[OGR] Problem with STYLEITEM AUTO and reprojection of units

[dmorissette]

Frank Warmerdam wrote:
> 
> However, now that I think about this, I am concerned that if PROJ is used to
> transform the spmap data from kilometers to meters the text height (expressed
> in km) will not be properly rescaled to go along with it.  If so, I doubt
> your mapfile will work properly even yet.  I will have to talk to Daniel about
> how to handle this.  I am not sure what can be done practically.
>

[dmorissette]

This could probably be handled in msOGRLayerGetAutoStyle()... in this
function we have access to the mapObj and the layerObj so we have access
to their projectionObj.  Assuming that we can ask PROJ for a units
conversion factor between the source and destination projection (when
they differ) then we could include the conversion factor in the value
passed to poStylePart->SetUnit() around line 1475.

I guess the next question is whether there is a call in PROJ to return a
units conversion factor between 2 projections?  I wonder if the PROJ
maintainer would know?  ;)