CoreAnimation之CALayer基礎(chǔ)
CoreAnimation之變換
CoreAnimation之常用圖層
修改非RootLayer的一些屬性(支持隱式動(dòng)畫的屬性)會(huì)產(chǎn)生隱式動(dòng)畫
隱式動(dòng)畫的持續(xù)時(shí)間取決于當(dāng)前事務(wù)，隱式動(dòng)畫的類型取決于圖層行為
事務(wù)：
事務(wù)實(shí)際上是Core Animation用來包含一系列屬性動(dòng)畫集合的機(jī)制，任何用指定事務(wù)去改變可以做動(dòng)畫的圖層屬性都不會(huì)立刻發(fā)生變化，而是當(dāng)事務(wù)一旦提交的時(shí)候開始用一個(gè)動(dòng)畫過渡到新值
所謂事務(wù)，具體到代碼中就是CATransaction類，CATransaction沒有屬性或者實(shí)例方法，并且也不能用+alloc和-init方法創(chuàng)建它，常用方法有這些：
/* Begin a new transaction for the current thread; nests. */
+ (void)begin;
/* Commit all changes made during the current transaction. Raises an
* exception if no current transaction exists. */
+ (void)commit;
/* Commits any extant implicit transaction. Will delay the actual commit
* until any nested explicit transactions have completed. */
+ (void)flush;
/* Methods to lock and unlock the global lock. Layer methods automatically
* obtain this while modifying shared state, but callers may need to lock
* around multiple operations to ensure consistency. The lock is a
* recursive spin-lock (i.e shouldn't be held for extended periods). */
+ (void)lock;
+ (void)unlock;
/* Accessors for the "animationDuration" per-thread transaction
* property. Defines the default duration of animations added to
* layers. Defaults to 1/4s. */
+ (CFTimeInterval)animationDuration;
+ (void)setAnimationDuration:(CFTimeInterval)dur;
/* Accessors for the "animationTimingFunction" per-thread transaction
* property. The default value is nil, when set to a non-nil value any
* animations added to layers will have this value set as their
* "timingFunction" property. Added in Mac OS X 10.6. */
+ (nullable CAMediaTimingFunction *)animationTimingFunction;
+ (void)setAnimationTimingFunction:(nullable CAMediaTimingFunction *)function;
/* Accessors for the "disableActions" per-thread transaction property.
* Defines whether or not the layer's -actionForKey: method is used to
* find an action (aka. implicit animation) for each layer property
* change. Defaults to NO, i.e. implicit animations enabled. */
+ (BOOL)disableActions;
+ (void)setDisableActions:(BOOL)flag;
/* Accessors for the "completionBlock" per-thread transaction property.
* Once set to a non-nil value the block is guaranteed to be called (on
* the main thread) as soon as all animations subsequently added by
* this transaction group have completed (or been removed). If no
* animations are added before the current transaction group is
* committed (or the completion block is set to a different value), the
* block will be invoked immediately. Added in Mac OS X 10.6. */
#if __BLOCKS__
+ (nullable void (^)(void))completionBlock;
+ (void)setCompletionBlock:(nullable void (^)(void))block;
#endif
/* Associate arbitrary keyed-data with the current transaction (i.e.
* with the current thread).
*
* Nested transactions have nested data scope, i.e. reading a key
* searches for the innermost scope that has set it, setting a key
* always sets it in the innermost scope.
*
* Currently supported transaction properties include:
* "animationDuration", "animationTimingFunction", "completionBlock",
* "disableActions". See method declarations above for descriptions of
* each property.
*
* Attempting to set a property to a type other than its document type
* has an undefined result. */
+ (nullable id)valueForKey:(NSString *)key;
+ (void)setValue:(nullable id)anObject forKey:(NSString *)key;
事務(wù)有顯式事務(wù)和隱式事務(wù)之分
Core Animation在每個(gè)run loop周期中自動(dòng)開始一次新的事務(wù)，即使你不顯式的用[CATransaction begin]開始一次事務(wù)，任何在一次run loop循環(huán)中圖層屬性的改變都會(huì)被集中起來，然后做一次0.25秒的動(dòng)畫，即隱式事務(wù)
調(diào)用[CATransaction begin]開始一次事務(wù)，即為顯式事務(wù)
舉個(gè)栗子，新開一個(gè)事務(wù)，修改layer的backgroundColor:
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
//修改動(dòng)畫的持續(xù)時(shí)間
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"動(dòng)畫完成");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
running.gif
UIView中也有類似的動(dòng)畫機(jī)制：
+ (void)beginAnimations:(nullable NSString *)animationID context:(nullable void *)context; // additional context info passed to will start/did stop selectors. begin/commit can be nested
+ (void)commitAnimations; // starts up any animations when the top level animation is commited
iOS 4中引入了block：
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations NS_AVAILABLE_IOS(4_0); // delay = 0.0, options = 0, completion = NULL
其實(shí)兩者都在做同樣的事，block形式的寫法更為簡潔
CATransaction的+begin和+commit方法在+animateWithDuration:animations:內(nèi)部自動(dòng)調(diào)用，這樣block中所有屬性的改變都會(huì)被事務(wù)所包含，也可以避免開發(fā)者由于對+begin和+commit匹配的失誤造成的風(fēng)險(xiǎn)
行為：
為毛我修改layer的backgroundColor，隱式動(dòng)畫的效果一直是漸變呢，為毛不能是淡入淡出或其他效果呢？這就要看圖層的行為了
圖層行為，實(shí)質(zhì)上是如下幾步：
- 圖層首先檢測它是否有委托，并且是否實(shí)現(xiàn)CALayerDelegate協(xié)議指定的-actionForLayer:forKey:方法，如果有，直接調(diào)用并返回結(jié)果
- 如果沒有委托，或者委托沒有實(shí)現(xiàn)-actionForLayer:forKey:方法，圖層接著檢查包含屬性名稱對應(yīng)行為映射的actions字典
- 如果actions字典沒有包含對應(yīng)的屬性，那么圖層接著在它的style字典接著搜索屬性名
- 最后，如果在style里面也找不到對應(yīng)的行為，那么圖層將會(huì)直接調(diào)用定義了每個(gè)屬性的標(biāo)準(zhǔn)行為的-defaultActionForKey:方法
我們一步一步試一下：
- 圖層首先檢測它是否有委托，并且是否實(shí)現(xiàn)CALayerDelegate協(xié)議指定的-actionForLayer:forKey:方法，如果有，直接調(diào)用并返回結(jié)果
-(void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
[self.view.layer addSublayer:layer];
}
-(id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event{
NSLog(@"event is : %@",event);
CATransition *transition = [CATransition animation];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromLeft;
return transition;
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
-actionForLayer:forKey:需要返回一個(gè)遵守<CAAction>協(xié)議的對象，這個(gè)對象定義了圖層的行為
CATransition遵守<CAAction>協(xié)議，可以用于創(chuàng)建過渡動(dòng)畫，并返回給圖層
CATransition是另一個(gè)CAAnimation的子類，和別的子類不同，CATransition有一個(gè)type和subtype來標(biāo)識(shí)變換效果，type屬性是一個(gè)NSString類型，可以被設(shè)置成如下類型：
/* Common transition types. */
CA_EXTERN NSString * const kCATransitionFade
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionMoveIn
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionPush
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionReveal
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
subtype用來控制動(dòng)畫方向，提供了如下四種類型：
/* Common transition subtypes. */
CA_EXTERN NSString * const kCATransitionFromRight
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromLeft
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromTop
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
CA_EXTERN NSString * const kCATransitionFromBottom
CA_AVAILABLE_STARTING (10.5, 2.0, 9.0, 2.0);
running.gif
- 如果沒有委托，或者委托沒有實(shí)現(xiàn)-actionForLayer:forKey:方法，圖層接著檢查包含屬性名稱對應(yīng)行為映射的actions字典
-(void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
CATransition *transition = [CATransition animation];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromRight;
layer.actions = @{@"backgroundColor":transition};
[self.view.layer addSublayer:layer];
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
}];
layer.backgroundColor = [UIColor blueColor].CGColor;
[CATransaction commit];
}
running.gif
- 如果actions字典沒有包含對應(yīng)的屬性，那么圖層接著在它的style字典接著搜索屬性名
layer.style = @{@"backgroundColor":transition};
當(dāng)我給layer的style賦值的時(shí)候，卻并沒有效果，不知道為什么了，愿知道的大神留言教我??
呈現(xiàn)圖層
當(dāng)你改變一個(gè)圖層的屬性，屬性值的確是立刻更新的（如果你讀取它的數(shù)據(jù)，你會(huì)發(fā)現(xiàn)它的值在你設(shè)置它的那一刻就已經(jīng)生效了），但是屏幕上并沒有馬上發(fā)生改變。這是因?yàn)槟阍O(shè)置的屬性并沒有直接調(diào)整圖層的外觀，相反，他只是定義了圖層動(dòng)畫結(jié)束之后將要變化的外觀
如果你想讀取正在動(dòng)畫中的圖層的當(dāng)前屬性值，得用這個(gè)
/* Returns a copy of the layer containing all properties as they were
* at the start of the current transaction, with any active animations
* applied. This gives a close approximation to the version of the layer
* that is currently displayed. Returns nil if the layer has not yet
* been committed.
*
* The effect of attempting to modify the returned layer in any way is
* undefined.
*
* The `sublayers', `mask' and `superlayer' properties of the returned
* layer return the presentation versions of these properties. This
* carries through to read-only layer methods. E.g., calling -hitTest:
* on the result of the -presentationLayer will query the presentation
* values of the layer tree. */
- (nullable instancetype)presentationLayer;
舉個(gè)栗子：
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];
layer = [CALayer layer];
layer.backgroundColor = [UIColor redColor].CGColor;
layer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);
layer.position = self.view.layer.position;
layer.delegate = self;
[self.view.layer addSublayer:layer];
}
-(void)timerAction{
NSLog(@"presentationLayer.position = %@\tlayer.position = %@",NSStringFromCGPoint(layer.presentationLayer.position),NSStringFromCGPoint(layer.position));
}
//-(id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event{
// NSLog(@"event is : %@",event);
// CATransition *transition = [CATransition animation];
// transition.type = kCATransitionPush;
// transition.subtype = kCATransitionFromLeft;
// return transition;
//}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
[super touchesBegan:touches withEvent:event];
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:.5f target:self selector:@selector(timerAction) userInfo:nil repeats:YES];
[CATransaction begin];
[CATransaction setAnimationDuration:5.0f];
[CATransaction setCompletionBlock:^{
NSLog(@"completion");
[timer invalidate];
}];
layer.position = CGPointMake(0.0f, 0.0f);
[CATransaction commit];
}
輸出：
屏幕快照 2017-03-09 下午4.09.50.png
但是當(dāng)我改變layer的默認(rèn)行為的時(shí)候(就是注釋的那部分)，presentationLayer就不能獲取到正確的值了
