Class for coordinate transforms between coordinate systems. Depends on the proj4js library. If proj4js is not available, then this is just an empty stub.
| OpenLayers. | Class for coordinate transforms between coordinate systems. |
| Properties | |
| proj | {Object} Proj4js.Proj instance. |
| projCode | {String} |
| titleRegEx | {RegExp} regular expression to strip the title from a proj4js definition |
| Constructor | |
| OpenLayers. | This class offers several methods for interacting with a wrapped pro4js projection object. |
| Functions and Properties | |
| getCode | Get the string SRS code. |
| getUnits | Get the units string for the projection -- returns null if proj4js is not available. |
| toString | Convert projection to string (getCode wrapper). |
| equals | Test equality of two projection instances. |
| destroy | Destroy projection object. |
| transforms | Transforms is an object, with from properties, each of which may have a to property. |
| addTransform | Set a custom transform method between two projections. |
| transform | Transform a point coordinate from one projection to another. |
| nullTransform |
This class offers several methods for interacting with a wrapped pro4js projection object.
| projCode | {String} A string identifying the Well Known Identifier for the projection. |
| options | {Object} An optional object to set additional properties on the layer. |
{OpenLayers.Projection} A projection object.
Transforms is an object, with from properties, each of which may have a to property. This allows you to define projections without requiring support for proj4js to be included.
This object has keys which correspond to a ‘source’ projection object. The keys should be strings, corresponding to the projection.getCode() value. Each source projection object should have a set of destination projection keys included in the object.
Each value in the destination object should be a transformation function, where the function is expected to be passed an object with a .x and a .y property. The function should return the object, with the .x and .y transformed according to the transformation function.
| Note | Properties on this object should not be set directly. To add a transform method to this object, use the addTransform method. For an example of usage, see the OpenLayers.Layer.SphericalMercator file. |
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.
| 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. |
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.
| 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 |
| point | {object} A transformed coordinate. The original point is modified. |
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);Get the string SRS code.
getCode: function()
Get the units string for the projection -- returns null if proj4js is not available.
getUnits: function()
Convert projection to string (getCode wrapper).
toString: function()
Test equality of two projection instances.
equals: function( projection )
Destroy projection object.
destroy: function()
Set a custom transform method between two projections.
OpenLayers.Projection.addTransform = function( from, to, method )
Transform a point coordinate from one projection to another.
OpenLayers.Projection.transform = function( point, source, dest )
OpenLayers.Projection.nullTransform = function( point )