Module: ol/proj

Functions

addCoordinateTransforms(source, destination, forward, inverse)

proj.js, line 413

import {addCoordinateTransforms} from 'ol/proj';

Registers coordinate transform functions to convert coordinates between the source projection and the destination projection. The forward and inverse functions convert coordinate pairs; this function converts these into the functions used internally which also handle extents and coordinate arrays.

Name	Type	Description
source	ProjectionLike	Source projection.
destination	ProjectionLike	Destination projection.
forward	function	The forward transform function (that is, from the source projection to the destination projection) that takes a Coordinate as argument and returns the transformed Coordinate.
inverse	function	The inverse transform function (that is, from the destination projection to the source projection) that takes a Coordinate as argument and returns the transformed Coordinate. If the transform function can only transform less dimensions than the input coordinate, it is supposeed to return a coordinate with only the length it can transform. The other dimensions will be taken unchanged from the source.

addEquivalentProjections(projections)

proj.js, line 297

import {addEquivalentProjections} from 'ol/proj';

Registers transformation functions that don't alter coordinates. Those allow to transform between projections with equal meaning.

Name	Type	Description
projections	Array<Projection>	Projections.

addProjection(projection)

proj.js, line 177

import {addProjection} from 'ol/proj';

Add a Projection object to the list of supported projections that can be looked up by their code.

Name	Type	Description
projection	Projection	Projection instance.

clearUserProjection()

proj.js, line 677

import {clearUserProjection} from 'ol/proj';

Clear the user projection if set.

equivalent(projection1, projection2){boolean}

proj.js, line 478

import {equivalent} from 'ol/proj';

Checks if two projections are the same, that is every coordinate in one projection does represent the same geographic point as the same coordinate in the other projection.

Name	Type	Description
projection1	Projection	Projection 1.
projection2	Projection	Projection 2.

Returns:

Equivalent.

fromLonLat(coordinate, projection){Coordinate}

proj.js, line 437

import {fromLonLat} from 'ol/proj';

Transforms a coordinate from longitude/latitude to a different projection.

Name	Type	Description
coordinate	Coordinate	Coordinate as longitude and latitude, i.e. an array with longitude as 1st and latitude as 2nd element.
projection	ProjectionLike | undefined	Target projection. The default is Web Mercator, i.e. 'EPSG:3857'.

Returns:

Coordinate projected to the target projection.

get(projectionLike){Projection | null}

proj.js, line 198

import {get} from 'ol/proj';

Fetches a Projection object for the code specified.

Name	Type	Description
projectionLike	ProjectionLike	Either a code string which is a combination of authority and identifier such as "EPSG:4326", or an existing projection object, or undefined.

Returns:

Projection object, or null if not in list.

getPointResolution(projection, resolution, point, units){number}

proj.js, line 235

import {getPointResolution} from 'ol/proj';

Get the resolution of the point in degrees or distance units. For projections with degrees as the unit this will simply return the provided resolution. For other projections the point resolution is by default estimated by transforming the point pixel to EPSG:4326, measuring its width and height on the normal sphere, and taking the average of the width and height. A custom function can be provided for a specific projection, either by setting the getPointResolution option in the Projection constructor or by using setGetPointResolution to change an existing projection object.

Name	Type	Description
projection	ProjectionLike	The projection.
resolution	number	Nominal resolution in projection units.
point	Coordinate	Point to find adjusted resolution at.
units	Units | undefined	Units to get the point resolution in. Default is the projection's units.

Returns:

Point resolution.

getTransform(source, destination){TransformFunction}

proj.js, line 586

import {getTransform} from 'ol/proj';

Given the projection-like objects, searches for a transformation function to convert a coordinates array from the source projection to the destination projection.

Name	Type	Description
source	ProjectionLike	Source.
destination	ProjectionLike	Destination.

Returns:

Transform function.

getUserProjection(){Projection | null}

proj.js, line 686

import {getUserProjection} from 'ol/proj';

Get the projection for coordinates supplied from and returned by API methods.

Returns:

The user projection (or null if not set).

setUserProjection(projection)

proj.js, line 669

import {setUserProjection} from 'ol/proj';

Set the projection for coordinates supplied from and returned by API methods. This includes all API methods except for those interacting with tile grids, plus FrameState and State.

Name	Type	Description
projection	ProjectionLike	The user projection.

toLonLat(coordinate, projection){Coordinate}

proj.js, line 455

import {toLonLat} from 'ol/proj';

Transforms a coordinate to longitude/latitude.

Name	Type	Description
coordinate	Coordinate	Projected coordinate.
projection	ProjectionLike | undefined	Projection of the coordinate. The default is Web Mercator, i.e. 'EPSG:3857'.

Returns:

Coordinate as longitude and latitude, i.e. an array with longitude as 1st and latitude as 2nd element.

transform(coordinate, source, destination){Coordinate}

proj.js, line 608

import {transform} from 'ol/proj';

Transforms a coordinate from source projection to destination projection. This returns a new coordinate (and does not modify the original). If there is no available transform between the two projection, the function will throw an error.

See transformExtent for extent transformation. See the transform method of Geometry and its subclasses for geometry transforms.

Name	Type	Description
coordinate	Coordinate	Coordinate.
source	ProjectionLike	Source projection-like.
destination	ProjectionLike	Destination projection-like.

Returns:

Coordinate.

transformExtent(extent, source, destination, stops){Extent}

proj.js, line 632

import {transformExtent} from 'ol/proj';

Transforms an extent from source projection to destination projection. This returns a new extent (and does not modify the original).

Name	Type	Description
extent	Extent	The extent to transform.
source	ProjectionLike	Source projection-like.
destination	ProjectionLike	Destination projection-like.
stops	number | undefined	Number of stops per side used for the transform. By default only the corners are used.

Returns:

The transformed extent.

useGeographic()

proj.js, line 696

import {useGeographic} from 'ol/proj';

Use geographic coordinates (WGS-84 datum) in API methods. This includes all API methods except for those interacting with tile grids, plus FrameState and State.

Type Definitions

ProjectionLike{Projection} {string} {undefined}

A projection as Projection, SRS identifier string or undefined.

TransformFunction(input, output, dimension, stride){Array.<number>}

proj.js, line 107

A transform function accepts an array of input coordinate values, an optional output array, and an optional dimension (default should be 2). The function transforms the input coordinate values, populates the output array, and returns the output array.

Name	Type	Description
input	Array.<number>
output	Array.<number> | undefined
dimension	number | undefined
stride	number | undefined

Transforms{Object}

Properties:

Name	Type	Description
forward	TransformFunction	The forward transform (from geographic).
inverse	TransformFunction	The inverse transform (to geographic).