Add support for exporting SLDs with NamedLayer.

Author: jericks

src/main/groovy/geoscript/style/io/SLDWriter.groovy

@@ -2,6 +2,7 @@ package geoscript.style.io
 
 import geoscript.style.Style
 import org.geotools.factory.CommonFactoryFinder
+import org.geotools.styling.NamedLayer
 import org.geotools.xml.styling.SLDTransformer
 import org.geotools.styling.StyleFactory
 import org.geotools.styling.StyledLayerDescriptor
@@ -27,6 +28,7 @@ class SLDWriter implements Writer {
      * Write the Style to the OutputStream
      * @param options Optional named parameters
      * <ol>
+     *     <li>type = Whether to export UserLayer (default) or NamedLayer </li>
      *     <li>exportDefaultValues = Whether to export default values or not (defaults to false) </li>
      *     <li>indentation = The number of spaces to use when indenting (defaults to 2) </li>
      * </ol>
@@ -35,10 +37,16 @@ class SLDWriter implements Writer {
      */
     void write(Map options = [:], Style style, OutputStream out) {
         StyleFactory sf = CommonFactoryFinder.getStyleFactory(null)
-        UserLayer userLayer = sf.createUserLayer()
-        userLayer.addUserStyle(style.gtStyle)
         StyledLayerDescriptor sld = sf.createStyledLayerDescriptor()
-        sld.addStyledLayer(userLayer)
+        if (options.get("type", "UserLayer").equalsIgnoreCase("UserLayer")) {
+            UserLayer userLayer = sf.createUserLayer()
+            userLayer.addUserStyle(style.gtStyle)
+            sld.addStyledLayer(userLayer)
+        } else {
+            NamedLayer namedLayer = sf.createNamedLayer()
+            namedLayer.addStyle(style.gtStyle)
+            sld.addStyledLayer(namedLayer)
+        }
         def transformer = new SLDTransformer()
         transformer.exportDefaultValues = options.get("exportDefaultValues", false)
         if (format) {

src/test/groovy/geoscript/style/io/SLDWriterTestCase.groovy

@@ -16,7 +16,7 @@ class SLDWriterTestCase {
 
     @Rule
     public TemporaryFolder folder = new TemporaryFolder()
-    
+
     private String NEW_LINE = System.getProperty("line.separator")
 
     private String expectedSld = """<?xml version="1.0" encoding="UTF-8"?><sld:StyledLayerDescriptor 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" version="1.0.0">
@@ -115,4 +115,38 @@ class SLDWriterTestCase {
 </sld:StyledLayerDescriptor>"""
         AssertUtil.assertStringsEqual expected, sld, removeXmlNS: true, trim: true
     }
+
+
+    @Test void writeNamedLayerToOutputStream() {
+        Symbolizer sym = new Fill("wheat") + new Stroke("brown")
+        SLDWriter writer = new SLDWriter();
+        ByteArrayOutputStream out = new ByteArrayOutputStream()
+        writer.write(sym, out, type: "NamedLayer")
+        String sld = out.toString().trim()
+        assertNotNull sld
+        assertTrue sld.length() > 0
+        AssertUtil.assertStringsEqual """<?xml version="1.0" encoding="UTF-8"?><sld:StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:sld="http://www.opengis.net/sld" xmlns:gml="http://www.opengis.net/gml" xmlns:ogc="http://www.opengis.net/ogc" version="1.0.0">
+  <sld:NamedLayer>
+    <sld:Name/>
+    <sld:UserStyle>
+      <sld:Name>Default Styler</sld:Name>
+      <sld:FeatureTypeStyle>
+        <sld:Name>name</sld:Name>
+        <sld:Rule>
+          <sld:PolygonSymbolizer>
+            <sld:Fill>
+              <sld:CssParameter name="fill">#f5deb3</sld:CssParameter>
+            </sld:Fill>
+          </sld:PolygonSymbolizer>
+          <sld:LineSymbolizer>
+            <sld:Stroke>
+              <sld:CssParameter name="stroke">#a52a2a</sld:CssParameter>
+            </sld:Stroke>
+          </sld:LineSymbolizer>
+        </sld:Rule>
+      </sld:FeatureTypeStyle>
+    </sld:UserStyle>
+  </sld:NamedLayer>
+</sld:StyledLayerDescriptor>""", sld, removeXmlNS: true, trim: true
+    }
 }