Android自定义控件之三点依次变大并循环

在使用QQ浏览器的时候，发现下拉刷新时显示三点依次变大并且循环感觉蛮有趣的。在接触自定义View和属性动画后就一直想实现，那么现在就来看看如何实现。

一.自定义一个类MyPointView继承于View,在onDraw()方法里画圆点

public class MyPointView extends View {
    private MyPointViewEntity mPoint = new MyPointViewEntity(10);
    public MyPointView(Context context, AttributeSet attr) {
        super(context,attr);

    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (mPoint != null) {
            Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(Color.GRAY);
            paint.setStyle(Paint.Style.FILL);
            canvas.drawCircle(50, 50, mPoint.getmRadius(), paint);
        }
        super.onDraw(canvas);

    }

    void setPointRadius(int radius) {
    mPoint.setmRadius(radius);
        invalidate();
    }


}

其中 MyPointViewEntity是一个实体类，用于初始化圆点的半和设置圆点的半径，代码如下：

public class MyPointViewEntity {

        private int mRadius;

        public MyPointViewEntity(int mRadius) {
            this.mRadius = mRadius;
        }

        public int getmRadius() {
            return mRadius;
        }

        public void setmRadius(int mRadius) {
            this.mRadius = mRadius;
        }

}

二.在Activity里实现相应动画

public class ValueAnimatorActivity extends Activity {
    private Button mBtn;
    private MyPointView mPv;
    private MyPointView mPv1;
    private MyPointView mPv2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_valueanimator);
        mBtn = (Button) findViewById(R.id.btn);
        mPv = (MyPointView) findViewById(R.id.pointview);
        mPv1 = (MyPointView) findViewById(R.id.pointview1);
        mPv2 = (MyPointView) findViewById(R.id.pointview2);
        mBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                doObjectAnimator();
            }


        });
    }

    /*
    *ObjectAnimator(派生自ValueAnimator)
    */
    private void doObjectAnimator() {
        ObjectAnimator animator = ObjectAnimator.ofInt(mPv, "pointRadius", 15, 10);
        ObjectAnimator animator1 = ObjectAnimator.ofInt(mPv1, "pointRadius", 15, 10);
        ObjectAnimator animator2 = ObjectAnimator.ofInt(mPv2, "pointRadius", 15, 10);
        final AnimatorSet animSet = new AnimatorSet();
        animSet.play(animator).before(animator1);
        animSet.play(animator1).before(animator2);
        animSet.setDuration(300);
        animSet.start();
        animSet.addListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimation
Start(Animator animation) {

            }

            @Override
            public void onAnimationEnd(Animator animation) {
                animSet.start();
            }

            @Override
            public void onAnimationCancel(Animator animation) {

            }

            @Override
            public void onAnimationRepeat(Animator animation) {

            }
        });

    }}

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