安卓动画学习笔记

一、Drawable Animation

也就是所谓的帧动画，Frame动画。指通过指定每一帧的图片和播放时间，有序的进行播放而形成动画效果。

二、View Animation

视图动画，也就是所谓补间动画，Tween动画。指通过指定View的初始状态、变化时间、方式，通过一系列的算法去进行图形变换，从而形成动画效果，主要有Alpha、Scale、Translate、Rotate四种效果。注意：只是在视图层实现了动画效果，并没有真正改变View的属性。

三、Property Animation

属性动画，通过不断的改变View的属性，不断的重绘而形成动画效果。相比于视图动画，View的属性是真正改变了。注意：Android 3.0(API 11)以上才支持。

anim文件夹下存放tween animation和frame animation；xml文件里只有scale、rotate、translate、alpha、set五个标签；在代码中使用AnimationUtils.loadAnimation（）方法加载；使用mView.setAnimation(mAnimation)为mView加载动画；使用mView.startAnimation()开启动画；

animator文件夹下存放property animation，即属性动画，xml文件里有animator、objectAnimator和set三个标签；在代码中使用AnimatorInflater.loadAnimator（）方法加载动画；使用mAnimation.setTarget（mView）为mView加载动画。使用mAnimation.start（）开启动画

animator代表的属性动画，每个动画只能改变一个属性值，如果需要改变多个可以考虑使用动画集。

补间动画和属性动画的区别

１．补间动画作用于view,不会改变view的属性，一个view对象有很多属性值，如:坐标，透明度等等，view的点击事件的有效点击区域并不会随着view的移动而发生改变

２．属性动画作用于view的属性，这些属性必须有get/set方法，要不属性动画将无法生效。

三种动画都是跑在UI线程中，也应了那句话，任何UI上的变化都发生在主线程中。主线程也只做更新UI的活。

/** * Start the animation playing. This version of start() takes a boolean flag that indicates * whether the animation should play in reverse. The flag is usually false, but may be set * to true if called from the reverse() method. * * <p>The animation started by calling this method will be run on the thread that called * this method. This thread should have a Looper on it (a runtime exception will be thrown if * this is not the case). Also, if the animation will animate * properties of objects in the view hierarchy, then the calling thread should be the UI * thread for that view hierarchy.</p> * * @param playBackwards Whether the ValueAnimator should start playing in reverse. */private void start(boolean playBackwards) {    if (Looper.myLooper() == null) {        throw new AndroidRuntimeException("Animators may only be run on Looper threads");    }    mReversing = playBackwards;    mPlayingBackwards = playBackwards;    if (playBackwards && mSeekFraction != -1) {        if (mSeekFraction == 0 && mCurrentIteration == 0) {            // special case: reversing from seek-to-0 should act as if not seeked at all            mSeekFraction = 0;        } else if (mRepeatCount == INFINITE) {            mSeekFraction = 1 - (mSeekFraction % 1);        } else {            mSeekFraction = 1 + mRepeatCount - (mCurrentIteration + mSeekFraction);        }        mCurrentIteration = (int) mSeekFraction;        mSeekFraction = mSeekFraction % 1;    }    if (mCurrentIteration > 0 && mRepeatMode == REVERSE &&            (mCurrentIteration < (mRepeatCount + 1) || mRepeatCount == INFINITE)) {        // if we were seeked to some other iteration in a reversing animator,        // figure out the correct direction to start playing based on the iteration        if (playBackwards) {            mPlayingBackwards = (mCurrentIteration % 2) == 0;        } else {            mPlayingBackwards = (mCurrentIteration % 2) != 0;        }    }    int prevPlayingState = mPlayingState;    mPlayingState = STOPPED;    mStarted = true;    mStartedDelay = false;    mPaused = false;    updateScaledDuration(); // in case the scale factor has changed since creation time    AnimationHandler animationHandler = getOrCreateAnimationHandler();    animationHandler.mPendingAnimations.add(this);    if (mStartDelay == 0) {        // This sets the initial value of the animation, prior to actually starting it running        if (prevPlayingState != SEEKED) {            setCurrentPlayTime(0);        }        mPlayingState = STOPPED;        mRunning = true;        notifyStartListeners();    }    animationHandler.start();}

Animation运行原理分析

http://www.cnblogs.com/kross/p/4087780.html

http://www.jianshu.com/p/fcd9c7e9937e