属性动画的小球垂直下落与抛物线下落

public class MainActivity extends AppCompatActivity {

    private ImageView id_ball;

    private int heightPixels;

    //valueanimator实现的动画

    //不需要设置操作的属性,这就是和objectanimator的区别

    //好处,不需要操作对象的属性,一定要有getter和settter方法,可以根据当前动画的计算值,来操作任何属性

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        id_ball = (ImageView) findViewById(R.id.id_ball);
        //获取屏幕的高度
        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        //现实指标
        heightPixels = displayMetrics.heightPixels;
        id_ball.setOnClickListener(new View.OnClickListener() {
            @Override

            public void onClick(View view) {

                Toast .makeText(MainActivity.this,"123",Toast.LENGTH_SHORT).show();
            }
        });


    }
    // 抛物线
    public void paowuxian(View view) {
        //获取动画执行类,
        ValueAnimator valueAnimator = new ValueAnimator();
        //设置动画执行时间
        valueAnimator.setDuration(3000);
        //设置起始点
        valueAnimator.setObjectValues(new PointF(0, 0));
        //设置类型估值
        valueAnimator.setEvaluator(new TypeEvaluator<PointF>() {

            @Override
            public PointF evaluate(float v, PointF pointF, PointF t1) {
                PointF point = new PointF();
                point.x = 200 * v * 2;
                point.y = 0.5f * 200 * (v * 3) * (v * 2);
                return point;
            }
        });
        valueAnimator.start();

        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
        {
            @Override
            public void onAnimationUpdate(ValueAnimator animation)
            {
                PointF point = (PointF) animation.getAnimatedValue();
                id_ball.setX(point.x);
                id_ball.setY(point.y);

            }
        });


    }
            //垂直落下
    public void verticalRun(View view){
        //垂直//参数一:X起始位置,,参数二Y起始位置
        ValueAnimator animator = ValueAnimator.ofFloat(0, heightPixels - id_ball.getHeight());
        animator.setTarget(id_ball);
        animator.setDuration(3000).start();
//      animator.setInterpolator(value)
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener()
        {
            @Override
            public void onAnimationUpdate(ValueAnimator animation)
            {
                id_ball.setTranslationY((Float) animation.getAnimatedValue());

            }
        });
    }
  
}