Currently, there are a number of applications where client-side reprojection support is useful. Many users expect lat/lon coordinates to be displayed (rather than projected coordinates). This requires reprojecting from the map's internal projection to lat/lon for the user. Also, with the new sphericalmercator work expecially, many users want to be able to load data from the web which might not be in their current projection and display it.
In order to allow this, it is proposed to add reprojection support to OpenLayers via proj4js.
Projection support in OpenLayers will be implemented as an OpenLayers.Projection object -- if proj4js is not available, this Projection object (and the transform() method on it) will simply be a no-op, used only for storing limited projection information.
The OpenLayers.Projection object will be the best way to set the projection, and in 3.0, using strings for projection identifiers will be removed entirely.
Existing Tickets:
