OpenLayers.Projection

Class for coordinate transforms between coordinate systems. Depends on the proj4js library. If proj4js is not available, then this is just an empty stub.

Summary

OpenLayers.Projection	Class for coordinate transforms between coordinate systems.
Constructor
OpenLayers.Projection	This class offers several methods for interacting with a wrapped pro4js projection object.
Functions
getCode	Get the string SRS code.
getUnits	Get the units string for the projection -- returns null if proj4js is not available.
addTransform	Set a custom transform method between two projections.
transform	Transform a point coordinate from one projection to another.
nullTransform

Constructor

OpenLayers.Projection

This class offers several methods for interacting with a wrapped pro4js projection object.

Parameters

projCode	{String} A string identifying the Well Known Identifier for the projection.
options	{Object} An optional object to set additional properties on the layer.

Returns

{OpenLayers.Projection} A projection object.

Functions

getCode

getCode: function()

Get the string SRS code.

Returns

{String} The SRS code.

getUnits

getUnits: function()

Get the units string for the projection -- returns null if proj4js is not available.

Returns

{String} The units abbreviation.

addTransform

OpenLayers.Projection.addTransform = function( from,
to,
method )

Set a custom transform method between two projections. Use this method in cases where the proj4js lib is not available or where custom projections need to be handled.

Parameters

from	{String} The code for the source projection
to	{String} the code for the destination projection
method	{Function} A function that takes a point as an argument and transforms that point from the source to the destination projection in place. The original point should be modified.

transform

OpenLayers.Projection.transform = function( point,
source,
dest )

Transform a point coordinate from one projection to another. Note that the input point is transformed in place.

Parameters

point	{OpenLayers.Geometry.Point \| Object} An object with x and y properties representing coordinates in those dimensions.
source	{OpenLayers.Projection} Source map coordinate system
dest	{OpenLayers.Projection} Destination map coordinate system

Returns

point

{object} A transformed coordinate. The original point is modified.

nullTransform

OpenLayers.Projection.nullTransform = function( point )

A null transformation

useful for defining projection aliases when proj4js is not available:

OpenLayers.Projection.addTransform("EPSG:4326", "EPSG:3857",
    OpenLayers.Layer.SphericalMercator.projectForward);
OpenLayers.Projection.addTransform("EPSG:3857", "EPSG:3857",
    OpenLayers.Layer.SphericalMercator.projectInverse);
OpenLayers.Projection.addTransform("EPSG:3857", "EPSG:900913",
    OpenLayers.Projection.nullTransform);
OpenLayers.Projection.addTransform("EPSG:900913", "EPSG:3857",
    OpenLayers.Projection.nullTransform);