build<T extends Geometry> static method

FeatureCollection<Feature<T>> build<T extends Geometry>(WriteFeatures features, { int? count, Box? bounds, Map<String, dynamic>? custom, })

Builds a feature collection from the content provided by features.

Feature items on a collection have an optional primary geometry of T.

Only Feature items of Feature<T> provided by features are built, any other objects are ignored.

An optional expected count, when given, specifies the number of feature objects in the content. Note that when given the count MUST be exact.

An optional bounds can used set a minimum bounding box for a feature collection.

Use an optional custom parameter to set any custom or "foreign member" properties.

Examples:

// a feature collection with two features
FeatureCollection.build(
  count: 2,
  (feat) => feat
    // a feature with an id and a point geometry (2D coordinates)
    ..feature(
      id: '1',
      geometry: (geom) => geom.point([10.0, 20.0].xy),
    )

    // a feature with properties and a line string geometry (3D)
    ..feature(
      geometry: (geom) => geom.lineString(
        // three (x, y, z) positions
        [10.0, 20.0, 30.0, 12.5, 22.5, 32.5, 15.0, 25.0, 35.0]
            .positions(Coords.xyz),
      ),
      // properties for a feature containing JSON Object like data
      properties: {
        'textProp': 'this is property value',
        'intProp': 10,
        'doubleProp': 29.5,
        'arrayProp': ['foo', 'bar'],
      },
    ),
);

Implementation

static FeatureCollection<Feature<T>> build<T extends Geometry>(
  WriteFeatures features, {
  int? count,
  Box? bounds,
  Map<String, dynamic>? custom,
}) {
  // NOTE: use optional count to create a list in right size at build start

  // build any feature items on a list
  final list =
      FeatureBuilder.buildList<Feature<T>, T>(features, count: count);

  // create a feature collection with features and optional custom props
  return FeatureCollection<Feature<T>>(
    list,
    custom: custom,
    bounds: bounds,
  );
}