，您不必制作两个不同的动画，而只需制作动画 spinLike 。}
{So, instead of having two different animations, you could simply animate spinLike.}
所以类似..
class CustomGradientLayer: CAGradientLayer {
@objc var spinLike: CGFloat = 0 {
didSet {
startPoint = CGPoint( ... )
endPoint = CGPoint( ... )
setNeedsDisplay()
}
}
}
为 spinLike 动画$ b
class Test: UIView {
...
g = CustomGradientLayer()
a = CABasicAnimation(keyPath: "spinLike")
...
g.add(a, forKey: nil)
...
但是。
它不起作用， startPoint 和 endPoint 根本不会移动。
It doesn't work, startPoint and endPoint are not moved at all.
怎么了？
注意-可悲的是，您似乎无法 @ NSManaged 一个具有didSet ...的属性...
Note - tragically it seems you can not @NSManaged a property which has a didSet...
注意-只需覆盖绘制循环，即可轻松制作自己的自定义动画 >。
周围有很多例子。这是您的操作方式：
There are many examples of this around. This is how you do it:
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
通过动画属性 spinLike ，
想要更改每个框架现有的普通动画属性（在示例中， .startPoint 和 .endPoint ）
I simply want to change each frame existing ordinary animatable properties (in the example, .startPoint and .endPoint )
您如何做？
注意！您不能在 drawInContext .startPoint 和 .endPoint >-您将试图修改只读层
Note! You can't change .startPoint and .endPoint in drawInContext - you'd be attempting to modify read-only layer
推荐答案
要制作自定义属性的动画，应使用 @NSManaged 对其进行标记。分配新值时，不应强制重绘。相反，您应该覆盖 needsDisplay（forKey :) 。
To animate custom properties, you should mark them with @NSManaged. You should not force redrawing when you assign a new value. Instead, you should overwrite 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，您应该根据 Apple文档。
我在Swift中写了一个小项目前。它演示了具有Koch曲线深度的自定义图层动画。
I wrote a small project in Swift some months ago. It demonstrates custom layer animations with the depth of a Koch curve.
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)
}
}
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