Add support for reading SLD's with multiple FeatureTypeStyle elements.

Roel · m-kuhn · commit c49a18c587b6 · 2018-05-31T10:51:32.000+02:00
Introduce a virtual FeatureTypeStyle to add support for reading SLD documents with more than one FeatureTypeStyle element. Still supports SLD's with one FeatureTypeStyle, as well as SLD's with multiple FeatureTypeStyles, including empty FeatureTypeStyles (not breaking single symbol rendering in that case). Complies with SLD's painter's model for rendering, appending Rules from subsequent FeatureTypeStyles in order. Fix #6413 (http://hub.qgis.org/issues/6413)
diff --git a/src/core/symbology/qgsrenderer.cpp b/src/core/symbology/qgsrenderer.cpp
@@ -223,47 +223,51 @@ QgsFeatureRenderer *QgsFeatureRenderer::loadSld( const QDomNode &node, QgsWkbTyp
     return nullptr;
   }
 
+  // create empty FeatureTypeStyle element to merge Rule's from all FeatureTypeStyle's
+  QDomElement mergedFeatTypeStyle = featTypeStyleElem.cloneNode( false ).toElement();
+
   // use the RuleRenderer when more rules are present or the rule
   // has filters or min/max scale denominators set,
   // otherwise use the SingleSymbol renderer
   bool needRuleRenderer = false;
   int ruleCount = 0;
 
-  QDomElement ruleElem = featTypeStyleElem.firstChildElement( QStringLiteral( "Rule" ) );
-  while ( !ruleElem.isNull() )
+  while ( !featTypeStyleElem.isNull() )
   {
-    ruleCount++;
-
-    // more rules present, use the RuleRenderer
-    if ( ruleCount > 1 )
+    QDomElement ruleElem = featTypeStyleElem.firstChildElement( QStringLiteral( "Rule" ) );
+    while ( !ruleElem.isNull() )
     {
-      QgsDebugMsg( "more Rule elements found: need a RuleRenderer" );
-      needRuleRenderer = true;
-      break;
-    }
+      ruleCount++;
 
-    QDomElement ruleChildElem = ruleElem.firstChildElement();
-    while ( !ruleChildElem.isNull() )
-    {
-      // rule has filter or min/max scale denominator, use the RuleRenderer
-      if ( ruleChildElem.localName() == QLatin1String( "Filter" ) ||
-           ruleChildElem.localName() == QLatin1String( "MinScaleDenominator" ) ||
-           ruleChildElem.localName() == QLatin1String( "MaxScaleDenominator" ) )
+      // append a clone of all Rules to the merged FeatureTypeStyle element
+      mergedFeatTypeStyle.appendChild( ruleElem.cloneNode().toElement() );
+      // more rules present, use the RuleRenderer
+
+      if ( ruleCount > 1 )
       {
-        QgsDebugMsg( "Filter or Min/MaxScaleDenominator element found: need a RuleRenderer" );
+        QgsDebugMsg( "more Rule elements found: need a RuleRenderer" );
         needRuleRenderer = true;
-        break;
       }
 
-      ruleChildElem = ruleChildElem.nextSiblingElement();
-    }
+      QDomElement ruleChildElem = ruleElem.firstChildElement();
+      while ( !ruleChildElem.isNull() )
+      {
+        // rule has filter or min/max scale denominator, use the RuleRenderer
+        if ( ruleChildElem.localName() == QLatin1String( "Filter" ) ||
+             ruleChildElem.localName() == QLatin1String( "MinScaleDenominator" ) ||
+             ruleChildElem.localName() == QLatin1String( "MaxScaleDenominator" ) )
+        {
+          QgsDebugMsg( "Filter or Min/MaxScaleDenominator element found: need a RuleRenderer" );
+          needRuleRenderer = true;
+          break;
+        }
+
+        ruleChildElem = ruleChildElem.nextSiblingElement();
+      }
 
-    if ( needRuleRenderer )
-    {
-      break;
+      ruleElem = ruleElem.nextSiblingElement( QStringLiteral( "Rule" ) );
     }
-
-    ruleElem = ruleElem.nextSiblingElement( QStringLiteral( "Rule" ) );
+    featTypeStyleElem = featTypeStyleElem.nextSiblingElement( QStringLiteral( "FeatureTypeStyle" ) );
   }
 
   QString rendererType;
@@ -285,7 +289,7 @@ QgsFeatureRenderer *QgsFeatureRenderer::loadSld( const QDomNode &node, QgsWkbTyp
     return nullptr;
   }
 
-  QgsFeatureRenderer *r = m->createRendererFromSld( featTypeStyleElem, geomType );
+  QgsFeatureRenderer *r = m->createRendererFromSld( mergedFeatTypeStyle, geomType );
   return r;
 }
 
