Layers¶

An SLD document contains a sequence of layer definitions indicating the layers to be styled. Each layer definition is either a NamedLayer reference or a supplied UserLayer.

NamedLayer¶

A NamedLayer specifies an existing layer to be styled, and the styling to apply to it. The styling may be any combination of catalog styles and explicitly-defined styles. If no style is specified, the default style for the layer is used.

The <NamedLayer> element contains the following elements:

Tag	Required?	Description
`<Name>`	Yes	The name of the layer to be styled. (Ignored in catalog styles.)
`<Description>`	No	The description for the layer.
`<NamedStyle>`	0..N	The name of a catalog style to apply to the layer.
`<UserStyle>`	0..N	The definition of a style to apply to the layer. See Styles

UserLayer¶

A UserLayer defines a new layer to be styled, and the styling to apply to it. The data for the layer is provided directly in the layer definition using the <InlineFeature> element. Since the layer is not known to the server, the styling must be explicitly specified as well.

The <UserLayer> element contains the following elements:

Tag	Required?	Description
`<Name>`	No	The name for the layer being defined
`<Description>`	No	The description for the layer
`<InlineFeature>`	No	One or more feature collections providing the layer data, specified using GML.
`<UserStyle>`	1..N	The definition of the style(s) to use for the layer. See Styles

A common use is to define a geometry to be rendered to indicate an Area Of Interest.

InlineFeature¶

An InlineFeature element contains data defining a layer to be styled. The element contains one or more <FeatureCollection> elements defining the data. Each Feature Collection can contain any number of <featureMember> elements, each containing a feature specified using GML markup. The features can contain any type of geometry (point, line or polygon, and collections of these). They may also contain scalar-valued attributes, which can be useful for labelling.

Example¶

The following style specifies a named layer using the default style, and a user-defined layer with inline data and styling. It displays the US States layer, with a labelled red box surrounding the Pacific NW.

<sld:StyledLayerDescriptor xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd"
   xmlns:sld="http://www.opengis.net/sld" version="1.0.0">
   <sld:NamedLayer>
      <sld:Name>usa:states</sld:Name>
   </sld:NamedLayer>
   <sld:UserLayer>
      <sld:Name>Inline</sld:Name>
      <sld:InlineFeature>
         <sld:FeatureCollection>
            <sld:featureMember>
              <feature>
                <geometryProperty>
                  <gml:Polygon>
                     <gml:outerBoundaryIs>
                        <gml:LinearRing>
                           <gml:coordinates>
           -127.0,51.0 -110.0,51.0 -110.0,41.0 -127.0,41.0 -127.0,51.0
                           </gml:coordinates>
                        </gml:LinearRing>
                     </gml:outerBoundaryIs>
                  </gml:Polygon>
                </geometryProperty>
                <title>Pacific NW </title>
              </feature>
            </sld:featureMember>
         </sld:FeatureCollection>
      </sld:InlineFeature>
      <sld:UserStyle>
         <sld:FeatureTypeStyle>
            <sld:Rule>
                  <sld:PolygonSymbolizer>
                <Stroke>
                  <CssParameter name="stroke">#FF0000</CssParameter>
                  <CssParameter name="stroke-width">2</CssParameter>
                </Stroke>
              </sld:PolygonSymbolizer>
              <sld:TextSymbolizer>
                <sld:Label>
                  <ogc:PropertyName>title</ogc:PropertyName>
                </sld:Label>
                <sld:Fill>
                  <sld:CssParameter name="fill">#FF0000</sld:CssParameter>
                </sld:Fill>
              </sld:TextSymbolizer>
            </sld:Rule>
         </sld:FeatureTypeStyle>
      </sld:UserStyle>
   </sld:UserLayer>
</sld:StyledLayerDescriptor>