Add method for retrieving legend nodes by layer ID and legend rule key

python/core/layertree/qgslayertreemodel.sip

@@ -97,6 +97,15 @@ class QgsLayerTreeModel : QAbstractItemModel
     //! @note added in 2.6
     QList<QgsLayerTreeModelLegendNode*> layerLegendNodes( QgsLayerTreeLayer* nodeLayer );
 
+    /** Searches through the layer tree to find a legend node with a matching layer ID
+     * and rule key.
+     * @param layerId map layer ID
+     * @param ruleKey legend node rule key
+     * @returns QgsLayerTreeModelLegendNode if found
+     * @note added in QGIS 2.14
+     */
+    QgsLayerTreeModelLegendNode* findLegendNode( const QString& layerId, const QString& ruleKey ) const;
+
     //! Return pointer to the root node of the layer tree. Always a non-null pointer.
     QgsLayerTreeGroup* rootGroup() const;
     //! Reset the model and use a new root group node

src/core/layertree/qgslayertreemodel.cpp

@@ -1333,6 +1333,26 @@ QList<QgsLayerTreeModelLegendNode*> QgsLayerTreeModel::layerLegendNodes( QgsLaye
   return mLegend.value( nodeLayer ).activeNodes;
 }
 
+QgsLayerTreeModelLegendNode* QgsLayerTreeModel::findLegendNode( const QString& layerId, const QString& ruleKey ) const
+{
+  Q_FOREACH ( QgsLayerTreeLayer* layer, mLegend.keys() )
+  {
+    if ( layer->layerId() == layerId )
+    {
+      Q_FOREACH ( QgsLayerTreeModelLegendNode* legendNode, mLegend.value( layer ).activeNodes )
+      {
+        if ( legendNode->data( QgsLayerTreeModelLegendNode::RuleKeyRole ).toString() == ruleKey )
+        {
+          //found it!
+          return legendNode;
+        }
+      }
+    }
+  }
+
+  return 0;
+}
+
 void QgsLayerTreeModel::legendInvalidateMapBasedData()
 {
   if ( !testFlag( DeferredLegendInvalidation ) )

src/core/layertree/qgslayertreemodel.h

@@ -121,6 +121,15 @@ class CORE_EXPORT QgsLayerTreeModel : public QAbstractItemModel
     //! @note added in 2.6
     QList<QgsLayerTreeModelLegendNode*> layerLegendNodes( QgsLayerTreeLayer* nodeLayer );
 
+    /** Searches through the layer tree to find a legend node with a matching layer ID
+     * and rule key.
+     * @param layerId map layer ID
+     * @param ruleKey legend node rule key
+     * @returns QgsLayerTreeModelLegendNode if found
+     * @note added in QGIS 2.14
+     */
+    QgsLayerTreeModelLegendNode* findLegendNode( const QString& layerId, const QString& ruleKey ) const;
+
     //! Return pointer to the root node of the layer tree. Always a non-null pointer.
     QgsLayerTreeGroup* rootGroup() const;
     //! Reset the model and use a new root group node

tests/src/core/testqgslayertree.cpp

@@ -38,6 +38,7 @@ class TestQgsLayerTree : public QObject
     void testCheckStateMutuallyExclusive();
     void testCheckStateMutuallyExclusiveEdgeCases();
     void testShowHideAllSymbolNodes();
+    void testFindLegendNode();
 
   private:
 
@@ -268,6 +269,48 @@ void TestQgsLayerTree::testShowHideAllSymbolNodes()
   QgsMapLayerRegistry::instance()->removeMapLayers( QList<QgsMapLayer*>() << vl );
 }
 
+void TestQgsLayerTree::testFindLegendNode()
+{
+  //new memory layer
+  QgsVectorLayer* vl = new QgsVectorLayer( "Point?field=col1:integer", "vl", "memory" );
+  QVERIFY( vl->isValid() );
+
+  QgsMapLayerRegistry::instance()->addMapLayers( QList<QgsMapLayer*>() << vl );
+
+  //create a categorized renderer for layer
+  QgsCategorizedSymbolRendererV2* renderer = new QgsCategorizedSymbolRendererV2();
+  renderer->setClassAttribute( "col1" );
+  renderer->setSourceSymbol( QgsSymbolV2::defaultSymbol( QGis::Point ) );
+  renderer->addCategory( QgsRendererCategoryV2( "a", QgsSymbolV2::defaultSymbol( QGis::Point ), "a" ) );
+  renderer->addCategory( QgsRendererCategoryV2( "b", QgsSymbolV2::defaultSymbol( QGis::Point ), "b" ) );
+  renderer->addCategory( QgsRendererCategoryV2( "c", QgsSymbolV2::defaultSymbol( QGis::Point ), "c" ) );
+  vl->setRendererV2( renderer );
+
+  //create legend with symbology nodes for categorized renderer
+  QgsLayerTreeGroup* root = new QgsLayerTreeGroup();
+  QgsLayerTreeModel* m = new QgsLayerTreeModel( root, 0 );
+  QVERIFY( !m->findLegendNode( QString( "id" ), QString( "rule" ) ) );
+  QgsLayerTreeLayer* n = new QgsLayerTreeLayer( vl );
+  root->addChildNode( n );
+  m->refreshLayerLegend( n );
+  QVERIFY( !m->findLegendNode( QString( "id" ), QString( "rule" ) ) );
+  QVERIFY( !m->findLegendNode( QString( "vl" ), QString( "rule" ) ) );
+
+  QgsLegendSymbolListV2 symbolList = renderer->legendSymbolItemsV2();
+  Q_FOREACH ( const QgsLegendSymbolItemV2& symbol, symbolList )
+  {
+    QgsLayerTreeModelLegendNode* found = m->findLegendNode( vl->id(), symbol.ruleKey() );
+    QVERIFY( found );
+    QCOMPARE( found->layerNode()->layerId(), vl->id() );
+    QCOMPARE( found->data( Qt::DisplayRole ).toString(), symbol.label() );
+  }
+
+  //cleanup
+  delete m;
+  delete root;
+  QgsMapLayerRegistry::instance()->removeMapLayers( QList<QgsMapLayer*>() << vl );
+}
+
 
 QTEST_MAIN( TestQgsLayerTree )
 #include "testqgslayertree.moc"