artemp/trac2github — Issue #181: Parameter for line symbolizer to offset line to one side
Author: artemp
Created: 2011-10-09 20:18:43+00:00
State: open
Labels: Core_Library

An additional parameter for the line symbolizer, which would allow to shift a line asymmetrically to one side is currently missing.

It would allow some visualizations currently not possible: e.g. one side of a road could be painted in a color indicating a cycle way on that side, or several hiking routes with different colors could be rendered side by side instead of one route hiding the other.

The shift should be specifiable in pixels (to be able to make it consistent with line widths etc.), and maybe alternatively in map units (to paint a second line with a known constant distance to another one).

The difference to ticket http://trac.mapnik.org/ticket/51 would be, that the line would not be a border, but could have a larger distance or could overlap a main line, there could even be no main (unshifted) line, and it would allow asymmetric shifts (to only one side instead of always on both sides).