CABasicAnimation - 变换比例保持居中

Question

尝试动画蒙上UIView的椭圆，将比例变换保留在中心位置。

我发现CALayer - CABasicAnimation not scaling around center/anchorPoint，和随后加入一bounds属性到maskLayerCAShapeLayer然而，这与掩模定位在左上角只有它的1/4表示结束。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]; 
} 

动画...

-(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

我似乎与在position键一秒钟的动画有固定的这个。这是正确的还是有更好的方法来做到这一点？

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

我似乎已经用位置键上的第二个动画来解决这个问题。这是正确的还是有更好的方法来做到这一点？

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

可以围绕对象，而不是中心创建一个规模（0,0）是这样的：

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]; 

所以我们用“身份”开始了变换（意思是“无转变'）。然后我们翻译（移动）到对象的中心。然后我们缩放。然后我们回到原点，所以我们回到了我们开始的地方（我们只想影响比例操作）。

Answer 3

我不知道为什么，但CAShapeLayer不会将边界属性设置为图层。就我而言，这就是问题所在。 尝试设置边界。这应该工作。

我做了这样的事情建立初始圈

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"]; 

而像这样的缩放来

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默认情况下（0.5 ,. 5）根据苹果的文件...但我们都知道这并不意味着什么是正确的？

希望它有帮助！

Answer 4

我已经写了以下功能与许多添加的调整和选项，可能对许多其他人有用。

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：不要忘了更新动画完成后的大小，因为CATransaction恢复到实际大小。