Android动画深入分析详解手机开发

public static interface AnimatorListener { 
    void onAnimationStart(Animator animation); //动画开始 
    void onAnimationEnd(Animator animation); //动画结束 
    void onAnimationCancel(Animator animation); //动画取消 
    void onAnimationRepeat(Animator animation); //动画重复播放 
}

AnimatorUpdateListener

public static interface AnimatorUpdateListener { 
    void onAnimationUpdate(ValueAnimator animator); 
}

应用场景

private void start(boolean playBackwards) { 
        if(Looper.myLooper() == null) { 
            throw new AndroidRuntimeException("Animators may only be run on Looper threads"); 
        } else { 
            this.mPlayingBackwards = playBackwards; 
            this.mCurrentIteration = 0; 
            this.mPlayingState = 0; 
            this.mStarted = true; 
            this.mStartedDelay = false; 
            ((ArrayList)sPendingAnimations.get()).add(this); 
            if(this.mStartDelay == 0L) { 
                this.setCurrentPlayTime(this.getCurrentPlayTime()); 
                this.mPlayingState = 0; 
                this.mRunning = true; 
                if(this.mListeners != null) { 
                    ArrayList animationHandler = (ArrayList)this.mListeners.clone(); 
                    int numListeners = animationHandler.size(); 
 
                    for(int i = 0; i < numListeners; ++i) { 
                        ((AnimatorListener)animationHandler.get(i)).onAnimationStart(this); 
                    } 
                } 
            } 
 
            ValueAnimator.AnimationHandler var5 = (ValueAnimator.AnimationHandler)sAnimationHandler.get(); 
            if(var5 == null) { 
                var5 = new ValueAnimator.AnimationHandler(null); 
                sAnimationHandler.set(var5); 
            } 
 
            var5.sendEmptyMessage(0); 
        } 
    }

 private static final ThreadLocal<ArrayList<ValueAnimator>> sAnimations = new ThreadLocal() { 
        protected ArrayList<ValueAnimator> initialValue() { 
            return new ArrayList(); 
        } 
    }; 
    private static final ThreadLocal<ArrayList<ValueAnimator>> sPendingAnimations = new ThreadLocal() { 
        protected ArrayList<ValueAnimator> initialValue() { 
            return new ArrayList(); 
        } 
    }; 
    private static final ThreadLocal<ArrayList<ValueAnimator>> sDelayedAnims = new ThreadLocal() { 
        protected ArrayList<ValueAnimator> initialValue() { 
            return new ArrayList(); 
        } 
    }; 
    private static final ThreadLocal<ArrayList<ValueAnimator>> sEndingAnims = new ThreadLocal() { 
        protected ArrayList<ValueAnimator> initialValue() { 
            return new ArrayList(); 
        } 
    }; 
    private static final ThreadLocal<ArrayList<ValueAnimator>> sReadyAnims = new ThreadLocal() { 
        protected ArrayList<ValueAnimator> initialValue() { 
            return new ArrayList(); 
        } 
    };

这里系统怎么计算每一帧的动画的呢，看看下面的代码

void animateValue(float fraction) {         fraction = this.mInterpolator.getInterpolation(fraction);         this.mCurrentFraction = fraction;         int numValues = this.mValues.length;          int numListeners;         for(numListeners = 0; numListeners < numValues; ++numListeners) {             this.mValues[numListeners].calculateValue(fraction);         }          if(this.mUpdateListeners != null) {             numListeners = this.mUpdateListeners.size();              for(int i = 0; i < numListeners; ++i) {                 ((ValueAnimator.AnimatorUpdateListener)this.mUpdateListeners.get(i)).onAnimationUpdate(this);             }         }      }

不过我们知道要改变动画，一定调用了get/set方法，那我们重点看下这相关的代码。这段代码在setProperty方法里面

 public void setProperty(Property property) {         if(this.mValues != null) {             PropertyValuesHolder valuesHolder = this.mValues[0];             String oldName = valuesHolder.getPropertyName();             valuesHolder.setProperty(property);             this.mValuesMap.remove(oldName);             this.mValuesMap.put(this.mPropertyName, valuesHolder);         }          if(this.mProperty != null) {             this.mPropertyName = property.getName();         }          this.mProperty = property;         this.mInitialized = false;     }

这里有一个PropertyValuesHolder，顾名思义这是一个操作数据的类，和我们的adapter的Holder差不多，该方法的get方法主要用到了反射。

 private void setupValue(Object target, Keyframe kf) { 
        if(this.mProperty != null) { 
            kf.setValue(this.mProperty.get(target)); 
        } 
 
        try { 
            if(this.mGetter == null) { 
                Class e = target.getClass(); 
                this.setupGetter(e); 
            } 
 
            kf.setValue(this.mGetter.invoke(target, new Object[0])); 
        } catch (InvocationTargetException var4) { 
            Log.e("PropertyValuesHolder", var4.toString()); 
        } catch (IllegalAccessException var5) { 
            Log.e("PropertyValuesHolder", var5.toString()); 
        } 
 
    }

代码就看到这，有兴趣的可以去看下源码