public class WaveView extends View {  private Paint mPaint;  private final Path mPath;  //波長  private int wavelength = 500;  private int originY=800;  private int dx,dy;   public WaveView(Context context, @Nullable AttributeSet attrs) {    super(context, attrs);    mPaint = new Paint();    mPath = new Path();    mPaint.setColor(Color.GREEN);    mPaint.setStrokeWidth(5);    mPaint.setStyle(Paint.Style.FILL_AND_STROKE);//    startanimation();  }    @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    //重置path    mPath.reset();//    改變y的起始坐標    if(dy<originY+150){      dy+=10;    }     int halfWaveLength = wavelength / 2;    mPath.moveTo(-wavelength + dx, originY-dy);    //屏幕多寬，畫多少    for (int i = -wavelength; i <= getWidth() + wavelength; i += wavelength) {      /**       * 相對繪制二階貝塞爾曲線（相對于自己的起始點--也即是上一個曲線的終點 ）       * float dx1 相對于上一個曲線的終點 的距離       * float dy1       * float dx2       * float dy2       */      mPath.rQuadTo(halfWaveLength / 2, -150, halfWaveLength, 0);      mPath.rQuadTo(halfWaveLength / 2, 150, halfWaveLength, 0);     }    //顏色填充    //畫一個封閉的空間    mPath.lineTo(getWidth(), getHeight());    mPath.lineTo(0, getHeight());    mPath.close();    canvas.drawPath(mPath, mPaint);//    //設置起始點坐標//    path.moveTo(100,400);//    //二階貝塞爾曲線1//    path.quadTo(250,200,400,400);//    //二階貝塞爾曲線2//    path.quadTo(550,600,700,400);//    //關閉路徑（將起點和終點閉合）//    path.close();//    path.moveTo(100,700);//    path.cubicTo(50,500,550,500,700,700);   }   public void startanimation() {    ValueAnimator animator = ValueAnimator.ofInt(0, wavelength);    animator.setDuration(1000);    animator.setInterpolator(new LinearInterpolator());    //無限循環    animator.setRepeatCount(ValueAnimator.INFINITE);    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {      @Override      public void onAnimationUpdate(ValueAnimator animation) {        dx = (int) animation.getAnimatedValue();        postInvalidate();      }    });    animator.start();  }}