Position class abstract

A base class for geospatial positions.

The known two instantiable sub classes are Projected (with x, y, z and m coordinates) and Geographic (with lon, lat, elev and m coordinates).

It's also possible to create a position using factory methods Position.view, Position.create and Position.parse that create an instance storing coordinate values in a double array.

All implementations must contain at least x and y coordinate values, but z and m coordinates are optional (getters should return zero value when such a coordinate axis is not available).

When a position contains geographic coordinates, then by default x represents longitude, y represents latitude, and z represents elevation (or height or altitude).

A projected map position might be defined as easting (E) and northing (N) coordinates. It's suggested that then E == x and N == y, but a coordinate reference system might specify something else too.

m represents a measurement or a value on a linear referencing system (like time). It could be associated with a 2D position (x, y, m) or a 3D position (x, y, z, m).

For 2D coordinates the coordinate axis indexes are:

Index	Projected	Geographic
0	x	lon
1	y	lat
2	m	m

For 3D coordinates the coordinate axis indexes are:

Index	Projected	Geographic
0	x	lon
1	y	lat
2	z	elev
3	m	m

Sub classes containing coordinate values mentioned above, should implement equality and hashCode methods as:

@override
bool operator ==(Object other) =>
     other is Position && Position.testEquals(this, other);

@override
int get hashCode => Position.hash(this);

Inheritance

Implementers

Constructors

Position(): Default const constructor to allow extending this abstract class.
const
Position.create({required double x, required double y, double? z, double? m}): A position from parameters compatible with CreatePosition function type.
factory
Position.parse(String text, {Pattern delimiter = ',', Coords? type, bool swapXY = false, bool singlePrecision = false}): Parses a position from text.
factory
Position.subview(List<double> source, {required int start, Coords type = Coords.xy}): A position with coordinate values as a sub view backed by source, starting at start.
factory
Position.view(List<double> source, {Coords? type}): A position with coordinate values as a view backed by source.
factory

Properties

conforming → PositionScheme: Returns a position scheme this position is conforming to.
no setter
coordinateDimension → int: The number of coordinate values (2, 3 or 4) on a position.
no setterinherited
coordType → Coords: A value of Coords representing the coordinate type of position data contained directly or within child objects.
no setterinherited
hashCode → int: The hash code for this object.
no setterinherited
is3D → bool: True for 3D positions (with z or elevation coordinate).
no setterinherited
isMeasured → bool: True if a measure value is available (or the m coordinate for a position).
no setterinherited
m → double: The m ("measure") coordinate value. Returns zero if not available.
no setter
optM → double?: The m ("measure") coordinate optionally. Returns null if not available.
no setter
optZ → double?: The z coordinate value optionally. Returns null if not available.
no setter
positionCount → int: A Position object represents a single position, returns always 1.
no setteroverride
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
spatialDimension → int: The number of spatial coordinate values (2 for 2D or 3 for 3D) on a position.
no setterinherited
type → Coords: The coordinate type.
no setterinherited
valueCount → int: The number of coordinate values contained.
no setterinherited
values → Iterable<double>: Coordinate values of this position as an iterable of 2, 3 or 4 items.
no setteroverride
x → double: The x coordinate value.
no setter
y → double: The y coordinate value.
no setter
z → double: The z coordinate value. Returns zero if not available.
no setter

Methods

bearingTo2D(Position destination) → double: Returns a bearing from this to destination calculated in a cartesian 2D plane.
copyByType(Coords type) → Position: Copies this as another object according to the given type.
override
copyTo<R extends Position>(CreatePosition<R> factory) → R: Copies this position to a new position created by the factory.
copyWith({double? x, double? y, double? z, double? m}) → Position: Copies the position with optional x, y, z and m overriding values.
destinationPoint2D({required double distance, required double bearing}) → Position: Returns a destination point located at the given distance from this to the direction of bearing calculated in a cartesian 2D plane.
distanceTo2D(Position destination) → double: Returns a distance from this to destination calculated in a cartesian 2D plane.
distanceTo3D(Position destination) → double: Returns a distance from this to destination calculated in a cartesian 3D space.
equals2D(covariant Position other, {double toleranceHoriz = defaultEpsilon}) → bool: True if this position equals with other by testing 2D coordinates only.
override
equals3D(covariant Position other, {double toleranceHoriz = defaultEpsilon, double toleranceVert = defaultEpsilon}) → bool: True if this position equals with other by testing 3D coordinates only.
override
equalsCoords(covariant Position other) → bool: True if this and the other position equals.
override
expand(ExpandPosition expand) → Iterable<Position>: Expands this position to an iterable of zero or more positions of using expand.
intermediatePointTo(Position destination, {required double fraction}) → Position: Returns an intermediate point at the given fraction between this and destination positions calculated in the cartesian coordinate reference system.
midPointTo(Position destination) → Position: Returns a midpoint between this and destination positions calculated in the cartesian coordinate reference system.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
packed() → Position: Returns a position instance whose coordinate storage contains only coordinate values represented by this position.
project(Projection projection) → Position: Projects this position to another position using projection.
override
toString() → String: A string representation of this object.
override
toText({String delimiter = ',', int? decimals, bool compactNums = true, bool swapXY = false}) → String: A string representation of coordinate values separated by delimiter.
override
transform(TransformPosition transform) → Position: Returns a position transformed from this using transform.
valuesByType(Coords type) → Iterable<double>: Coordinate values as a double iterable according to the given type.
override

Operators

operator %(Position divisor) → Position: Returns a position with coordinate values of this applied with modulo operator % by values of divisor.
operator *(double factor) → Position: Returns a position with coordinate values of this scaled by factor.
operator +(Position other) → Position: Returns a position with coordinate values summed from this and other.
operator -(Position other) → Position: Returns a position with coordinate values of this subtracted with values of other.
operator /(Position divisor) → Position: Returns a position with coordinate values of this divided by values of divisor.
operator ==(Object other) → bool: The equality operator.
inherited
operator [](int index) → double: A coordinate value by the coordinate axis index.
operator unary-() → Position: Returns a position with coordinate values of this negated.

Static Methods

buildPosition<R extends Position>(Iterable<num> coords, {required CreatePosition<R> to, int offset = 0, Coords? type, bool swapXY = false}) → R: Builds a position of R from coords starting from offset.
createFromObject<R extends Position>(Object position, {required CreatePosition<R> to, Coords? type}) → R: Creates a position of R from position (of R or Iterable<num>).
getValue(Position position, int index) → double: A coordinate value of position by the coordinate axis index.
getValues(Position position, {required Coords type}) → Iterable<double>: Coordinate values of position as an iterable of 2, 3 or 4 items.
hash(Position position) → int: The hash code for position.
override
parsePosition<R extends Position>(String text, {required CreatePosition<R> to, Pattern delimiter = ',', Coords? type, bool swapXY = false}) → R: Parses a position of R from text.
testEquals(Position p1, Position p2) → bool: True if positions p1 and p2 equals by testing all coordinate values.
testEquals2D(Position p1, Position p2, {double toleranceHoriz = defaultEpsilon}) → bool: True if positions p1 and p2 equals by testing 2D coordinates only.
testEquals3D(Position p1, Position p2, {double toleranceHoriz = defaultEpsilon, double toleranceVert = defaultEpsilon}) → bool: True if positions p1 and p2 equals by testing 3D coordinates only.
writeValues(Position position, StringSink buffer, {String delimiter = ',', int? decimals, bool compactNums = true, bool swapXY = false}) → void: Writes coordinate values of position to buffer separated by delimiter.

Constants

scheme → const PositionScheme: A position scheme that creates base Position and Box instances for positions and bounding boxes.