自定義波浪線，待改進

基本思路：貝塞爾三階曲線

public class WaveView extends View {

    private float mCenterX;
    private float mCenterY;
    private float startX;
    private float startY;
    private float endX;
    private float endY;
    private float controlX1;
    private float controlX2;
    private float controlY1;
    private float controlY2;

    private float wave1;
    private float wave2;

    private Paint paint;
    private Paint arcPaint;

    public WaveView(Context context) {
        this(context, null);
    }

    public WaveView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public WaveView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        ObjectAnimator animator = ObjectAnimator.ofFloat(this, "wave", 0, 3000);
        animator.setDuration(4000);
        animator.setRepeatMode(ValueAnimator.INFINITE);
        animator.setRepeatCount(ValueAnimator.INFINITE);
        animator.start();

        paint = new Paint();
        paint.setColor(Color.BLUE);
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeCap(Paint.Cap.ROUND);

        arcPaint = new Paint();
        arcPaint.setStyle(Paint.Style.FILL);
        arcPaint.setStrokeCap(Paint.Cap.ROUND);
        arcPaint.setStrokeWidth(10);
    }

    public float getWave() {
        return wave1;
    }

    public void setWave(float wave) {
        this.wave1 = wave;
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mCenterX = canvas.getWidth() / 2;
        mCenterY = canvas.getHeight() / 2;
        startX = 0;
        startY = mCenterY;
        endX = mCenterX * 2;
        endY = mCenterY;

        controlX2 = mCenterX + wave1 > mCenterX * 2 ? (mCenterX + wave1) % canvas.getWidth() : mCenterX + wave1;
        controlY2 = mCenterY + 100;
        controlX1 = controlX2 - 300;
        controlY1 = mCenterY - 100;

        canvas.drawPoint(mCenterX, mCenterY, arcPaint);
        canvas.drawPoint(controlX1, controlY1, arcPaint);
        canvas.drawPoint(controlX2, controlY2, arcPaint);
        Path path = new Path();
        path.moveTo(startX, mCenterY);
        path.cubicTo(controlX1, controlY1, controlX2, controlY2, endX, mCenterY);
        canvas.drawPath(path, paint);

    }
}