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) {
  //基础数据
  final double w = size.width;
  final double h = size.height;
  final double r = _getDiagonal(size) / 2 + lensAperture;
  final Offset center = Offset(w / 2, h / 2);

  //准备叶片路径
  Path bladePath = Path();

  //起始点
  final Offset start =
      center.translate(-math.sqrt(3) / 2 * lensAperture, lensAperture / 2);
  bladePath.moveTo(start.dx, start.dy);

  //顶点
  final double b = math.sqrt(r * r + r - lensAperture * lensAperture);
  bladePath.lineTo(start.dx, start.dy - b);

  //画弧
  final double endX = r * (math.sqrt(3) / 2) + center.dx;
  final double endY = -r / 2 + center.dy;
  bladePath.arcToPoint(Offset(endX, endY), radius: Radius.circular(r));
  bladePath.close();

  //平移
  bladePath = bladePath.shift(Offset(0, -r * (1 - animation.value)));

  //准备联合路径
  Path path = bladePath;

  //循环联合路径
  for (int i = 1; i <= 5; i++) {
    final Matrix4 rM =
        Matrix4Transform().rotateDegrees(i * 60, origin: center).matrix4;
    path = Path.combine(
        PathOperation.union, path, bladePath.transform(rM.storage));
  }

  //镜头旋转
  final Matrix4 roate = Matrix4Transform()
      .rotateDegrees(lensAngle * animation.value, origin: center)
      .matrix4;
  return path.transform(roate.storage);
}