Tweaks to layout item combo box

python/core/auto_generated/layout/qgslayoutmodel.sip.in

@@ -155,6 +155,38 @@ Returns the QgsLayoutItem corresponding to an index from the source
 QgsLayoutModel model.
 %End
 
+    QgsLayout *layout();
+%Docstring
+Returns the associated layout.
+
+.. versionadded:: 3.8
+%End
+
+    void setAllowEmptyItem( bool allowEmpty );
+%Docstring
+Sets whether an optional empty layout item is present in the model.
+
+.. seealso:: :py:func:`allowEmptyItem`
+
+.. versionadded:: 3.8
+%End
+
+    bool allowEmptyItem() const;
+%Docstring
+Returns ``True`` if the model includes the empty item choice.
+
+.. seealso:: :py:func:`setAllowEmptyItem`
+
+.. versionadded:: 3.8
+%End
+
+    virtual int rowCount( const QModelIndex &parent = QModelIndex() ) const;
+
+    virtual QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const;
+
+    virtual bool setData( const QModelIndex &index, const QVariant &value, int role = Qt::EditRole );
+
+
   protected:
     virtual bool filterAcceptsRow( int sourceRow, const QModelIndex &sourceParent ) const;
 

python/gui/auto_generated/layout/qgslayoutitemcombobox.sip.in

@@ -33,6 +33,15 @@ until setCurrentLayout() is called
     void setCurrentLayout( QgsLayout *layout );
 %Docstring
 Sets the ``layout`` containing the items to list in the combo box.
+
+.. seealso:: :py:func:`currentLayout`
+%End
+
+    QgsLayout *currentLayout();
+%Docstring
+Returns the current layout containing the items shown in the combo box.
+
+.. seealso:: :py:func:`setCurrentLayout`
 %End
 
     void setItemType( QgsLayoutItemRegistry::ItemType itemType );
@@ -64,6 +73,24 @@ Sets a list of specific items to exclude from the combo box.
 Returns the list of specific items excluded from the combo box.
 
 .. seealso:: :py:func:`setExceptedItemList`
+%End
+
+    void setAllowEmptyItem( bool allowEmpty );
+%Docstring
+Sets whether an optional empty layout item is present in the combobox.
+
+.. seealso:: :py:func:`allowEmptyItem`
+
+.. versionadded:: 3.8
+%End
+
+    bool allowEmptyItem() const;
+%Docstring
+Returns ``True`` if the model includes the empty item choice.
+
+.. seealso:: :py:func:`setAllowEmptyItem`
+
+.. versionadded:: 3.8
 %End
 
     QgsLayoutItem *item( int index ) const;

src/core/layout/qgslayoutmanager.cpp

@@ -323,7 +323,7 @@ QgsLayoutManagerModel::QgsLayoutManagerModel( QgsLayoutManager *manager, QObject
 int QgsLayoutManagerModel::rowCount( const QModelIndex &parent ) const
 {
   Q_UNUSED( parent );
-  return mLayoutManager->layouts().count() + ( mAllowEmpty ? 1 : 0 );
+  return ( mLayoutManager ? mLayoutManager->layouts().count() : 0 ) + ( mAllowEmpty ? 1 : 0 );
 }
 
 QVariant QgsLayoutManagerModel::data( const QModelIndex &index, int role ) const
@@ -339,11 +339,11 @@ QVariant QgsLayoutManagerModel::data( const QModelIndex &index, int role ) const
     case Qt::DisplayRole:
     case Qt::ToolTipRole:
     case Qt::EditRole:
-      return !isEmpty ? mLayoutManager->layouts().at( layoutRow )->name() : QVariant();
+      return !isEmpty && mLayoutManager ? mLayoutManager->layouts().at( layoutRow )->name() : QVariant();
 
     case LayoutRole:
     {
-      if ( isEmpty )
+      if ( isEmpty || !mLayoutManager )
         return QVariant();
       else if ( QgsLayout *l = dynamic_cast< QgsLayout * >( mLayoutManager->layouts().at( layoutRow ) ) )
         return QVariant::fromValue( l );
@@ -355,7 +355,7 @@ QVariant QgsLayoutManagerModel::data( const QModelIndex &index, int role ) const
 
     case Qt::DecorationRole:
     {
-      return isEmpty ? QIcon() : mLayoutManager->layouts().at( layoutRow )->icon();
+      return isEmpty || !mLayoutManager ? QIcon() : mLayoutManager->layouts().at( layoutRow )->icon();
     }
 
     default:

src/core/layout/qgslayoutmodel.cpp

@@ -958,6 +958,13 @@ QgsLayoutProxyModel::QgsLayoutProxyModel( QgsLayout *layout, QObject *parent )
 
 bool QgsLayoutProxyModel::lessThan( const QModelIndex &left, const QModelIndex &right ) const
 {
+  const QString leftText = sourceModel()->data( left, Qt::DisplayRole ).toString();
+  const QString rightText = sourceModel()->data( right, Qt::DisplayRole ).toString();
+  if ( leftText.isEmpty() )
+    return true;
+  if ( rightText.isEmpty() )
+    return false;
+
   //sort by item id
   const QgsLayoutItem *item1 = itemFromSourceIndex( left );
   const QgsLayoutItem *item2 = itemFromSourceIndex( right );
@@ -970,6 +977,35 @@ bool QgsLayoutProxyModel::lessThan( const QModelIndex &left, const QModelIndex &
   return QString::localeAwareCompare( item1->displayName(), item2->displayName() ) < 0;
 }
 
+int QgsLayoutProxyModel::rowCount( const QModelIndex &parent ) const
+{
+  return QSortFilterProxyModel::rowCount( parent ) + ( mAllowEmpty ? 1 : 0 );
+}
+
+QVariant QgsLayoutProxyModel::data( const QModelIndex &index, int role ) const
+{
+  if ( mAllowEmpty && index.row() == rowCount() - 1 )
+  {
+    return QVariant();
+  }
+  else
+  {
+    return QSortFilterProxyModel::data( index, role );
+  }
+}
+
+bool QgsLayoutProxyModel::setData( const QModelIndex &index, const QVariant &value, int role )
+{
+  if ( mAllowEmpty && index.row() == rowCount() - 1 )
+  {
+    return false;
+  }
+  else
+  {
+    return QSortFilterProxyModel::setData( index, value, role );
+  }
+}
+
 QgsLayoutItem *QgsLayoutProxyModel::itemFromSourceIndex( const QModelIndex &sourceIndex ) const
 {
   if ( !mLayout )
@@ -980,6 +1016,17 @@ QgsLayoutItem *QgsLayoutProxyModel::itemFromSourceIndex( const QModelIndex &sour
   return qobject_cast<QgsLayoutItem *>( itemAsVariant.value<QObject *>() );
 }
 
+void QgsLayoutProxyModel::setAllowEmptyItem( bool allowEmpty )
+{
+  mAllowEmpty = allowEmpty;
+  invalidateFilter();
+}
+
+bool QgsLayoutProxyModel::allowEmptyItem() const
+{
+  return mAllowEmpty;
+}
+
 void QgsLayoutProxyModel::setFilterType( QgsLayoutItemRegistry::ItemType filter )
 {
   mItemTypeFilter = filter;
@@ -1002,7 +1049,7 @@ bool QgsLayoutProxyModel::filterAcceptsRow( int sourceRow, const QModelIndex &so
   QgsLayoutItem *item = itemFromSourceIndex( index );
 
   if ( !item )
-    return false;
+    return mAllowEmpty;
 
   // specific exceptions
   if ( mExceptedList.contains( item ) )

src/core/layout/qgslayoutmodel.h

@@ -352,6 +352,30 @@ class CORE_EXPORT QgsLayoutProxyModel: public QSortFilterProxyModel
      */
     QgsLayoutItem *itemFromSourceIndex( const QModelIndex &sourceIndex ) const;
 
+    /**
+     * Returns the associated layout.
+     * \since QGIS 3.8
+     */
+    QgsLayout *layout() { return mLayout; }
+
+    /**
+     * Sets whether an optional empty layout item is present in the model.
+     * \see allowEmptyItem()
+     * \since QGIS 3.8
+     */
+    void setAllowEmptyItem( bool allowEmpty );
+
+    /**
+     * Returns TRUE if the model includes the empty item choice.
+     * \see setAllowEmptyItem()
+     * \since QGIS 3.8
+     */
+    bool allowEmptyItem() const;
+
+    int rowCount( const QModelIndex &parent = QModelIndex() ) const override;
+    QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const override;
+    bool setData( const QModelIndex &index, const QVariant &value, int role = Qt::EditRole ) override;
+
   protected:
     bool filterAcceptsRow( int sourceRow, const QModelIndex &sourceParent ) const override;
     bool lessThan( const QModelIndex &left, const QModelIndex &right ) const override;
@@ -360,6 +384,7 @@ class CORE_EXPORT QgsLayoutProxyModel: public QSortFilterProxyModel
     QgsLayout *mLayout = nullptr;
     QgsLayoutItemRegistry::ItemType mItemTypeFilter;
     QList< QgsLayoutItem * > mExceptedList;
+    bool mAllowEmpty = false;
 
 };
 

src/gui/layout/qgslayoutitemcombobox.cpp

@@ -35,6 +35,11 @@ void QgsLayoutItemComboBox::setCurrentLayout( QgsLayout *layout )
   mProxyModel->sort( 0, Qt::AscendingOrder );
 }
 
+QgsLayout *QgsLayoutItemComboBox::currentLayout()
+{
+  return mProxyModel->layout();
+}
+
 void QgsLayoutItemComboBox::setItem( const QgsLayoutItem *item )
 {
   if ( !mProxyModel->sourceLayerModel() )
@@ -50,7 +55,7 @@ void QgsLayoutItemComboBox::setItem( const QgsLayoutItem *item )
       return;
     }
   }
-  setCurrentIndex( -1 );
+  setCurrentIndex( mProxyModel->allowEmptyItem() ? 0 : -1 );
 }
 
 QgsLayoutItem *QgsLayoutItemComboBox::currentItem() const
@@ -97,6 +102,16 @@ QList< QgsLayoutItem *> QgsLayoutItemComboBox::exceptedItemList() const
   return mProxyModel->exceptedItemList();
 }
 
+void QgsLayoutItemComboBox::setAllowEmptyItem( bool allowEmpty )
+{
+  mProxyModel->setAllowEmptyItem( allowEmpty );
+}
+
+bool QgsLayoutItemComboBox::allowEmptyItem() const
+{
+  return mProxyModel->allowEmptyItem();
+}
+
 QgsLayoutItem *QgsLayoutItemComboBox::item( int index ) const
 {
   const QModelIndex proxyIndex = mProxyModel->index( index, 0 );

src/gui/layout/qgslayoutitemcombobox.h

@@ -46,9 +46,18 @@ class GUI_EXPORT QgsLayoutItemComboBox : public QComboBox
 
     /**
      * Sets the \a layout containing the items to list in the combo box.
+     *
+     * \see currentLayout()
      */
     void setCurrentLayout( QgsLayout *layout );
 
+    /**
+      * Returns the current layout containing the items shown in the combo box.
+      *
+      * \see setCurrentLayout()
+      */
+    QgsLayout *currentLayout();
+
     /**
      * Sets a filter for the item type to show in the combo box.
      * \param itemType type of items to show. Set to QgsLayoutItemRegistry::LayoutItem to
@@ -75,6 +84,20 @@ class GUI_EXPORT QgsLayoutItemComboBox : public QComboBox
      */
     QList< QgsLayoutItem * > exceptedItemList() const;
 
+    /**
+     * Sets whether an optional empty layout item is present in the combobox.
+     * \see allowEmptyItem()
+     * \since QGIS 3.8
+     */
+    void setAllowEmptyItem( bool allowEmpty );
+
+    /**
+     * Returns TRUE if the model includes the empty item choice.
+     * \see setAllowEmptyItem()
+     * \since QGIS 3.8
+     */
+    bool allowEmptyItem() const;
+
     /**
      * Returns the item currently shown at the specified \a index within the combo box.
      * \see currentItem()

tests/src/core/testqgslayoutmodel.cpp

@@ -21,6 +21,7 @@
 #include "qgsapplication.h"
 #include "qgsmapsettings.h"
 #include "qgsproject.h"
+#include "qgslayoutitemlabel.h"
 
 #include <QObject>
 #include "qgstest.h"
@@ -58,6 +59,7 @@ class TestQgsLayoutModel : public QObject
     void reorderToTopWithRemoved(); //test reordering to top with removed items
     void reorderToBottomWithRemoved(); //test reordering to bottom with removed items
 
+    void proxy();
     void proxyCrash();
 
 };
@@ -771,6 +773,48 @@ void TestQgsLayoutModel::reorderToBottomWithRemoved()
   QCOMPARE( layout.itemsModel()->mItemsInScene.at( 1 ), item2 );
 }
 
+void TestQgsLayoutModel::proxy()
+{
+  QgsLayout *layout = new QgsLayout( QgsProject::instance() );
+  QgsLayoutProxyModel *proxy = new QgsLayoutProxyModel( layout );
+  // add some items to composition
+  QgsLayoutItemMap *item1 = new QgsLayoutItemMap( layout );
+  item1->setId( QStringLiteral( "c" ) );
+  layout->addLayoutItem( item1 );
+  QgsLayoutItemMap *item2 = new QgsLayoutItemMap( layout );
+  item2->setId( QStringLiteral( "b" ) );
+  layout->addLayoutItem( item2 );
+  QgsLayoutItemLabel *item3 = new QgsLayoutItemLabel( layout );
+  item3->setId( QStringLiteral( "a" ) );
+  layout->addLayoutItem( item3 );
+  QCOMPARE( proxy->rowCount( QModelIndex() ), 3 );
+  QCOMPARE( proxy->data( proxy->index( 0, 2, QModelIndex() ) ).toString(), QStringLiteral( "a" ) );
+  QCOMPARE( proxy->data( proxy->index( 1, 2, QModelIndex() ) ).toString(), QStringLiteral( "b" ) );
+  QCOMPARE( proxy->data( proxy->index( 2, 2, QModelIndex() ) ).toString(), QStringLiteral( "c" ) );
+
+  proxy->setAllowEmptyItem( true );
+  QCOMPARE( proxy->rowCount( QModelIndex() ), 4 );
+  QCOMPARE( proxy->data( proxy->index( 0, 2, QModelIndex() ) ).toString(), QStringLiteral( "a" ) );
+  QCOMPARE( proxy->data( proxy->index( 1, 2, QModelIndex() ) ).toString(), QStringLiteral( "b" ) );
+  QCOMPARE( proxy->data( proxy->index( 2, 2, QModelIndex() ) ).toString(), QStringLiteral( "c" ) );
+  QCOMPARE( proxy->data( proxy->index( 3, 2, QModelIndex() ) ).toString(), QString() );
+
+  proxy->setFilterType( QgsLayoutItemRegistry::LayoutMap );
+  QCOMPARE( proxy->rowCount( QModelIndex() ), 3 );
+  QCOMPARE( proxy->data( proxy->index( 0, 2, QModelIndex() ) ).toString(), QStringLiteral( "b" ) );
+  QCOMPARE( proxy->data( proxy->index( 1, 2, QModelIndex() ) ).toString(), QStringLiteral( "c" ) );
+  QCOMPARE( proxy->data( proxy->index( 2, 2, QModelIndex() ) ).toString(), QString() );
+
+  proxy->setFilterType( QgsLayoutItemRegistry::LayoutLabel );
+  QCOMPARE( proxy->rowCount( QModelIndex() ), 2 );
+  QCOMPARE( proxy->data( proxy->index( 0, 2, QModelIndex() ) ).toString(), QStringLiteral( "a" ) );
+  QCOMPARE( proxy->data( proxy->index( 1, 2, QModelIndex() ) ).toString(), QString() );
+
+  proxy->setFilterType( QgsLayoutItemRegistry::LayoutScaleBar );
+  QCOMPARE( proxy->rowCount( QModelIndex() ), 1 );
+  QCOMPARE( proxy->data( proxy->index( 0, 2, QModelIndex() ) ).toString(), QString() );
+}
+
 void TestQgsLayoutModel::proxyCrash()
 {
   // test for a possible crash when using QgsComposerProxyModel and reordering items