GeoProjection class Projections

Projections transform spherical polygonal geometry to planar polygonal geometry.

D4 provides implementations of several classes of standard projections:

You can implement custom projections using GeoProjection or GeoProjectionMutator.

Implemented types

Implementers

Constructors

GeoProjection.new(GeoRawProjection project): Constructs a new projection from the specified raw projection, project. The project function takes the longitude and latitude of a given point in radians, often referred to as lambda (λ) and phi (φ), and returns a two-element list [x, y] representing its unit projection. The project function does not need to scale or translate the point, as these are applied automatically by scale, translate, and center. Likewise, the project function does not need to perform any spherical rotation, as rotate is applied prior to projection.

angle ↔ double: The projection's post-projection planar rotation angle in degrees.
getter/setter pair
center ↔ List<double>: The projection's center.
getter/setter pair
clipAngle ↔ double?: The projection's small-circle clipping radius angle in degrees.
getter/setter pair
clipExtent ↔ List<List<double>>?: The projection's viewport clipping extent bounds in pixels.
getter/setter pair
hashCode → int: The hash code for this object.
no setterinherited
postclip ↔ GeoStream Function(GeoStream): The projection's cartesian clipping.
getter/setter pair
precision ↔ double: The projection’s adaptive resampling threshold in pixels.
getter/setter pair
preclip ↔ GeoStream Function(GeoStream): The projection's spherical clipping.
getter/setter pair
reflectX ↔ bool: The projection's x-reflection state.
getter/setter pair
reflectY ↔ bool: The projection's x-reflection state.
getter/setter pair
rotate ↔ List<double>: The projection's three-axis spherical rotation angles.
getter/setter pair
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
scale ↔ double: The projection's scale factor.
getter/setter pair
translate ↔ List<double>: The projection's translation offset.
getter/setter pair

call(List<num> point) → List<num>?: Returns a new list [x, y] (typically in pixels) representing the projected point of the given point.
fitExtent(List<List<double>> extent, Map object) → void: Sets the projection’s scale and translate to fit the specified GeoJSON object in the center of the given extent.
fitHeight(double height, Map object) → void: A convenience method for fitSize where the width is automatically chosen from the aspect ratio of object and the given constraint on height.
fitSize(List<double> size, Map object) → void: A convenience method for fitExtent where the top-left corner of the extent is [0, 0].
fitWidth(double width, Map object) → void: A convenience method for fitSize where the height is automatically chosen from the aspect ratio of object and the given constraint on width.
invert(List<num> point) → List<num>?: Returns a new list [longitude, latitude] in degrees representing the unprojected point of the given projected point.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
stream(GeoStream stream) → GeoStream: Returns a projection stream for the specified stream.
override
toString() → String: A string representation of this object.
inherited