[Geoserver-users] Custom function in SLD

Keane_Tim · February 8, 2014, 7:22pm

I am attempting to determine the size of a point symbol based on scale using a custom function. However, the first test of scale (if scale >= 500000:) always evaluates to true. I have chosen the scales for the script based on the fact that my base layer in an OL3 app is an OpenLayers.Layer.ArcGISCache with the following config http://maps.nyc.gov/gis/data/tiles/conf.xml

FUNCTION (iconSize.py):

def run(value, args):
       scale = args[0]
       if scale >= 500000:
             return 20
       elif scale >= 350000:
             return 22
       elif scale >= 256000:
             return 24
       elif scale >= 128000:
             return 26
       elif scale >= 64000:
             return 28
       elif scale >= 32000:
             return 30
       elif scale >= 16000:
             return 32
       elif scale >= 8000:
             return 34
       elif scale >= 4000:
             return 36
       elif scale >= 2000:
             return 38
       else:
             return 40

SLD:

<?xml version="1.0" encoding="UTF-8"?>
<sld:UserStyle xmlns="http://www.opengis.net/sld"
       xmlns:sld="http://www.opengis.net/sld"
       xmlns:ogc="http://www.opengis.net/ogc"
       xmlns:gml="http://www.opengis.net/gml">
       <sld:Name>Default Styler</sld:Name>
       <sld:FeatureTypeStyle>
             <sld:Name>name</sld:Name>
             <sld:Rule>
                    <sld:PointSymbolizer>
                           <sld:Graphic>
                                 <sld:ExternalGraphic>
                                        <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple"
                                               xlink:href="http://localhost:82/geoserver/styles/mapIcons/Recovery.svg"/>
                                        <sld:Format>image/svg+xml</sld:Format>
                                 </sld:ExternalGraphic>
                                 <sld:Size>
                                        <ogc:Function name="iconSize">
                                               <ogc:Function name="env">
                                                      <ogc:Literal>wms_scale_denominator</ogc:Literal>
                                               </ogc:Function>
                                        </ogc:Function>
                                 </sld:Size>
                           </sld:Graphic>
                    </sld:PointSymbolizer>
             </sld:Rule>
       </sld:FeatureTypeStyle>
</sld:UserStyle>

Keane_Tim · February 9, 2014, 5:56am

Thanks, I’ll checkout recode. I have no idea what value I am getting for wms_scale_denominator… I even made the first test in the script scale >= 10000000 and it still returned true.

···

The recode function can be used for switch statement like logic. So no need to write a custom function.

I wonder what value you are getting for wms_scale_denominator ?

Jody Garnett

On Sun, Feb 9, 2014 at 6:22 AM, Keane, Tim <tkeane@anonymised.com> wrote:

I am attempting to determine the size of a point symbol based on scale using a custom function. However, the first test of scale (if scale >= 500000:) always evaluates to true. I have chosen the scales for the script based on the fact that my base layer in an OL3 app is an OpenLayers.Layer.ArcGISCache with the following config http://maps.nyc.gov/gis/data/tiles/conf.xml

FUNCTION (iconSize.py):

def run(value, args):

scale = args[0]

if scale >= 500000:

return 20

elif scale >= 350000:

return 22

elif scale >= 256000:

return 24

elif scale >= 128000:

return 26

elif scale >= 64000:

return 28

elif scale >= 32000:

return 30

elif scale >= 16000:

return 32

elif scale >= 8000:

return 34

elif scale >= 4000:

return 36

elif scale >= 2000:

return 38

else:

return 40

SLD:

<?xml version="1.0" encoding="UTF-8"?>

<sld:UserStyle xmlns=“http://www.opengis.net/sld”

xmlns:sld=“http://www.opengis.net/sld”

xmlns:ogc=“http://www.opengis.net/ogc”

xmlns:gml=“http://www.opengis.net/gml”>

sld:NameDefault Styler</sld:Name>

sld:FeatureTypeStyle

sld:Namename</sld:Name>

<sld:OnlineResource xmlns:xlink=“http://www.w3.org/1999/xlink” xlink:type=“simple”

xlink:href=“http://localhost:82/geoserver/styles/mapIcons/Recovery.svg”/>

sld:Formatimage/svg+xml</sld:Format>

</sld:ExternalGraphic>

sld:Size

<ogc:Function name=“iconSize”>

<ogc:Function name=“env”>

ogc:Literalwms_scale_denominator</ogc:Literal>

</ogc:Function>

</sld:Size>

</sld:Graphic>

</sld:PointSymbolizer>

</sld:Rule>

</sld:FeatureTypeStyle>

</sld:UserStyle>

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Andrea_Aime4 · February 9, 2014, 7:45am

On Sun, Feb 9, 2014 at 6:56 AM, Keane, Tim <tkeane@anonymised.com> wrote:

The recode function can be used for switch statement like logic. So no
need to write a custom function.

I wonder what value you are getting for wms_scale_denominator ?

Some time ago Martin Davis needed to know some of the wms related
information in his rendering
transformations, as input parameters (for heat map I think?) so I added
this:

https://github.com/geoserver/geoserver/blob/master/src/wms/src/main/java/org/geoserver/wms/RenderingVariables.java

It is called before running the code behind GetMap and GetFeatureInfo.

Cheers
Andrea

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Andrea_Aime4 · February 9, 2014, 7:54am

On Sun, Feb 9, 2014 at 6:56 AM, Keane, Tim <tkeane@anonymised.com> wrote:

Thanks, I'll checkout recode. I have no idea what value I am getting
for wms_scale_denominator... I even made the first test in the script scale
>= 10000000 and it still returned true.

To see what value you're getting, you can either log it from your function,
or use it as a label point a point:

<ogc:Literal>wms_scale_denominator</ogc:Literal>
</ogc:Function>
</Label>

Btw, for a case like this one a even simpler solution to make the icon grow
as the zoom increases
is to specificy its size in meters/feet:
http://docs.geoserver.org/latest/en/user/styling/sld-extensions/uom.html