Changing symbol icon on the fly

[Sean Gillies]

On Apr 27, 2005, at 9:32 AM, Aaron Craig wrote:

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>
> Using mapscript (perl, but any generic example will do) what's the
> preferred way to change the icon of a point, in a layer that is defined
> as follows:
>
> LAYER
> ~  NAME "musei"
> ~  TYPE POINT
> ~  STATUS OFF
>
> ~  CONNECTION 'user=tsc2 password=tsc2 dbname=geo_sardegna'
> ~  CONNECTIONTYPE POSTGIS
> ~  DATA 'the_point from musei'
>
> ~  CLASS
> ~    NAME "musei"
> ~    STYLE
> ~    SYMBOL
> "/var/www/OpenPortal/htdocs/confartigianato/Images/icona_small.gif"
> ~    SIZE  10
> ~    COLOR 0 0 0
> ~  END
> END
>
>
> I'm doing
>
> my $lyrPoints = $map->getLayerByName($sLayerName);
>
> $lyrPoints->{status} = $mapscript::MS_ON;
> my $cls = $lyrPoints->getClass(0); # change this if we ever use layers
> with more than one class
> my $stl = $cls->getStyle(0); # change this if we ever use classes with
> more than one style
> my $nSymbolIndex = $stl->{symbol};
>
> my $sym = $map->{symbolset}->getSymbol($nSymbolIndex);
> $sym->{imagepath} =
> "/var/www/OpenPortal/htdocs/confartigianato/Images/$sLayerName.gif";
>
> [snip]

Aaron,

Symbols are more static than dynamic.  You can't mutate their imagepath
like that.  You can, however modify your map's symbolset so that it
contains custom symbols:

   # create and add a new symbol
   layer_name = 'foo'
   symbol_path = '/path/to/foo/symbol.gif'
   new_symbol = mapscript.symbolObj(layer_name, symbol_path)
   new_index = map.symbolset.appendSymbol(new_symbol)

   # assign this new symbol to the styleObj
   style.symbol = new_index

Check out these URLs for more details on symbols and symbolsets

   http://zcologia.com/mapserver/mapscript#symbolsetobj
   http://zcologia.com/mapserver/mapscript#symbolobj

cheers,
Sean

--
Sean Gillies
sgillies at frii dot com
http://users.frii.com/sgillies