ENH: Improve empty folder visibility logic

- The SH tree view saves the "current tree view" pointer in the SH plugin handler
- When the user creates a new folder, the folder plugin enables showing empty folders in the sort filter proxy model of the current tree view, and stores the tree view pointer in a list
- Right-clicking on scene or any item, the folder plugin shows a new "Show empty folders" action if the user has created a new folder from that tree view (i.e. the current tree view is in the list)
- Make the DICOM SH plugin behave the same way as the Folder plugin
- Fix issue in sort filter proxy model where the folder disappeared from Markups module when changing visibility. (If the ShowEmptyHierarchyItems flag is on, we expect all the folder type items to show up even if they do not have children or none of them are visible. However, since a vtkMRMLFolderDisplayNode type data node is added to the folder item after changing visibility, it may be filtered out by a node type filter, which is applied for example in the Markups tree view. In this case, the folder would only show up if any of its children were visible. This commit makes sure that if the ShowEmptyHierarchyItems flag is on, the data node type filter does not override it.)

Re Slicer#6596

Modules/Loadable/SubjectHierarchy/Widgets/qMRMLSortFilterSubjectHierarchyProxyModel.cxx

@@ -1001,10 +1001,19 @@ qMRMLSortFilterSubjectHierarchyProxyModel::AcceptType qMRMLSortFilterSubjectHier
       }
     }
 
-  // Hide hierarchy item if none of its children are accepted and the corresponding filter is turned on
-  if (!d->ShowEmptyHierarchyItems && (!dataNode || dataNode->IsA("vtkMRMLFolderDisplayNode")))
+  if (!dataNode || dataNode->IsA("vtkMRMLFolderDisplayNode"))
     {
-    onlyAcceptIfAnyChildIsAccepted = true;
+    if (d->ShowEmptyHierarchyItems)
+      {
+      // Reset this flag if item is a hierarchy item and it should be shown even if empty.
+      // (The flag may have been set before if node type filter was set, which did not include the folder display node)
+      onlyAcceptIfAnyChildIsAccepted = false;
+      }
+    else
+      {
+      // Hide hierarchy item if none of its children are accepted and the corresponding filter is turned on
+      onlyAcceptIfAnyChildIsAccepted = true;
+      }
     }
 
   // If the visibility of an item depends on whether any of its children are shown, then evaluate that condition

Modules/Loadable/SubjectHierarchy/Widgets/qMRMLSubjectHierarchyTreeView.cxx

@@ -2633,6 +2633,9 @@ void qMRMLSubjectHierarchyTreeView::onCustomContextMenu(const QPoint& point)
       }
     }
 
+  // Save tree view for the plugins to access if needed
+  qSlicerSubjectHierarchyPluginHandler::instance()->setCurrentTreeView(this);
+
   // Get subject hierarchy item at mouse click position
   vtkIdType itemID = this->sortFilterProxyModel()->subjectHierarchyItemFromIndex(index);
   // Populate context menu for the current item

Modules/Loadable/SubjectHierarchy/Widgets/qSlicerSubjectHierarchyFolderPlugin.cxx

@@ -24,7 +24,9 @@
 #include "vtkMRMLSubjectHierarchyConstants.h"
 #include "vtkMRMLSubjectHierarchyNode.h"
 
-// SubjectHierarchy Plugins includes
+// SubjectHierarchy Widgets includes
+#include "qMRMLSortFilterSubjectHierarchyProxyModel.h"
+#include "qMRMLSubjectHierarchyTreeView.h"
 #include "qSlicerSubjectHierarchyPluginHandler.h"
 #include "qSlicerSubjectHierarchyFolderPlugin.h"
 #include "qSlicerSubjectHierarchyDefaultPlugin.h"
@@ -63,8 +65,10 @@ class qSlicerSubjectHierarchyFolderPluginPrivate: public QObject
   QAction* CreateFolderUnderSceneAction;
   QAction* CreateFolderUnderNodeAction;
   QAction* ApplyColorToBranchAction;
+  QAction* ShowEmptyFoldersAction;
 
   QString AddedByFolderPluginAttributeName;
+  QList<qMRMLSubjectHierarchyTreeView*> TreeViewsToShowEmptyFolderAction;
 };
 
 //-----------------------------------------------------------------------------
@@ -79,6 +83,7 @@ qSlicerSubjectHierarchyFolderPluginPrivate::qSlicerSubjectHierarchyFolderPluginP
   this->CreateFolderUnderSceneAction = nullptr;
   this->CreateFolderUnderNodeAction = nullptr;
   this->ApplyColorToBranchAction = nullptr;
+  this->ShowEmptyFoldersAction = nullptr;
 
   std::string addedByFolderPluginAttributeNameStr =
       vtkMRMLSubjectHierarchyConstants::GetSubjectHierarchyAttributePrefix()
@@ -108,6 +113,14 @@ void qSlicerSubjectHierarchyFolderPluginPrivate::init()
     qSlicerSubjectHierarchyAbstractPlugin::SectionFolder, 7);
   QObject::connect(this->ApplyColorToBranchAction, SIGNAL(toggled(bool)), q, SLOT(onApplyColorToBranchToggled(bool)));
   this->ApplyColorToBranchAction->setCheckable(true);
+
+  this->ShowEmptyFoldersAction = new QAction(qSlicerSubjectHierarchyFolderPlugin::tr("Show empty folders"), q);
+  this->ShowEmptyFoldersAction->setToolTip(
+    qSlicerSubjectHierarchyFolderPlugin::tr("If on, then folders that do not contain nodes (allowed by any filter) are shown, otherwise not"));
+  qSlicerSubjectHierarchyAbstractPlugin::setActionPosition(this->ShowEmptyFoldersAction,
+    qSlicerSubjectHierarchyAbstractPlugin::SectionFolder, 8);
+  QObject::connect(this->ShowEmptyFoldersAction, SIGNAL(toggled(bool)), q, SLOT(onShowEmptyFoldersToggled(bool)));
+  this->ShowEmptyFoldersAction->setCheckable(true);
 }
 
 //-----------------------------------------------------------------------------
@@ -384,7 +397,7 @@ QList<QAction*> qSlicerSubjectHierarchyFolderPlugin::itemContextMenuActions()con
   Q_D(const qSlicerSubjectHierarchyFolderPlugin);
 
   QList<QAction*> actions;
-  actions << d->CreateFolderUnderNodeAction;
+  actions << d->CreateFolderUnderNodeAction << d->ShowEmptyFoldersAction;
   return actions;
 }
 
@@ -394,7 +407,7 @@ QList<QAction*> qSlicerSubjectHierarchyFolderPlugin::sceneContextMenuActions()co
   Q_D(const qSlicerSubjectHierarchyFolderPlugin);
 
   QList<QAction*> actions;
-  actions << d->CreateFolderUnderSceneAction << d->ApplyColorToBranchAction;
+  actions << d->CreateFolderUnderSceneAction << d->ApplyColorToBranchAction << d->ShowEmptyFoldersAction;
   return actions;
 }
 
@@ -414,13 +427,20 @@ void qSlicerSubjectHierarchyFolderPlugin::showContextMenuActionsForItem(vtkIdTyp
   if (itemID == shNode->GetSceneItemID())
     {
     d->CreateFolderUnderSceneAction->setVisible(true);
+
+    // Show the Show empty folder action if the current tree view has created a folder before. Update checked state if visible.
+    this->updateShowEmptyFoldersAction();
+
     return;
     }
 
-  // Folder can be created under any node
   if (itemID)
     {
+    // Folder can be created under any node
     d->CreateFolderUnderNodeAction->setVisible(true);
+
+    // Show the Show empty folder action if the current tree view has created a folder before. Update checked state if visible.
+    this->updateShowEmptyFoldersAction();
     }
 
   // Folder
@@ -435,6 +455,26 @@ void qSlicerSubjectHierarchyFolderPlugin::showContextMenuActionsForItem(vtkIdTyp
     }
 }
 
+//---------------------------------------------------------------------------
+void qSlicerSubjectHierarchyFolderPlugin::updateShowEmptyFoldersAction()
+{
+  Q_D(const qSlicerSubjectHierarchyFolderPlugin);
+
+  qMRMLSubjectHierarchyTreeView* currentTreeView = qSlicerSubjectHierarchyPluginHandler::instance()->currentTreeView();
+  if (currentTreeView)
+    {
+    qMRMLSortFilterSubjectHierarchyProxyModel* sortFilterProxyModel = currentTreeView->sortFilterProxyModel();
+    d->ShowEmptyFoldersAction->blockSignals(true);
+    d->ShowEmptyFoldersAction->setChecked(sortFilterProxyModel->showEmptyHierarchyItems());
+    d->ShowEmptyFoldersAction->blockSignals(false);
+    d->ShowEmptyFoldersAction->setVisible(d->TreeViewsToShowEmptyFolderAction.contains(currentTreeView));
+    }
+  else
+    {
+    d->ShowEmptyFoldersAction->setVisible(false);
+    }
+}
+
 //---------------------------------------------------------------------------
 QList<QAction*> qSlicerSubjectHierarchyFolderPlugin::visibilityContextMenuActions()const
 {
@@ -482,6 +522,7 @@ void qSlicerSubjectHierarchyFolderPlugin::editProperties(vtkIdType itemID)
 //---------------------------------------------------------------------------
 vtkIdType qSlicerSubjectHierarchyFolderPlugin::createFolderUnderItem(vtkIdType parentItemID)
 {
+  Q_D(qSlicerSubjectHierarchyFolderPlugin);
   vtkMRMLScene* scene = qSlicerSubjectHierarchyPluginHandler::instance()->mrmlScene();
   if (!scene)
     {
@@ -502,6 +543,15 @@ vtkIdType qSlicerSubjectHierarchyFolderPlugin::createFolderUnderItem(vtkIdType p
   vtkIdType childItemID = shNode->CreateFolderItem(parentItemID, name);
   emit requestExpandItem(childItemID);
 
+  // Make sure empty folders are shown in the tree view it was created in
+  qMRMLSubjectHierarchyTreeView* currentTreeView = qSlicerSubjectHierarchyPluginHandler::instance()->currentTreeView();
+  if (currentTreeView)
+    {
+    qMRMLSortFilterSubjectHierarchyProxyModel* sortFilterProxyModel = currentTreeView->sortFilterProxyModel();
+    sortFilterProxyModel->setShowEmptyHierarchyItems(true);
+    this->emptyFolderCreatedFromTreeView(currentTreeView);
+    }
+
   return childItemID;
 }
 
@@ -550,6 +600,20 @@ void qSlicerSubjectHierarchyFolderPlugin::onApplyColorToBranchToggled(bool on)
   this->setApplyColorToBranchEnabledForItem(currentItemID, on);
 }
 
+//-----------------------------------------------------------------------------
+void qSlicerSubjectHierarchyFolderPlugin::onShowEmptyFoldersToggled(bool on)
+{
+  qMRMLSubjectHierarchyTreeView* currentTreeView = qSlicerSubjectHierarchyPluginHandler::instance()->currentTreeView();
+  if (!currentTreeView)
+    {
+    qCritical() << Q_FUNC_INFO << ": Failed to access current subject hierarchy tree view";
+    return;
+    }
+
+  qMRMLSortFilterSubjectHierarchyProxyModel* sortFilterProxyModel = currentTreeView->sortFilterProxyModel();
+  sortFilterProxyModel->setShowEmptyHierarchyItems(on);
+}
+
 //-----------------------------------------------------------------------------
 vtkMRMLDisplayNode* qSlicerSubjectHierarchyFolderPlugin::displayNodeForItem(vtkIdType itemID)const
 {
@@ -663,3 +727,15 @@ void qSlicerSubjectHierarchyFolderPlugin::setApplyColorToBranchEnabledForItem(vt
 
   folderDisplayNode->SetApplyDisplayPropertiesOnBranch(enabled);
 }
+
+//-----------------------------------------------------------------------------
+void qSlicerSubjectHierarchyFolderPlugin::emptyFolderCreatedFromTreeView(qMRMLSubjectHierarchyTreeView* treeView)
+{
+  Q_D(qSlicerSubjectHierarchyFolderPlugin);
+
+  if (!d->TreeViewsToShowEmptyFolderAction.contains(treeView))
+    {
+    // Only add the tree view in the list if not already there
+    d->TreeViewsToShowEmptyFolderAction.push_back(treeView);
+    }
+}

Modules/Loadable/SubjectHierarchy/Widgets/qSlicerSubjectHierarchyFolderPlugin.h

@@ -31,6 +31,7 @@
 // CTK includes
 #include <ctkVTKObject.h>
 
+class qMRMLSubjectHierarchyTreeView;
 class qSlicerSubjectHierarchyFolderPluginPrivate;
 
 class vtkMRMLDisplayNode;
@@ -149,6 +150,10 @@ class Q_SLICER_MODULE_SUBJECTHIERARCHY_WIDGETS_EXPORT qSlicerSubjectHierarchyFol
   /// node, then create a display node associated to that. Otherwise create display node for folder item
   vtkMRMLDisplayNode* createDisplayNodeForItem(vtkIdType itemID);
 
+  /// Add tree view to the list of view from which empty folders have been created.
+  /// This function is called from the DICOM plugin, which can create patient and study items (which are special folders).
+  void emptyFolderCreatedFromTreeView(qMRMLSubjectHierarchyTreeView* treeView);
+
 protected slots:
   /// Create folder node under the scene
   void createFolderUnderScene();
@@ -159,6 +164,9 @@ protected slots:
   /// Toggle apply color to branch
   void onApplyColorToBranchToggled(bool);
 
+  /// Toggle empty folder visibility (\sa showEmptyHierarchyItems) in the sort filter proxy model of the current tree view.
+  void onShowEmptyFoldersToggled(bool);
+
 protected:
   /// Retrieve model display node for given item. If the folder item has an associated model display
   /// node (created by the plugin), then return that. Otherwise see if it has a model hierarchy node
@@ -170,6 +178,10 @@ protected slots:
   /// Determine if apply color to branch option is enabled to a given item or not
   void setApplyColorToBranchEnabledForItem(vtkIdType itemID, bool enabled);
 
+  /// Update show empty folders context menu item visibility and checked state.
+  /// The update needs to happen in more than one place, which is handled by this method.
+  void updateShowEmptyFoldersAction();
+
 protected:
   QScopedPointer<qSlicerSubjectHierarchyFolderPluginPrivate> d_ptr;
 

Modules/Loadable/SubjectHierarchy/Widgets/qSlicerSubjectHierarchyPluginHandler.cxx

@@ -486,7 +486,7 @@ void qSlicerSubjectHierarchyPluginHandler::setCurrentItem(vtkIdType itemID)
 }
 
 //-----------------------------------------------------------------------------
-vtkIdType qSlicerSubjectHierarchyPluginHandler::currentItem()
+vtkIdType qSlicerSubjectHierarchyPluginHandler::currentItem()const
 {
   if (this->m_CurrentItems.size() != 1)
     {
@@ -502,13 +502,13 @@ void qSlicerSubjectHierarchyPluginHandler::setCurrentItems(QList<vtkIdType> item
 }
 
 //-----------------------------------------------------------------------------
-QList<vtkIdType> qSlicerSubjectHierarchyPluginHandler::currentItems()
+QList<vtkIdType> qSlicerSubjectHierarchyPluginHandler::currentItems()const
 {
   return this->m_CurrentItems;
 }
 
 //------------------------------------------------------------------------------
-void qSlicerSubjectHierarchyPluginHandler::currentItems(vtkIdList* selectedItems)
+void qSlicerSubjectHierarchyPluginHandler::currentItems(vtkIdList* selectedItems)const
 {
   if (!selectedItems)
     {
@@ -522,6 +522,18 @@ void qSlicerSubjectHierarchyPluginHandler::currentItems(vtkIdList* selectedItems
     }
 }
 
+//-----------------------------------------------------------------------------
+void qSlicerSubjectHierarchyPluginHandler::setCurrentTreeView(qMRMLSubjectHierarchyTreeView* treeView)
+{
+  this->m_CurrentTreeView = treeView;
+}
+
+//-----------------------------------------------------------------------------
+qMRMLSubjectHierarchyTreeView* qSlicerSubjectHierarchyPluginHandler::currentTreeView()const
+{
+  return this->m_CurrentTreeView;
+}
+
 //-----------------------------------------------------------------------------
 bool qSlicerSubjectHierarchyPluginHandler::autoDeleteSubjectHierarchyChildren()const
 {

Modules/Loadable/SubjectHierarchy/Widgets/qSlicerSubjectHierarchyPluginHandler.h

@@ -42,6 +42,7 @@
 
 class vtkMRMLScene;
 class vtkCallbackCommand;
+class qMRMLSubjectHierarchyTreeView;
 class qSlicerSubjectHierarchyPluginLogic;
 class qSlicerSubjectHierarchyAbstractPlugin;
 class qSlicerSubjectHierarchyDefaultPlugin;
@@ -106,7 +107,7 @@ class Q_SLICER_MODULE_SUBJECTHIERARCHY_WIDGETS_EXPORT qSlicerSubjectHierarchyPlu
   /// IMPORTANT NOTE: This function is solely used for plugin-provided context menus. This is NOT to be used for getting the
   ///                 selected item of individual widgets (tree views, comboboxes).
   /// \return Current item if only one is selected, otherwise INVALID_ITEM_ID
-  Q_INVOKABLE vtkIdType currentItem();
+  Q_INVOKABLE vtkIdType currentItem()const;
 
   /// Set current subject hierarchy items in case of multi-selection
   /// IMPORTANT NOTE: This function will not change the selection in individual widgets (tree views, comboboxes). This is
@@ -116,8 +117,14 @@ class Q_SLICER_MODULE_SUBJECTHIERARCHY_WIDGETS_EXPORT qSlicerSubjectHierarchyPlu
   /// Get current subject hierarchy items in case of multi-selection
   /// IMPORTANT NOTE: This function is solely used for plugin-provided context menus. This is NOT to be used for getting the
   ///                 selected items of individual widgets (tree views, comboboxes).
-  Q_INVOKABLE QList<vtkIdType> currentItems();
-  Q_INVOKABLE void currentItems(vtkIdList* selectedItems);
+  Q_INVOKABLE QList<vtkIdType> currentItems()const;
+  Q_INVOKABLE void currentItems(vtkIdList* selectedItems)const;
+
+  /// Set current tree view. The tree view where context menu was requested sets this.
+  /// It allows accessing the tree view the user is using.
+  Q_INVOKABLE void setCurrentTreeView(qMRMLSubjectHierarchyTreeView* treeView);
+  /// Get current tree view.
+  Q_INVOKABLE qMRMLSubjectHierarchyTreeView* currentTreeView()const;
 
   Q_INVOKABLE bool autoDeleteSubjectHierarchyChildren()const;
   Q_INVOKABLE void setAutoDeleteSubjectHierarchyChildren(bool flag);
@@ -217,6 +224,9 @@ class Q_SLICER_MODULE_SUBJECTHIERARCHY_WIDGETS_EXPORT qSlicerSubjectHierarchyPlu
   /// (selected items in the tree view e.g. for context menu request)
   QList<vtkIdType> m_CurrentItems;
 
+  /// Most recently right-clicked subject hierarchy tree view
+  qMRMLSubjectHierarchyTreeView* m_CurrentTreeView{nullptr};
+
   /// MRML scene (to get new subject hierarchy node if the stored one is deleted)
   vtkWeakPointer<vtkMRMLScene> m_MRMLScene;