Correctly create undo commands for item addition and removal

src/core/layout/qgslayout.cpp

@@ -372,6 +372,7 @@ void QgsLayout::removeLayoutItem( QgsLayoutItem *item )
 #if 0 //TODO
   emit itemRemoved( item );
 #endif
+  item->deleteLater();
 }
 
 QgsLayoutUndoStack *QgsLayout::undoStack()

src/core/layout/qgslayoutitemundocommand.cpp

@@ -116,8 +116,39 @@ void QgsLayoutItemDeleteUndoCommand::redo()
   QgsLayoutItem *item = layout()->itemByUuid( itemUuid() );
   Q_ASSERT_X( item, "QgsLayoutItemDeleteUndoCommand::redo", "could not find item to re-delete!" );
 
-  layout()->removeItem( item );
-  item->deleteLater();
+  layout()->removeLayoutItem( item );
 }
 
+QgsLayoutItemAddItemCommand::QgsLayoutItemAddItemCommand( QgsLayoutItem *item, const QString &text, int id, QUndoCommand *parent )
+  : QgsLayoutItemUndoCommand( item, text, id, parent )
+{
+  saveAfterState();
+}
+
+bool QgsLayoutItemAddItemCommand::containsChange() const
+{
+  return true;
+}
+
+bool QgsLayoutItemAddItemCommand::mergeWith( const QUndoCommand * )
+{
+  return false;
+}
+
+void QgsLayoutItemAddItemCommand::undo()
+{
+  if ( mFirstRun )
+  {
+    mFirstRun = false;
+    return;
+  }
+
+  QgsLayoutItem *item = layout()->itemByUuid( itemUuid() );
+  if ( item )
+  {
+    layout()->removeLayoutItem( item );
+  }
+}
+
+
 ///@endcond

src/core/layout/qgslayoutitemundocommand.h

@@ -107,6 +107,35 @@ class CORE_EXPORT QgsLayoutItemDeleteUndoCommand: public QgsLayoutItemUndoComman
 
 };
 
+
+/**
+ * \ingroup core
+ * An undo command subclass for layout item addition undo commands.
+ *
+ * QgsLayoutItemAddItemCommand is a specific layout undo command which handles
+ * layout item creation. When applied (e.g. as a result of a 'redo' action),
+ * the associated layout item is recreated and added to the layout.
+ *
+ * \since QGIS 3.0
+*/
+class CORE_EXPORT QgsLayoutItemAddItemCommand: public QgsLayoutItemUndoCommand
+{
+  public:
+
+    /**
+     * Constructor for QgsLayoutItemAddItemCommand.
+     * \param item associated layout item
+     * \param text undo command descriptive text
+     * \param id optional undo command id, used for automatic command merging
+     * \param parent command
+     */
+    QgsLayoutItemAddItemCommand( QgsLayoutItem *item, const QString &text, int id = 0, QUndoCommand *parent SIP_TRANSFERTHIS = nullptr );
+    bool containsChange() const override;
+    bool mergeWith( const QUndoCommand *command ) override;
+    void undo() override;
+
+};
+
 ///@endcond
 
 #endif

src/gui/layout/qgslayoutview.cpp

@@ -28,6 +28,8 @@
 #include "qgssettings.h"
 #include "qgsrectangle.h"
 #include "qgsapplication.h"
+#include "qgslayoutitemundocommand.h"
+#include "qgsproject.h"
 #include <memory>
 #include <QDesktopWidget>
 #include <QMenu>
@@ -583,9 +585,12 @@ void QgsLayoutView::deleteSelectedItems()
     //delete selected items
     for ( QgsLayoutItem *item : selectedItems )
     {
+      QgsLayoutItemDeleteUndoCommand *deleteCommand = new QgsLayoutItemDeleteUndoCommand( item, QString() );
       currentLayout()->removeLayoutItem( item );
+      currentLayout()->undoStack()->stack()->push( deleteCommand );
     }
     currentLayout()->undoStack()->endMacro();
+    currentLayout()->project()->setDirty( true );
 
 #if 0
   }

src/gui/layout/qgslayoutviewtooladditem.cpp

@@ -26,6 +26,7 @@
 #include "qgslayoutitemguiregistry.h"
 #include "qgslayoutnewitempropertiesdialog.h"
 #include "qgssettings.h"
+#include "qgslayoutitemundocommand.h"
 #include <QGraphicsRectItem>
 #include <QPen>
 #include <QBrush>
@@ -118,6 +119,7 @@ void QgsLayoutViewToolAddItem::layoutReleaseEvent( QgsLayoutViewMouseEvent *even
   settings.setValue( QStringLiteral( "LayoutDesigner/lastSizeUnit" ), static_cast< int >( item->sizeWithUnits().units() ) );
 
   layout()->addLayoutItem( item );
+  layout()->undoStack()->stack()->push( new QgsLayoutItemAddItemCommand( item, tr( "Created %1" ).arg( QgsApplication::layoutItemRegistry()->itemMetadata( mItemType )->visibleName() ) ) );
   layout()->setSelectedItem( item );
 }