Letterspacing is different for polyline labels

[olt]

Labels on a straight line are rendered differently than on curved lines. As mentioned in #4026, the inter-character spacing is defined in the font itself, but that spacing is multiplied by 1.25 when a label is rendered on a polyline.
See: https://github.com/mapserver/mapserver/blob/master/mapprimitive.c#L1818

Here you can see how "Alter Wall" and "Neuer Wall" are rendered with different spacing. "Alter Wall" is on a straight line, while "Neuer Wall" is on a curved line.
https://dl.dropbox.com/u/2633201/issues/mapserver/letterspacing-125.png

Changing the letterspacing to 1.0 in mapprimitice.c make the rendering more similar:
https://dl.dropbox.com/u/2633201/issues/mapserver/letterspacing-100.png

[tbonfort]

I would be in favor of removing the 1.25 letterspacing factor as it doesn't prevent overlapping artifacts, and produces incoherent results across different features (some FOLLOW labels fall back to AUTO, in which case they are rendered without the spacing applied). Do you want to bring this up on the mailing list ?

[olt]

I did: http://lists.osgeo.org/pipermail/mapserver-dev/2012-July/012472.html