getClip method

@override Path getClip(Size size)

Returns a description of the clip given that the render object being clipped is of the given size.

Implementation

@override
Path getClip(Size size) {
  final double w = size.width;
  final double h = size.height;
  final Path path = Path();

  //每组波浪的数量
  final int everyGroupWaveCount = (w / waveWidth).ceil();

  //波浪虚拟数量
  //2代表只准备两组循环利用
  final int waveCount = 2 * everyGroupWaveCount;

  path.moveTo(0, -waveHeight);
  for (int i = 0; i < waveCount; i++) {
    path.relativeQuadraticBezierTo(
        waveWidth / 2, -waveHeight * 2, waveWidth, 0);
    path.relativeQuadraticBezierTo(
        waveWidth / 2, waveHeight * 2, waveWidth, 0);
  }
  path.lineTo(waveWidth * waveCount * 2, h);
  path.lineTo(0, h);
  path.close();

  //波浪总数量
  final int totalCount = waveSpeed * everyGroupWaveCount;

  if (waveAlignment == WaveAlignment.right) {
    //波浪往右
    //波浪总宽度
    final double waveTotalWidth = totalCount * waveWidth;
    return path.shift(
      Offset(
        -waveTotalWidth * (1 - animation.value),
        (h + waveHeight * 2) * (1 - animation.value),
      ),
    );
  }

  return path.shift(
    Offset(
      -waveWidth * ((totalCount * animation.value) % 2),
      (h + waveHeight * 2) * (1 - animation.value),
    ),
  );
}