Proposed change to symbols.

[imap at chesapeake.net]

Steve/List,

Being one of the advocates for symbol/marker changes, here is some rationale
behind the changes.  The current symbol files are somewhat static and if the
files become large, there is overhead incurred on every invocation of mapserv.
Also, the current scheme also does not lend itself to dynamic marker placement
very 
well.  (that is, using a marker NOT defined in marker.sym)

We want to be able to use external markers from a PATH filespec to make it
easier
to maintain (no more editing the marker.sym file ;) and (2) make it more
programmer
friendly and simplifies the mapscript a bit.

As far as functionality, it would be nice to interrogate a $class->{symbol} to
determine it's height/width and some sort of option to set/get control of
collision
avoidance (labelcache).  (I think needed for both POINT and ANNOTATION 
layers) And lastly, make sure to preserve the ability to examine to labelcache
to
extract the polygons of the markers and text placed on the map.

I am all for getting rid of marker.sym 100% although it may break my current
applications...  sometimes change is painful.   Anyway to code an interim
solutions that works both ways?  probably not, but thought I would ask anyway.

Regards,

Chris Stuber (mapsurfer)
Silicon Mapping Solutions, Inc.
410.257.3187


Stephen Lime wrote:
> 
> I'd like to propose a couple of changes to the way symbols are handled. This is to make symbols easier to manage and to support some additional functionality proposed by a couple of other users. The initial change would be this:
> 
> Do away with separate marker, line and shade symbol files in favor of a single symbol file. Also, allow symbol definitions in the map file.
> 
> Syntax would be the same and access (i.e. symbols referenced in class objects) would be the same. These changes allow for a simpler MapScript symbol interface and additional opportunities for defining symbols on-the-fly. Begining in 3.3.011 you can already specify a GIF/PNG file (relative to the location of the map file) in a class object (i.e. SYMBOL "graphics/marker.gif") and a symbol is dynamically created. MapScript method $map->getSymbolByName("graphics/marker.gif"); will also work.
> 
> Any thoughts or can I code it?
> 
> Steve