Add method to handle browser item double clicks to QgsDataItemGuiProvider

And move handling of layer/project file double clicks in browser dock
from gui->app

python/gui/auto_generated/qgsbrowserdockwidget.sip.in

@@ -61,12 +61,15 @@ Returns the message bar associated with the dock.
 
   public slots:
 
-    bool addLayerAtIndex( const QModelIndex &index );
+ bool addLayerAtIndex( const QModelIndex &index ) /Deprecated/;
 %Docstring
 Adds the layer corresponding to the specified model ``index``.
 
 Returns true if the index was successfully intrepreted as a map layer and loaded, or
 false if the index is not a map layer or could not be loaded.
+
+.. deprecated:: will be removed in QGIS 4.0 - retrieve the QgsLayerItem itself
+and manually add to project.
 %End
 
     void showContextMenu( QPoint );

python/gui/auto_generated/qgsdataitemguiprovider.sip.in

@@ -97,6 +97,13 @@ The ``context`` argument gives the wider context under which the context menu is
 and contains accessors for useful objects like the application message bar.
 
 The base class method has no effect.
+%End
+
+    virtual bool handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext context );
+%Docstring
+Called when a user double clicks on an ``item``. Providers should return true
+if the double-click was handled and do not want other providers to handle the
+double-click, and to prevent the default double-click behavior for items.
 %End
 
 };

src/app/browser/qgsinbuiltdataitemproviders.cpp

@@ -383,6 +383,23 @@ void QgsLayerItemGuiProvider::populateContextMenu( QgsDataItem *item, QMenu *men
   }
 }
 
+bool QgsLayerItemGuiProvider::handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext )
+{
+  if ( !item || item->type() != QgsDataItem::Layer )
+    return false;
+
+  if ( QgsLayerItem *layerItem = qobject_cast<QgsLayerItem *>( item ) )
+  {
+    const QgsMimeDataUtils::UriList layerUriList = QgsMimeDataUtils::UriList() << layerItem->mimeUri();
+    QgisApp::instance()->handleDropUriList( layerUriList );
+    return true;
+  }
+  else
+  {
+    return false;
+  }
+}
+
 void QgsLayerItemGuiProvider::addLayersFromItems( const QList<QgsDataItem *> &items )
 {
   QgsTemporaryCursorOverride cursor( Qt::WaitCursor );
@@ -394,7 +411,7 @@ void QgsLayerItemGuiProvider::addLayersFromItems( const QList<QgsDataItem *> &it
     if ( item && item->type() == QgsDataItem::Project )
     {
       if ( const QgsProjectItem *projectItem = qobject_cast<const QgsProjectItem *>( item ) )
-        QgisApp::instance()->openFile( projectItem->path(), QStringLiteral( "project" ) );
+        QgisApp::instance()->openProject( projectItem->path() );
 
       return;
     }
@@ -426,3 +443,39 @@ void QgsLayerItemGuiProvider::showPropertiesForItem( QgsLayerItem *item )
   dialog->setItem( item );
   dialog->show();
 }
+
+//
+// QgsProjectItemGuiProvider
+//
+
+QString QgsProjectItemGuiProvider::name()
+{
+  return QStringLiteral( "project_items" );
+}
+
+void QgsProjectItemGuiProvider::populateContextMenu( QgsDataItem *item, QMenu *menu, const QList<QgsDataItem *> &selectedItems, QgsDataItemGuiContext context )
+{
+  if ( !item || item->type() != QgsDataItem::Project )
+    return;
+
+  if ( QgsProjectItem *projectItem = qobject_cast<QgsProjectItem *>( item ) )
+  {
+    // TODO add actions
+  }
+}
+
+bool QgsProjectItemGuiProvider::handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext )
+{
+  if ( !item || item->type() != QgsDataItem::Project )
+    return false;
+
+  if ( QgsProjectItem *projectItem = qobject_cast<QgsProjectItem *>( item ) )
+  {
+    QgisApp::instance()->openProject( projectItem->path() );
+    return true;
+  }
+  else
+  {
+    return false;
+  }
+}

src/app/browser/qgsinbuiltdataitemproviders.h

@@ -94,6 +94,7 @@ class QgsLayerItemGuiProvider : public QObject, public QgsDataItemGuiProvider
 
     void populateContextMenu( QgsDataItem *item, QMenu *menu,
                               const QList<QgsDataItem *> &selectedItems, QgsDataItemGuiContext context ) override;
+    bool handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext context ) override;
 
   private:
 
@@ -103,6 +104,22 @@ class QgsLayerItemGuiProvider : public QObject, public QgsDataItemGuiProvider
 };
 
 
+class QgsProjectItemGuiProvider : public QObject, public QgsDataItemGuiProvider
+{
+    Q_OBJECT
+
+  public:
+
+    QgsProjectItemGuiProvider() = default;
+
+    QString name() override;
+
+    void populateContextMenu( QgsDataItem *item, QMenu *menu,
+                              const QList<QgsDataItem *> &selectedItems, QgsDataItemGuiContext context ) override;
+    bool handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext context ) override;
+
+};
+
 #endif // QGSINBUILTDATAITEMPROVIDERS_H
 
 

src/app/qgisapp.cpp

@@ -1027,6 +1027,7 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
 
   QgsGui::instance()->dataItemGuiProviderRegistry()->addProvider( new QgsAppDirectoryItemGuiProvider() );
   QgsGui::instance()->dataItemGuiProviderRegistry()->addProvider( new QgsProjectHomeItemGuiProvider() );
+  QgsGui::instance()->dataItemGuiProviderRegistry()->addProvider( new QgsProjectItemGuiProvider() );
   QgsGui::instance()->dataItemGuiProviderRegistry()->addProvider( new QgsFavoritesItemGuiProvider() );
   QgsGui::instance()->dataItemGuiProviderRegistry()->addProvider( new QgsLayerItemGuiProvider() );
 

src/app/qgsappbrowserproviders.h

@@ -204,7 +204,6 @@ class APP_EXPORT QgsProjectRootDataItem : public QgsProjectItem
      */
     QgsProjectRootDataItem( QgsDataItem *parent, const QString &path );
     QVector<QgsDataItem *> createChildren() override;
-
 };
 
 /**

src/gui/qgsbrowserdockwidget.cpp

@@ -171,11 +171,17 @@ void QgsBrowserDockWidget::itemDoubleClicked( const QModelIndex &index )
   if ( !item )
     return;
 
-  if ( item->handleDoubleClick() )
-    return;
-  else if ( addLayerAtIndex( index ) ) // default double-click handler
-    return;
-  else
+  QgsDataItemGuiContext context = createContext();
+
+  const QList< QgsDataItemGuiProvider * > providers = QgsGui::instance()->dataItemGuiProviderRegistry()->providers();
+  for ( QgsDataItemGuiProvider *provider : providers )
+  {
+    if ( provider->handleDoubleClick( item, context ) )
+      return;
+  }
+
+  // if no providers overrode the double click handling for this item, we give the item itself a chance
+  if ( !item->handleDoubleClick() )
   {
     // double-click not handled by browser model, so use as default view expand behavior
     if ( mBrowserView->isExpanded( index ) )
@@ -223,8 +229,7 @@ void QgsBrowserDockWidget::showContextMenu( QPoint pt )
     menu->addActions( actions );
   }
 
-  QgsDataItemGuiContext context;
-  context.setMessageBar( mMessageBar );
+  QgsDataItemGuiContext context = createContext();
 
   const QList< QgsDataItemGuiProvider * > providers = QgsGui::instance()->dataItemGuiProviderRegistry()->providers();
   for ( QgsDataItemGuiProvider *provider : providers )
@@ -519,6 +524,13 @@ int QgsBrowserDockWidget::selectedItemsCount()
   return 0;
 }
 
+QgsDataItemGuiContext QgsBrowserDockWidget::createContext()
+{
+  QgsDataItemGuiContext context;
+  context.setMessageBar( mMessageBar );
+  return context;
+}
+
 void QgsBrowserDockWidget::selectionChanged( const QItemSelection &selected, const QItemSelection &deselected )
 {
   Q_UNUSED( selected );

src/gui/qgsbrowserdockwidget.h

@@ -34,6 +34,7 @@ class QgsLayerItem;
 class QgsDataItem;
 class QgsBrowserProxyModel;
 class QgsMessageBar;
+class QgsDataItemGuiContext;
 
 /**
  * \ingroup gui
@@ -87,8 +88,11 @@ class GUI_EXPORT QgsBrowserDockWidget : public QgsDockWidget, private Ui::QgsBro
      *
      * Returns true if the index was successfully intrepreted as a map layer and loaded, or
      * false if the index is not a map layer or could not be loaded.
+     *
+     * \deprecated will be removed in QGIS 4.0 - retrieve the QgsLayerItem itself
+     * and manually add to project.
      */
-    bool addLayerAtIndex( const QModelIndex &index );
+    Q_DECL_DEPRECATED bool addLayerAtIndex( const QModelIndex &index ) SIP_DEPRECATED;
 
     //! Show context menu
     void showContextMenu( QPoint );
@@ -177,6 +181,8 @@ class GUI_EXPORT QgsBrowserDockWidget : public QgsDockWidget, private Ui::QgsBro
     //! Settings prefix (the object name)
     QString settingsSection() { return objectName().toLower(); }
 
+    QgsDataItemGuiContext createContext();
+
     QgsDockBrowserTreeView *mBrowserView = nullptr;
     QgsBrowserModel *mModel = nullptr;
     QgsBrowserProxyModel *mProxyModel = nullptr;

src/gui/qgsdataitemguiprovider.cpp

@@ -38,3 +38,8 @@ void QgsDataItemGuiProvider::populateContextMenu( QgsDataItem *, QMenu *, const
 {
 
 }
+
+bool QgsDataItemGuiProvider::handleDoubleClick( QgsDataItem *, QgsDataItemGuiContext )
+{
+  return false;
+}

src/gui/qgsdataitemguiprovider.h

@@ -113,6 +113,13 @@ class GUI_EXPORT QgsDataItemGuiProvider
     virtual void populateContextMenu( QgsDataItem *item, QMenu *menu,
                                       const QList<QgsDataItem *> &selectedItems, QgsDataItemGuiContext context );
 
+    /**
+     * Called when a user double clicks on an \a item. Providers should return true
+     * if the double-click was handled and do not want other providers to handle the
+     * double-click, and to prevent the default double-click behavior for items.
+     */
+    virtual bool handleDoubleClick( QgsDataItem *item, QgsDataItemGuiContext context );
+
 };
 
 #endif // QGSDATAITEMGUIPROVIDER_H