CABasicAnimation - 變換比例保持居中

Question

嘗試動畫蒙上UIView的橢圓，將比例變換保留在中心位置。

我發現CALayer - CABasicAnimation not scaling around center/anchorPoint，和隨後加入一bounds屬性到maskLayerCAShapeLayer然而，這與掩模定位在左上角只有它的1/4表示結束。我希望面具保持在屏幕的中心。

@synthesize maskedView; 
- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    UIViewController *vc = [self.storyboard instantiateViewControllerWithIdentifier:@"Next"]; 

    vc.view.frame = CGRectMake(0,0, self.view.frame.size.width, self.view.frame.size.height); 
vc.view.layer.bounds = self.view.layer.bounds; 

    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init]; 

    CGRect maskRect = CGRectMake((self.view.frame.size.width/2)-50, (self.view.frame.size.height/2)-50, 100, 100); 
    CGMutablePathRef path = CGPathCreateMutable(); 
    CGPathAddEllipseInRect(path, nil, maskRect); 
    [maskLayer setPath:path]; 

    CGPathRelease(path); 

    vc.view.layer.mask = maskLayer; 
    [self.view addSubview:vc.view]; 

    maskedView = vc.view; 
    [self startAnimation]; 
} 

動畫...

-(void)startAnimation 
{ 
    maskedView.layer.mask.bounds = CGRectMake((self.view.frame.size.width/2)-50, (self.view.frame.size.height/2)-50, 100, 100); 
    maskedView.layer.mask.anchorPoint = CGPointMake(.5,.5); 
    maskedView.layer.mask.contentsGravity = @"center"; 

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.scale"]; 

    animation.duration = 1.0f; 
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
    animation.fromValue = [NSNumber numberWithFloat:1.0f]; 
    animation.toValue = [NSNumber numberWithFloat:5.0f]; 

    [maskedView.layer.mask addAnimation:animation forKey:@"animateMask"]; 
} 

---

更新

我似乎與在position鍵一秒鐘的動畫有固定的這個。這是正確的還是有更好的方法來做到這一點？

CABasicAnimation *animation2 = [CABasicAnimation animationWithKeyPath:@"position"]; 

animation2.duration = 1.0f; 

animation2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 

animation2.fromValue = [NSValue valueWithCGPoint:CGPointMake((self.view.frame.size.width/2), (self.view.frame.size.height/2))]; 
animation2.toValue = [NSValue valueWithCGPoint:CGPointMake((self.view.frame.size.width/2), (self.view.frame.size.height/2))]; 

[toBeMask.layer.mask addAnimation:animation2 forKey:@"animateMask2"]; 

Answer 1

我似乎已經用位置鍵上的第二個動畫來解決這個問題。這是正確的還是有更好的方法來做到這一點？

CABasicAnimation *animation2 = [CABasicAnimation animationWithKeyPath:@"position"]; 

animation2.duration = 1.0f; 

animation2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 

animation2.fromValue = [NSValue valueWithCGPoint:CGPointMake((self.view.frame.size.width/2), (self.view.frame.size.height/2))]; 
animation2.toValue = [NSValue valueWithCGPoint:CGPointMake((self.view.frame.size.width/2), (self.view.frame.size.height/2))]; 

[toBeMask.layer.mask addAnimation:animation2 forKey:@"animateMask2"]; 

Answer 2

可以圍繞對象，而不是中心創建一個規模（0,0）是這樣的：

CABasicAnimation *scale = [CABasicAnimation animationWithKeyPath:@"transform"]; 
CATransform3D tr = CATransform3DIdentity; 
tr = CATransform3DTranslate(tr, self.bounds.size.width/2, self.bounds.size.height/2, 0); 
tr = CATransform3DScale(tr, 3, 3, 1); 
tr = CATransform3DTranslate(tr, -self.bounds.size.width/2, -self.bounds.size.height/2, 0); 
scale.toValue = [NSValue valueWithCATransform3D:tr]; 

所以我們用「身份」開始了變換（意思是「無轉變'）。然後我們翻譯（移動）到對象的中心。然後我們縮放。然後我們回到原點，所以我們回到了我們開始的地方（我們只想影響比例操作）。

Answer 3

我不知道爲什麼，但CAShapeLayer不會將邊界屬性設置爲圖層。就我而言，這就是問題所在。 嘗試設置邊界。這應該工作。

我做了這樣的事情建立初始圈

self.circle = [CAShapeLayer layer]; 
CGRect roundedRect = CGRectMake(0, 0, width, width); 
self.circle.bounds = roundedRect; 
UIBezierPath *start = [UIBezierPath bezierPathWithRoundedRect:roundedRect cornerRadius:width/2]; 
[self.circle setPath:start.CGPath]; 
self.circle.position = CGPointMake(whatever suits you); 
self.circleView.layer.mask = self.circle; 
[self.circleView.layer.mask setValue: @(1) forKeyPath: @"transform.scale"]; 

而像這樣的縮放來

CABasicAnimation *scale = [CABasicAnimation animationWithKeyPath:@"transform.scale"]; 
scale.fromValue = [self.circleView.layer.mask valueForKeyPath:@"transform.scale"]; 
scale.toValue = @(100); 
scale.duration = 1.0; 
scale.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
[self.circleView.layer.mask setValue:scale.toValue forKeyPath:scale.keyPath]; 
[self.circleView.layer.mask addAnimation:scale forKey:scale.keyPath]; 

PD：AnchorPoint默認情況下（0.5 ,. 5）根據蘋果的文件...但我們都知道這並不意味着什麼是正確的？

希望它有幫助！

Answer 4

我已經寫了以下功能與許多添加的調整和選項，可能對許多其他人有用。

func layerScaleAnimation(layer: CALayer, duration: CFTimeInterval, fromValue: CGFloat, toValue: CGFloat) { 
    let timing = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn) 
    let scaleAnimation: CABasicAnimation = CABasicAnimation(keyPath: "transform.scale") 

    CATransaction.begin() 
    CATransaction.setAnimationTimingFunction(timing) 
    scaleAnimation.duration = duration 
    scaleAnimation.fromValue = fromValue 
    scaleAnimation.toValue = toValue 
    layer.add(scaleAnimation, forKey: "scale") 
    CATransaction.commit() 
} 

注：不要忘了更新動畫完成後的大小，因爲CATransaction恢復到實際大小。