Add a method to clear an existing layout

python/core/layout/qgslayout.sip

@@ -49,6 +49,13 @@ class QgsLayout : QGraphicsScene, QgsExpressionContextGenerator, QgsLayoutUndoOb
  a new layout.
 %End
 
+    void clear();
+%Docstring
+ Clears the layout.
+
+ Calling this method removes all items and pages from the layout.
+%End
+
     QgsProject *project() const;
 %Docstring
  The project associated with the layout. Used to get access to layers, map themes,

src/core/layout/qgslayout.cpp

@@ -81,6 +81,27 @@ void QgsLayout::initializeDefaults()
   mUndoStack->stack()->clear();
 }
 
+void QgsLayout::clear()
+{
+  deleteAndRemoveMultiFrames();
+
+  //delete all non paper items
+  const QList<QGraphicsItem *> itemList = items();
+  for ( QGraphicsItem *item : itemList )
+  {
+    QgsLayoutItem *cItem = dynamic_cast<QgsLayoutItem *>( item );
+    QgsLayoutItemPage *pItem = dynamic_cast<QgsLayoutItemPage *>( item );
+    if ( cItem && !pItem )
+    {
+      removeLayoutItemPrivate( cItem );
+    }
+  }
+  mItemsModel->clear();
+
+  mPageCollection->clear();
+  mUndoStack->stack()->clear();
+}
+
 QgsProject *QgsLayout::project() const
 {
   return mProject;

src/core/layout/qgslayout.h

@@ -73,6 +73,13 @@ class CORE_EXPORT QgsLayout : public QGraphicsScene, public QgsExpressionContext
      */
     void initializeDefaults();
 
+    /**
+     * Clears the layout.
+     *
+     * Calling this method removes all items and pages from the layout.
+     */
+    void clear();
+
     /**
      * The project associated with the layout. Used to get access to layers, map themes,
      * relations and various other bits. It is never null.

tests/src/core/testqgslayout.cpp

@@ -44,6 +44,7 @@ class TestQgsLayout: public QObject
     void undoRedoOccurred();
     void itemsOnPage(); //test fetching matching items on a set page
     void pageIsEmpty();
+    void clear();
 
   private:
     QString mReport;
@@ -609,6 +610,43 @@ void TestQgsLayout::pageIsEmpty()
   QCOMPARE( l.pageCollection()->pageIsEmpty( 2 ), true );
 }
 
+void TestQgsLayout::clear()
+{
+  QgsProject proj;
+  QgsLayout l( &proj );
+  QgsLayoutItemPage *page = new QgsLayoutItemPage( &l );
+  page->setPageSize( "A4" );
+  l.pageCollection()->addPage( page );
+  QgsLayoutItemPage *page2 = new QgsLayoutItemPage( &l );
+  page2->setPageSize( "A4" );
+  l.pageCollection()->addPage( page2 );
+  QgsLayoutItemPage *page3 = new QgsLayoutItemPage( &l );
+  page3->setPageSize( "A4" );
+  l.pageCollection()->addPage( page3 );
+
+  //add some items to the composition
+  QgsLayoutItemShape *label1 = new QgsLayoutItemShape( &l );
+  l.addLayoutItem( label1 );
+  QPointer< QgsLayoutItem > item1P = label1;
+  QgsLayoutItemShape *label2 = new QgsLayoutItemShape( &l );
+  l.addLayoutItem( label2 );
+  QPointer< QgsLayoutItem > item2P = label2;
+  QgsLayoutItemShape *label3 = new QgsLayoutItemShape( &l );
+  l.addLayoutItem( label3 );
+  QPointer< QgsLayoutItem > item3P = label3;
+
+  l.clear();
+  QgsApplication::sendPostedEvents( nullptr, QEvent::DeferredDelete );
+  QCOMPARE( l.pageCollection()->pageCount(), 0 );
+  QVERIFY( !item1P );
+  QVERIFY( !item2P );
+  QVERIFY( !item3P );
+  QList< QgsLayoutItem * > items;
+  l.layoutItems( items );
+  QVERIFY( items.empty() );
+  QCOMPARE( l.undoStack()->stack()->count(), 0 );
+}
+
 
 QGSTEST_MAIN( TestQgsLayout )
 #include "testqgslayout.moc"