Add method to QgsMapThemeCollection to retrieve ordered list of

visible layers for the project

python/core/qgsmapthemecollection.sip

@@ -117,6 +117,7 @@ class QgsMapThemeCollection : QObject
     QgsProject *project();
     void setProject( QgsProject *project );
     QList< QgsMapLayer * > masterLayerOrder() const;
+    QList< QgsMapLayer * > masterVisibleLayers() const;
 
   signals:
 

src/core/qgsmapthemecollection.cpp

@@ -183,6 +183,21 @@ QList<QgsMapLayer *> QgsMapThemeCollection::masterLayerOrder() const
   return mProject->layerOrder();
 }
 
+QList<QgsMapLayer *> QgsMapThemeCollection::masterVisibleLayers() const
+{
+  QList< QgsMapLayer * > visible;
+  Q_FOREACH ( QgsMapLayer *layer, masterLayerOrder() )
+  {
+    QgsLayerTreeLayer *nodeLayer = mProject->layerTreeRoot()->findLayer( layer );
+    if ( nodeLayer )
+    {
+      if ( nodeLayer->isVisible() )
+        visible << layer;
+    }
+  }
+  return visible;
+}
+
 
 bool QgsMapThemeCollection::hasMapTheme( const QString &name ) const
 {

src/core/qgsmapthemecollection.h

@@ -246,9 +246,19 @@ class CORE_EXPORT QgsMapThemeCollection : public QObject
      * Returns the master layer order (this will always match the project's QgsProject::layerOrder() ).
      * All map themes will maintain the same layer order as the master layer order.
      * @note added in QGIS 3.0
+     * @see masterVisibleLayers()
      */
     QList< QgsMapLayer * > masterLayerOrder() const;
 
+    /**
+     * Returns the master list of visible layers. The order of returned layers will always match those
+     * of masterLayerOrder(), but the returned layers are filtered to only include those visible
+     * in the project's layer tree.
+     * @note added in QGIS 3.0
+     * @see masterLayerOrder()
+     */
+    QList< QgsMapLayer * > masterVisibleLayers() const;
+
   signals:
 
     /**

tests/src/python/test_qgsmapthemecollection.py

@@ -102,6 +102,7 @@ def testThemeChanged(self):
     def testMasterLayerOrder(self):
         """ test master layer order"""
         prj = QgsProject.instance()
+        prj.clear()
         layer = QgsVectorLayer("Point?field=fldtxt:string",
                                "layer1", "memory")
         layer2 = QgsVectorLayer("Point?field=fldtxt:string",
@@ -174,6 +175,35 @@ def testMasterLayerOrder(self):
         self.assertEqual(prj.mapThemeCollection().mapThemeVisibleLayers('theme2'), [layer3, layer2, layer])
         self.assertEqual(prj.mapThemeCollection().mapThemeVisibleLayers('theme3'), [layer2, layer])
 
+    def testMasterVisibleLayers(self):
+        """ test master visible layers"""
+        prj = QgsProject.instance()
+        prj.clear()
+        layer = QgsVectorLayer("Point?field=fldtxt:string",
+                               "layer1", "memory")
+        layer2 = QgsVectorLayer("Point?field=fldtxt:string",
+                                "layer2", "memory")
+        layer3 = QgsVectorLayer("Point?field=fldtxt:string",
+                                "layer3", "memory")
+        prj.addMapLayers([layer, layer2, layer3])
+
+        # general setup...
+        prj.setLayerOrder([layer2, layer])
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer2, layer])
+        prj.setLayerOrder([layer3, layer, layer2])
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer3, layer, layer2])
+
+        #hide some layers
+        root = prj.layerTreeRoot()
+        layer_node = root.findLayer(layer2)
+        layer_node.setItemVisibilityChecked(False)
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer3, layer])
+        layer_node.setItemVisibilityChecked(True)
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer3, layer, layer2])
+        layer_node.setItemVisibilityChecked(False)
+        prj.setLayerOrder([layer, layer2, layer3])
+        self.assertEqual(prj.mapThemeCollection().masterVisibleLayers(), [layer, layer3])
+
 
 if __name__ == '__main__':
     unittest.main()