If no project layer order set, use layer tree layer order

for QgsMapThemeCollection::masterVisibleLayers()

python/core/layertree/qgslayertree.sip

@@ -12,11 +12,8 @@
  */
 namespace QgsLayerTree
 {
-  //! Check whether the node is a valid group node
-  bool isGroup( QgsLayerTreeNode* node );
-
-  //! Check whether the node is a valid layer node
-  bool isLayer( QgsLayerTreeNode* node );
+  bool isGroup( QgsLayerTreeNode *node );
+  bool isLayer( const QgsLayerTreeNode *node );
 
   //! Cast node to a group. No type checking is done - use isGroup() to find out whether this operation is legal.
   // PYTHON: automatic cast

python/core/layertree/qgslayertreenode.sip

@@ -70,7 +70,7 @@ class QgsLayerTreeNode : QObject
     ~QgsLayerTreeNode();
 
     //! Find out about type of the node. It is usually shorter to use convenience functions from QgsLayerTree namespace for that
-    NodeType nodeType();
+    NodeType nodeType() const;
     //! Get pointer to the parent. If parent is a null pointer, the node is a root node
     QgsLayerTreeNode *parent();
     //! Get list of children of the node. Children are owned by the parent
@@ -132,8 +132,7 @@ class QgsLayerTreeNode : QObject
     //! Return whether this node is unchecked and all its children.
     //! @note added in 3.0
     bool isItemVisibilityUncheckedRecursive() const;
-
-    //! Return whether the node should be shown as expanded or collapsed in GUI
+    QList< QgsMapLayer * > checkedLayers() const;
     bool isExpanded() const;
     //! Set whether the node should be shown as expanded or collapsed in GUI
     void setExpanded( bool expanded );

src/core/layertree/qgslayertree.h

@@ -37,7 +37,7 @@ namespace QgsLayerTree
   }
 
   //! Check whether the node is a valid layer node
-  inline bool isLayer( QgsLayerTreeNode *node )
+  inline bool isLayer( const QgsLayerTreeNode *node )
   {
     return node && node->nodeType() == QgsLayerTreeNode::NodeLayer;
   }
@@ -54,6 +54,12 @@ namespace QgsLayerTree
     return static_cast<QgsLayerTreeLayer *>( node );
   }
 
+  //! Cast node to a layer. No type checking is done - use isLayer() to find out whether this operation is legal.
+  inline const QgsLayerTreeLayer *toLayer( const QgsLayerTreeNode *node )
+  {
+    return static_cast< const QgsLayerTreeLayer *>( node );
+  }
+
 }
 
 #endif // QGSLAYERTREE_H

src/core/layertree/qgslayertreenode.cpp

@@ -126,6 +126,26 @@ bool QgsLayerTreeNode::isItemVisibilityUncheckedRecursive() const
   return true;
 }
 
+void fetchCheckedLayers( const QgsLayerTreeNode *node, QList<QgsMapLayer *> &layers )
+{
+  if ( QgsLayerTree::isLayer( node ) )
+  {
+    const QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( node );
+    if ( nodeLayer->isVisible() )
+      layers << nodeLayer->layer();
+  }
+
+  Q_FOREACH ( QgsLayerTreeNode *child, node->children() )
+    fetchCheckedLayers( child, layers );
+}
+
+QList<QgsMapLayer *> QgsLayerTreeNode::checkedLayers() const
+{
+  QList<QgsMapLayer *> layers;
+  fetchCheckedLayers( this, layers );
+  return layers;
+}
+
 void QgsLayerTreeNode::setExpanded( bool expanded )
 {
   if ( mExpanded == expanded )

src/core/layertree/qgslayertreenode.h

@@ -24,6 +24,7 @@
 class QDomElement;
 
 class QgsProject;
+class QgsMapLayer;
 
 /** \ingroup core
  * This class is a base class for nodes in a layer tree.
@@ -80,7 +81,7 @@ class CORE_EXPORT QgsLayerTreeNode : public QObject
     ~QgsLayerTreeNode();
 
     //! Find out about type of the node. It is usually shorter to use convenience functions from QgsLayerTree namespace for that
-    NodeType nodeType() { return mNodeType; }
+    NodeType nodeType() const { return mNodeType; }
     //! Get pointer to the parent. If parent is a null pointer, the node is a root node
     QgsLayerTreeNode *parent() { return mParent; }
     //! Get list of children of the node. Children are owned by the parent
@@ -145,6 +146,13 @@ class CORE_EXPORT QgsLayerTreeNode : public QObject
     //! @note added in 3.0
     bool isItemVisibilityUncheckedRecursive() const;
 
+    /**
+     * Returns a list of any checked layers which belong to this node or its
+     * children.
+     * @note added in QGIS 3.0
+     */
+    QList< QgsMapLayer * > checkedLayers() const;
+
     //! Return whether the node should be shown as expanded or collapsed in GUI
     bool isExpanded() const;
     //! Set whether the node should be shown as expanded or collapsed in GUI

src/core/qgsmapthemecollection.cpp

@@ -185,17 +185,25 @@ QList<QgsMapLayer *> QgsMapThemeCollection::masterLayerOrder() const
 
 QList<QgsMapLayer *> QgsMapThemeCollection::masterVisibleLayers() const
 {
-  QList< QgsMapLayer * > visible;
-  Q_FOREACH ( QgsMapLayer *layer, masterLayerOrder() )
+  QList< QgsMapLayer *> allLayers = masterLayerOrder();
+  QList< QgsMapLayer * > visibleLayers = mProject->layerTreeRoot()->checkedLayers();
+
+  if ( allLayers.isEmpty() )
   {
-    QgsLayerTreeLayer *nodeLayer = mProject->layerTreeRoot()->findLayer( layer );
-    if ( nodeLayer )
-    {
-      if ( nodeLayer->isVisible() )
-        visible << layer;
-    }
+    // no project layer order set
+    return visibleLayers;
+  }
+
+  else
+  {
+    QList< QgsMapLayer * > orderedVisibleLayers;
+    Q_FOREACH ( QgsMapLayer *layer, allLayers )
+    {
+      if ( visibleLayers.contains( layer ) )
+        orderedVisibleLayers << layer;
+    }
+    return orderedVisibleLayers;
   }
-  return visible;
 }
 
 

tests/src/python/test_qgsmapthemecollection.py

@@ -204,6 +204,11 @@ class TestQgsMapThemeCollection(unittest.TestCase):
         prj.setLayerOrder([layer, layer2, layer3])
         self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer, layer3])
 
+        # test with no project layer order set, should respect tree order
+        prj.setLayerOrder([])
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer, layer3])
+        layer_node.setItemVisibilityChecked(True)
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer, layer2, layer3])
 
 if __name__ == '__main__':
     unittest.main()