Android动画系列之属性动画

1. 属性动画的常用设置
2. ValueAnimator
3. ObjectAnimator
4. 关键帧
5. 插值器和估值器

属性动画的常用设置

//设置属性动画持续时间
animator.setDuration(2000);
//设置属性插值器
animator.setInterpolator(new AccelerateInterpolator());
//设置属性动画重复播放模式
animator.setRepeatMode(ValueAnimator.REVERSE);
//设置属性动画重复播放次数
animator.setRepeatCount(0);
//设置属性动画延时播放的时间
animator.setStartDelay(0);
//设置属性动画估值器，用于控制最终属性值(API22)
animator.setCurrentFraction(0.5f);
//设置当前播放时间，其值在Duration范围之内
animator.setCurrentPlayTime(1000);
//设置属性动画估值器，用于控制最终属性值
animator.setEvaluator(new IntEvaluator());
//设置属性动画监听
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
    @Override
    public void onAnimationUpdate(ValueAnimator animation) {
        Log.i(TAG,animation.getAnimatedValue() + "");
        //
    }
});
//...

ValueAnimator

// The time interpolator to be used if none is set on the animation
private static final TimeInterpolator sDefaultInterpolator =
        new AccelerateDecelerateInterpolator();

void init() {
    if (mEvaluator == null) {
        // We already handle int and float automatically,but not their Object
        // equivalents
        mEvaluator = (mValueType == Integer.class) ? sIntEvaluator :
                (mValueType == Float.class) ? sFloatEvaluator :
                null;
    }
    if (mEvaluator != null) {
        // KeyframeSet knows how to evaluate the common types - only give it a custom
        // evaluator if one has been set on this class
        mKeyframes.setEvaluator(mEvaluator);
    }
}

使用代码创建

private void translation(){
    ValueAnimator valueAnimator = ValueAnimator.ofInt(0,100);
    valueAnimator.setDuration(2000);
    valueAnimator.setInterpolator(new AccelerateInterpolator());
    valueAnimator.setRepeatMode(ValueAnimator.REVERSE);
    valueAnimator.setRepeatCount(0);
    valueAnimator.setStartDelay(0);
//    valueAnimator.setCurrentFraction(0.5f);
//    valueAnimator.setCurrentPlayTime(1000);
    valueAnimator.setEvaluator(new IntEvaluator());

    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            Log.i(TAG,animation.getAnimatedValue() + "");
            int x = (int) animation.getAnimatedValue();
            ivImage.setTranslationX(x);
            ivImage.setTranslationY(x);
        }
    });

    valueAnimator.start();
}

使用xml创建

<?xml version="1.0" encoding="utf-8"?>
<animator xmlns:android="http://schemas.android.com/apk/res/android"
    android:valueFrom="0"
    android:valueTo="100"
    android:valueType="intType"

    android:duration="2000"
    android:startOffset ="0"
    android:repeatMode = "reverse"
    android:repeatCount = "0"
    android:interpolator = "@android:anim/accelerate_interpolator">
</animator>

private void translation(){
    ValueAnimator animator = (ValueAnimator) AnimatorInflater.loadAnimator(this,R.animator.test_animator);
    animator.setTarget(ivImage);
    animator.start();
    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            Log.i(TAG,animation.getAnimatedValue() + "");
            int x = (int) animation.getAnimatedValue();
            ivImage.setTranslationX(x);
            ivImage.setTranslationY(x);
        }
    });
}

测试效果

ObjectAnimator

private void alpha(){
    ObjectAnimator animator = ObjectAnimator.ofFloat(ivImage,"alpha",1f,1f);
    animator.setDuration(3000);
    //其他属性动画设置
    //...
    animator.start();
}

关键帧

/**
 * 关键帧的使用
 */
private void keyFrame(){
    Keyframe keyframe1 = Keyframe.ofFloat(0,0);
    Keyframe keyframe2 = Keyframe.ofFloat(0.25f,300);
    //每个KeyFrame可设置自己的插值器
    keyframe2.setInterpolator(new AccelerateInterpolator());
    Keyframe keyframe3 = Keyframe.ofFloat(0.75f,100);
    Keyframe keyframe4 = Keyframe.ofFloat(1,400);
    PropertyValuesHolder holder = PropertyValuesHolder.ofKeyframe("translationX",keyframe1,keyframe2,keyframe3,keyframe4);
    ObjectAnimator animator = ObjectAnimator.ofPropertyValuesHolder(ivImage,holder);
    animator.setDuration(3000);
    animator.start();
}

插值器和估值器

• 插值器(TimeInterpolator) 表示的是整个动画期间动画的变化规律，如加速、减速等。

• 估值器(TypeEvaluator)表示的是在整个动画期间各时刻属性值的具体变化。

/**
 * 自定义估值器
 * Point封装了坐标x和y
 */
public class SineTypeValue implements TypeEvaluator<Point> {
    @Override
    public Point evaluate(float fraction,Point startValue,Point endValue) {
        //y = sinA
        float distance = fraction * (endValue.getX() - startValue.getX());
        float x = startValue.getX() + distance;
        float y = startValue.getY() + (float) Math.sin(distance / 100 * Math.PI) * 100;
        Point point = new Point();
        point.setX(x);
        point.setY(y);
        return point;
    }
}

/**
 * 自定义估值器的使用
 * 正弦运动的估值器
 */
private void sina(){
    Point startPoint = new Point(ivImage.getX(),ivImage.getY());
    Point endPoint = new Point(ivImage.getX()+500,ivImage.getY());
    ValueAnimator valueAnimator = ValueAnimator.ofObject(new SineTypeValue(),startPoint,endPoint);
    valueAnimator.setDuration(5000);
    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            Log.i(TAG,animation.getAnimatedValue() + "");
            Point point = (Point) animation.getAnimatedValue();
            ivImage.setX(point.getX());
            ivImage.setY(point.getY());
        }
    });
    valueAnimator.start();
}