[mapserver-users] MapServer Symbol Conversion from Polyline Points

[Havard Tveite]

Precise symbol placement is among the issues that are being
addressed in RFC45 (Symbology, Labeling, and Cartography
Improvements)
<URL: http://mapserver.osgeo.org/development/rfc/ms-rfc-45.html>

In RFC45, a new tag called CENTER or ORIGIN is proposed. ANCHORPOINT
is perhaps a better name for it.  This tag could be useful to have
available both with the SYMBOL and with the STYLE.

Cite from RFC45:
CENTER/ORIGIN [x y]
Defines the centre of the symbol using decimal pixels (x axis
increasing to the right, y axis increasing downwards).
* Is used for placing a point symbol on the map or on a “decorated” line
* Defines the centre of rotation if an ANGLE is specified for point symbols.
* Default value is the centre of the symbol’s bounding box.
* Applies to TYPE ellipse, vector, pixmap, truetype.


Håvard Tveite


Bob Basques wrote:
> All,
> 
> I would vote for both the 0,0 anchoring by default and the use of the ANCHORPOINT function.   These things gave me no end of problems when I first started out with MapServer.  Took a while to figure out how to anchor oddly shaped symbols for example.
> 
> bobb
> 
> 
> 
>> As a side issue, do the positive/negative numbers have a bearing on the
>> anchor point of the symbol or is that always in the centre of the symbol?
> as of now, the symbol is centered on the anchor point. I'd be in favor
> of having a way to specify the anchor point, either by fixing it on
> 0,0 , or by specifying it alongside the symbol, eg ANCHORPOINT 0.3 2
> 
> regards,
> thomas