Android实现简单水波纹效果

public class WaveView extends View {
  private Paint mPaint;
  private final Path mPath;
  //波长
  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();
//    改变y的起始坐标
    if(dy<originY+150){
      dy+=10;
    }
 
    int halfWaveLength = wavelength / 2;
    mPath.moveTo(-wavelength + dx, originY-dy);
    //屏幕多宽，画多少
    for (int i = -wavelength; i <= getWidth() + wavelength; i += wavelength) {
      /**
       * 相对绘制二阶贝塞尔曲线（相对于自己的起始点--也即是上一个曲线的终点 ）
       * float dx1 相对于上一个曲线的终点 的距离
       * float dy1
       * float dx2
       * float dy2
       */
      mPath.rQuadTo(halfWaveLength / 2, -150, halfWaveLength, 0);
      mPath.rQuadTo(halfWaveLength / 2, 150, halfWaveLength, 0);
 
    }
    //颜色填充
    //画一个封闭的空间
    mPath.lineTo(getWidth(), getHeight());
    mPath.lineTo(0, getHeight());
    mPath.close();
    canvas.drawPath(mPath, mPaint);
//    //设置起始点坐标
//    path.moveTo(100,400);
//    //二阶贝塞尔曲线1
//    path.quadTo(250,200,400,400);
//    //二阶贝塞尔曲线2
//    path.quadTo(550,600,700,400);
//    //关闭路径（将起点和终点闭合）
//    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());
    //无限循环
    animator.setRepeatCount(ValueAnimator.INFINITE);
    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        dx = (int) animation.getAnimatedValue();
        postInvalidate();
      }
    });
    animator.start();
  }
}