Layout designers listen out for new item types in registry and

auto create actions for adding new items of the newly registered type

This avoids hard-coding in available item types into layout UI classes,
and allows designers to handle plugin-supplied item types

python/core/layout/qgslayoutitemregistry.sip

@@ -37,6 +37,12 @@ class QgsLayoutItemAbstractMetadata
  :rtype: int
 %End
 
+    virtual QIcon icon() const;
+%Docstring
+ Returns an icon representing the layout item type.
+ :rtype: QIcon
+%End
+
     QString visibleName() const;
 %Docstring
  Returns a translated, user visible name for the layout item class.

src/app/layout/qgslayoutdesignerdialog.cpp

@@ -16,6 +16,7 @@
  ***************************************************************************/
 
 #include "qgslayoutdesignerdialog.h"
+#include "qgslayoutitemregistry.h"
 #include "qgssettings.h"
 #include "qgisapp.h"
 #include "qgslogger.h"
@@ -39,6 +40,7 @@ void QgsAppLayoutDesignerInterface::close()
 QgsLayoutDesignerDialog::QgsLayoutDesignerDialog( QWidget *parent, Qt::WindowFlags flags )
   : QMainWindow( parent, flags )
   , mInterface( new QgsAppLayoutDesignerInterface( this ) )
+  , mToolsActionGroup( new QActionGroup( this ) )
 {
   QgsSettings settings;
   int size = settings.value( QStringLiteral( "IconSize" ), QGIS_ICON_SIZE ).toInt();
@@ -55,6 +57,16 @@ QgsLayoutDesignerDialog::QgsLayoutDesignerDialog( QWidget *parent, Qt::WindowFla
 
   connect( mActionClose, &QAction::triggered, this, &QWidget::close );
 
+  // populate with initial items...
+  QMap< int, QString> types = QgsApplication::layoutItemRegistry()->itemTypes();
+  QMap< int, QString>::const_iterator typeIt = types.constBegin();
+  for ( ; typeIt != types.constEnd(); ++typeIt )
+  {
+    itemTypeAdded( typeIt.key(), typeIt.value() );
+  }
+  //..and listen out for new item types
+  connect( QgsApplication::layoutItemRegistry(), &QgsLayoutItemRegistry::typeAdded, this, &QgsLayoutDesignerDialog::itemTypeAdded );
+
   restoreWindowState();
 }
 
@@ -122,6 +134,23 @@ void QgsLayoutDesignerDialog::closeEvent( QCloseEvent * )
   saveWindowState();
 }
 
+void QgsLayoutDesignerDialog::itemTypeAdded( int type, const QString &name )
+{
+  // update UI for new item type
+  QAction *action = new QAction( tr( "Add %1" ).arg( name ), this );
+  action->setToolTip( tr( "Adds a new %1 to the layout" ).arg( name ) );
+  action->setCheckable( true );
+  action->setData( type );
+  action->setIcon( QgsApplication::layoutItemRegistry()->itemMetadata( type )->icon() );
+  mToolsActionGroup->addAction( action );
+  mItemMenu->addAction( action );
+  mItemToolbar->addAction( action );
+  connect( action, &QAction::triggered, this, [this, type]()
+  {
+    activateNewItemCreationTool( type );
+  } );
+}
+
 void QgsLayoutDesignerDialog::saveWindowState()
 {
   QgsSettings settings;
@@ -147,4 +176,9 @@ void QgsLayoutDesignerDialog::restoreWindowState()
   }
 }
 
+void QgsLayoutDesignerDialog::activateNewItemCreationTool( int type )
+{
+  QgsLogger::debug( QStringLiteral( "creating new %1 item  " ).arg( QgsApplication::layoutItemRegistry()->itemMetadata( type )->visibleName() ) );
+}
+
 

src/app/layout/qgslayoutdesignerdialog.h

@@ -96,18 +96,27 @@ class QgsLayoutDesignerDialog: public QMainWindow, private Ui::QgsLayoutDesigner
 
     virtual void closeEvent( QCloseEvent * ) override;
 
+  private slots:
+
+    void itemTypeAdded( int type, const QString &name );
+
   private:
 
     QgsAppLayoutDesignerInterface *mInterface = nullptr;
 
     QgsLayout *mLayout = nullptr;
 
+    QActionGroup *mToolsActionGroup = nullptr;
+
+
     //! Save window state
     void saveWindowState();
 
     //! Restore the window and toolbar state
     void restoreWindowState();
 
+    //! Switch to new item creation tool, for a new item of the specified \a type.
+    void activateNewItemCreationTool( int type );
 
 };
 

src/core/layout/qgslayoutitemregistry.h

@@ -18,8 +18,10 @@
 
 #include "qgis_core.h"
 #include "qgis_sip.h"
+#include "qgsapplication.h"
 #include "qgspathresolver.h"
 #include <QGraphicsItem> //for QGraphicsItem::UserType
+#include <QIcon>
 #include <functional>
 
 class QgsLayout;
@@ -51,6 +53,11 @@ class CORE_EXPORT QgsLayoutItemAbstractMetadata
      */
     int type() const { return mType; }
 
+    /**
+     * Returns an icon representing the layout item type.
+     */
+    virtual QIcon icon() const { return QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicRectangle.svg" ) ); }
+
     /**
      * Returns a translated, user visible name for the layout item class.
      */
@@ -112,11 +119,12 @@ class CORE_EXPORT QgsLayoutItemMetadata : public QgsLayoutItemAbstractMetadata
      * and \a visibleName, and function pointers for the various item and
      * configuration widget creation functions.
      */
-    QgsLayoutItemMetadata( int type, const QString &visibleName,
+    QgsLayoutItemMetadata( int type, const QString &visibleName, const QIcon &icon,
                            QgsLayoutItemCreateFunc pfCreate,
                            QgsLayoutItemPathResolverFunc pfPathResolver = nullptr,
                            QgsLayoutItemWidgetFunc pfWidget = nullptr )
       : QgsLayoutItemAbstractMetadata( type, visibleName )
+      , mIcon( icon )
       , mCreateFunc( pfCreate )
       , mWidgetFunc( pfWidget )
       , mPathResolverFunc( pfPathResolver )
@@ -144,15 +152,17 @@ class CORE_EXPORT QgsLayoutItemMetadata : public QgsLayoutItemAbstractMetadata
      */
     void setWidgetFunction( QgsLayoutItemWidgetFunc function ) { mWidgetFunc = function; }
 
-    virtual QgsLayoutItem *createItem( QgsLayout *layout, const QVariantMap &properties ) override { return mCreateFunc ? mCreateFunc( layout, properties ) : nullptr; }
-    virtual QWidget *createItemWidget() override { return mWidgetFunc ? mWidgetFunc() : nullptr; }
-    virtual void resolvePaths( QVariantMap &properties, const QgsPathResolver &pathResolver, bool saving ) override
+    QIcon icon() const override { return mIcon.isNull() ? QgsLayoutItemAbstractMetadata::icon() : mIcon; }
+    QgsLayoutItem *createItem( QgsLayout *layout, const QVariantMap &properties ) override { return mCreateFunc ? mCreateFunc( layout, properties ) : nullptr; }
+    QWidget *createItemWidget() override { return mWidgetFunc ? mWidgetFunc() : nullptr; }
+    void resolvePaths( QVariantMap &properties, const QgsPathResolver &pathResolver, bool saving ) override
     {
       if ( mPathResolverFunc )
         mPathResolverFunc( properties, pathResolver, saving );
     }
 
   protected:
+    QIcon mIcon;
     QgsLayoutItemCreateFunc mCreateFunc = nullptr;
     QgsLayoutItemWidgetFunc mWidgetFunc = nullptr;
     QgsLayoutItemPathResolverFunc mPathResolverFunc = nullptr;

src/ui/layout/qgslayoutdesignerbase.ui

@@ -80,19 +80,19 @@
      <height>25</height>
     </rect>
    </property>
-   <widget class="QMenu" name="menuLayout">
+   <widget class="QMenu" name="mLayoutMenu">
     <property name="title">
      <string>&amp;Layout</string>
     </property>
     <addaction name="mActionClose"/>
    </widget>
-   <widget class="QMenu" name="menuItems">
+   <widget class="QMenu" name="mItemMenu">
     <property name="title">
      <string>&amp;Items</string>
     </property>
    </widget>
-   <addaction name="menuLayout"/>
-   <addaction name="menuItems"/>
+   <addaction name="mLayoutMenu"/>
+   <addaction name="mItemMenu"/>
   </widget>
   <action name="mActionClose">
    <property name="text">

tests/src/core/testqgslayoutitem.cpp

@@ -132,7 +132,7 @@ void TestQgsLayoutItem::registry()
 
   QSignalSpy spyTypeAdded( &registry, &QgsLayoutItemRegistry::typeAdded );
 
-  QgsLayoutItemMetadata *metadata = new QgsLayoutItemMetadata( 2, QStringLiteral( "my type" ), create, resolve, createWidget );
+  QgsLayoutItemMetadata *metadata = new QgsLayoutItemMetadata( 2, QStringLiteral( "my type" ), QIcon(), create, resolve, createWidget );
   QVERIFY( registry.addLayoutItemType( metadata ) );
   QCOMPARE( spyTypeAdded.count(), 1 );
   QCOMPARE( spyTypeAdded.value( 0 ).at( 0 ).toInt(), 2 );