Move recursive "collect layers" algorithm to QgsLayerTreeUtils + tests

python/core/auto_generated/layertree/qgslayertreeutils.sip.in

@@ -96,6 +96,14 @@ Insert a QgsMapLayer just below another one
 :param layerToInsert: the new layer to insert just below the reference layer
 
 :return: the new tree layer
+%End
+
+    static QSet<QgsMapLayer *> collectMapLayersRecursive( const QList<QgsLayerTreeNode *> &nodes );
+%Docstring
+Returns map layers from the given list of layer tree nodes. Also recursively visits
+child nodes of groups.
+
+.. versionadded:: 3.4
 %End
 };
 

src/core/layertree/qgslayertreeutils.cpp

@@ -413,3 +413,27 @@ QgsLayerTreeLayer *QgsLayerTreeUtils::insertLayerBelow( QgsLayerTreeGroup *group
   QgsLayerTreeGroup *parent = static_cast<QgsLayerTreeGroup *>( inTree->parent() ) ? static_cast<QgsLayerTreeGroup *>( inTree->parent() ) : group;
   return parent->insertLayer( idx, layerToInsert );
 }
+
+static void _collectMapLayers( const QList<QgsLayerTreeNode *> &nodes, QSet<QgsMapLayer *> &layersSet )
+{
+  for ( QgsLayerTreeNode *node : nodes )
+  {
+    if ( QgsLayerTree::isLayer( node ) )
+    {
+      QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( node );
+      if ( nodeLayer->layer() )
+        layersSet << nodeLayer->layer();
+    }
+    else if ( QgsLayerTree::isGroup( node ) )
+    {
+      _collectMapLayers( QgsLayerTree::toGroup( node )->children(), layersSet );
+    }
+  }
+}
+
+QSet<QgsMapLayer *> QgsLayerTreeUtils::collectMapLayersRecursive( const QList<QgsLayerTreeNode *> &nodes )
+{
+  QSet<QgsMapLayer *> layersSet;
+  _collectMapLayers( nodes, layersSet );
+  return layersSet;
+}

src/core/layertree/qgslayertreeutils.h

@@ -87,6 +87,13 @@ class CORE_EXPORT QgsLayerTreeUtils
      * \returns the new tree layer
      */
     static QgsLayerTreeLayer *insertLayerBelow( QgsLayerTreeGroup *group, const QgsMapLayer *refLayer, QgsMapLayer *layerToInsert );
+
+    /**
+     * Returns map layers from the given list of layer tree nodes. Also recursively visits
+     * child nodes of groups.
+     * \since QGIS 3.4
+     */
+    static QSet<QgsMapLayer *> collectMapLayersRecursive( const QList<QgsLayerTreeNode *> &nodes );
 };
 
 #endif // QGSLAYERTREEUTILS_H

src/gui/layertree/qgslayertreeview.cpp

@@ -19,6 +19,7 @@
 #include "qgslayertreeembeddedwidgetregistry.h"
 #include "qgslayertreemodel.h"
 #include "qgslayertreemodellegendnode.h"
+#include "qgslayertreeutils.h"
 #include "qgslayertreeviewdefaultactions.h"
 #include "qgsmaplayer.h"
 #include "qgsgui.h"
@@ -356,28 +357,10 @@ QList<QgsMapLayer *> QgsLayerTreeView::selectedLayers() const
   return list;
 }
 
-static void _collectMapLayers( const QList<QgsLayerTreeNode *> &nodes, QSet<QgsMapLayer *> &layersSet )
-{
-  for ( QgsLayerTreeNode *node : nodes )
-  {
-    if ( QgsLayerTree::isLayer( node ) )
-    {
-      QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( node );
-      if ( nodeLayer->layer() )
-        layersSet << nodeLayer->layer();
-    }
-    else if ( QgsLayerTree::isGroup( node ) )
-    {
-      _collectMapLayers( QgsLayerTree::toGroup( node )->children(), layersSet );
-    }
-  }
-}
-
 QList<QgsMapLayer *> QgsLayerTreeView::selectedLayersRecursive() const
 {
-  QSet<QgsMapLayer *> layersSet;
   const QList<QgsLayerTreeNode *> nodes = layerTreeModel()->indexes2nodes( selectionModel()->selectedIndexes(), false );
-  _collectMapLayers( nodes, layersSet );
+  QSet<QgsMapLayer *> layersSet = QgsLayerTreeUtils::collectMapLayersRecursive( nodes );
   return layersSet.toList();
 }
 

tests/src/core/testqgslayertree.cpp

@@ -26,6 +26,7 @@
 #include <qgsrulebasedrenderer.h>
 #include <qgslayertreemodel.h>
 #include <qgslayertreemodellegendnode.h>
+#include <qgslayertreeutils.h>
 
 class TestQgsLayerTree : public QObject
 {
@@ -50,6 +51,7 @@ class TestQgsLayerTree : public QObject
     void testFindLayer();
     void testLayerDeleted();
     void testFindGroups();
+    void testUtilsCollectMapLayers();
 
   private:
 
@@ -661,6 +663,30 @@ void TestQgsLayerTree::testFindGroups()
   QVERIFY( groups.contains( group3 ) );
 }
 
+void TestQgsLayerTree::testUtilsCollectMapLayers()
+{
+  QgsVectorLayer *vl1 = new QgsVectorLayer( QStringLiteral( "Point?field=col1:integer" ), QStringLiteral( "vl1" ), QStringLiteral( "memory" ) );
+  QgsVectorLayer *vl2 = new QgsVectorLayer( QStringLiteral( "Point?field=col1:integer" ), QStringLiteral( "vl1" ), QStringLiteral( "memory" ) );
+
+  QgsProject project;
+  project.addMapLayer( vl1 );
+  project.addMapLayer( vl2 );
+
+  QgsLayerTree root;
+  QgsLayerTreeLayer *nodeVl1 = root.addLayer( vl1 );
+  QgsLayerTreeGroup *nodeGrp = root.addGroup( "grp" );
+  QgsLayerTreeLayer *nodeVl2 = nodeGrp->addLayer( vl2 );
+  Q_UNUSED( nodeVl2 );
+
+  QSet<QgsMapLayer *> set1 = QgsLayerTreeUtils::collectMapLayersRecursive( QList<QgsLayerTreeNode *>() << &root );
+  QSet<QgsMapLayer *> set2 = QgsLayerTreeUtils::collectMapLayersRecursive( QList<QgsLayerTreeNode *>() << nodeVl1 );
+  QSet<QgsMapLayer *> set3 = QgsLayerTreeUtils::collectMapLayersRecursive( QList<QgsLayerTreeNode *>() << nodeGrp );
+
+  QCOMPARE( set1, QSet<QgsMapLayer *>() << vl1 << vl2 );
+  QCOMPARE( set2, QSet<QgsMapLayer *>() << vl1 );
+  QCOMPARE( set3, QSet<QgsMapLayer *>() << vl2 );
+}
+
 
 QGSTEST_MAIN( TestQgsLayerTree )
 #include "testqgslayertree.moc"