buildBox<R extends Box> static method

R buildBox<R extends Box>(Iterable<num> coords, { required CreateBox<R> to, int offset = 0, Coords? type, })

Builds a bounding box of R from coords starting from offset.

A bounding box instance is created using the factory function to.

Supported coordinate value combinations by coordinate type:

Type	Expected values
xy	minX, minY, maxX, maxY
xyz	minX, minY, minZ, maxX, maxY, maxZ
xym	minX, minY, minM, maxX, maxY, maxM
xyzm	minX, minY, minZ, minM, maxX, maxY, maxZ, maxM

Use an optional type to explicitely set the coordinate type. If not provided and coords has 6 items, then xyz coordinates are assumed.

Throws FormatException if coordinates are invalid.

Implementation

static R buildBox<R extends Box>(
  Iterable<num> coords, {
  required CreateBox<R> to,
  int offset = 0,
  Coords? type,
}) {
  if (coords is List<num>) {
    final len = coords.length - offset;
    final coordsType = type ?? Coords.fromDimension(math.min(4, len ~/ 2));
    final dim = coordsType.coordinateDimension;
    if (len < 2 * dim) {
      throw invalidCoordinates;
    }
    final mIndex = coordsType.indexForM;
    return to.call(
      minX: coords[offset],
      minY: coords[offset + 1],
      minZ: coordsType.is3D ? coords[offset + 2] : null,
      minM: mIndex != null ? coords[offset + mIndex] : null,
      maxX: coords[offset + dim],
      maxY: coords[offset + dim + 1],
      maxZ: coordsType.is3D ? coords[offset + dim + 2] : null,
      maxM: mIndex != null ? coords[offset + dim + mIndex] : null,
    );
  } else {
    // resolve iterator for source coordinates
    final Iterator<num> iter;
    if (offset == 0) {
      iter = coords.iterator;
    } else if (coords.length >= offset + 4) {
      iter = coords.skip(offset).iterator;
    } else {
      throw invalidCoordinates;
    }

    // must contain at least four numbers
    if (!iter.moveNext()) throw invalidCoordinates;
    final c0 = iter.current;
    if (!iter.moveNext()) throw invalidCoordinates;
    final c1 = iter.current;
    if (!iter.moveNext()) throw invalidCoordinates;
    final c2 = iter.current;
    if (!iter.moveNext()) throw invalidCoordinates;
    final c3 = iter.current;

    // rest 4 are optional, get first of them
    final c4 = iter.moveNext() ? iter.current : null;

    // if xy coordinates (4 items), then return already now
    if (type == Coords.xy || (c4 == null && type == null)) {
      return to.call(minX: c0, minY: c1, maxX: c2, maxY: c3);
    }

    // then get also last 3 of the optional
    final c5 = iter.moveNext() ? iter.current : null;
    final c6 = iter.moveNext() ? iter.current : null;
    final c7 = iter.moveNext() ? iter.current : null;

    // resolve coordinate type
    final Coords coordType;
    if (type != null) {
      // explicitely
      coordType = type;
    } else {
      // implicitely
      if (c4 != null && c5 != null) {
        coordType = c6 != null && c7 != null ? Coords.xyzm : Coords.xyz;
      } else {
        coordType = Coords.xy;
      }
    }

    // create bounding box depending on coordinate type
    switch (coordType) {
      case Coords.xy:
        if (c4 == null) {
          return to.call(minX: c0, minY: c1, maxX: c2, maxY: c3);
        }
        break;
      case Coords.xyz:
        if (c4 != null && c5 != null && c6 == null) {
          return to.call(
            minX: c0,
            minY: c1,
            minZ: c2,
            maxX: c3,
            maxY: c4,
            maxZ: c5,
          );
        }
        break;
      case Coords.xym:
        if (c4 != null && c5 != null && c6 == null) {
          return to.call(
            minX: c0,
            minY: c1,
            minM: c2,
            maxX: c3,
            maxY: c4,
            maxM: c5,
          );
        }
        break;
      case Coords.xyzm:
        if (c4 != null && c5 != null && c6 != null && c7 != null) {
          return to.call(
            minX: c0,
            minY: c1,
            minZ: c2,
            minM: c3,
            maxX: c4,
            maxY: c5,
            maxZ: c6,
            maxM: c7,
          );
        }
        break;
    }
    throw invalidCoordinates;
  }
}