Fixed broken context search and hide empty categories from filter.

Searching through the context menu was broken after 883e8a0 due to a
mis-comparison on node data that is never inserted. This has been fixed
by correctly comparing QTreeWidgetItem::text.

Furthermore, the filtering system has been changed to hide empty
categories, showing only those that are relevant (contain matching
nodes).

Signed-off-by: Finn Rayment <finn@rayment.fr>

Author: rayment

src/DataFlowGraphicsScene.cpp

@@ -140,13 +140,24 @@ createSceneMenu(QPointF const scenePos)
   connect(txtBox, &QLineEdit::textChanged,
           [treeView](const QString& text)
           {
+            QTreeWidgetItemIterator categoryIt(treeView, QTreeWidgetItemIterator::HasChildren);
+            while (*categoryIt)
+              (*categoryIt++)->setHidden(true);
             QTreeWidgetItemIterator it(treeView, QTreeWidgetItemIterator::NoChildren);
             while (*it)
             {
-              auto modelName = (*it)->data(0, Qt::UserRole).toString();
+              auto modelName = (*it)->text(0);
               const bool match = (modelName.contains(text, Qt::CaseInsensitive));
               (*it)->setHidden(!match);
-
+              if (match)
+              {
+                QTreeWidgetItem *parent = (*it)->parent();
+                while (parent)
+                {
+                  parent->setHidden(false);
+                  parent = parent->parent();
+                }
+              }
               ++it;
             }
           });