Let search results be dragged onto a folio like the tree

While a collection search is active the tree is replaced by the flat
ranked list, and that list had no drag support: dragging a result only
moved the selection. Anyone used to searching and then dragging lost the
drag as soon as they typed.

The tree's drag is moved into a static ElementsTreeView::execElementDrag()
taking the source widget, and the results list uses it from the path each
row already carries, so the drag content and pixmap are the same.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G2d2Zi8BfrYRPX88zhaoFG

sources/ElementsCollection/elementscollectionwidget.cpp

@@ -55,6 +55,32 @@
 #include <QStatusBar>
 #include <QLineEdit>
 
+namespace {
+/**
+	@brief The SearchResultsView class
+	The flat list of search results. Rows are not backed by the collection
+	model, so the drag is built here from the path each row carries, with
+	the same content and pixmap as a drag from the tree.
+*/
+class SearchResultsView : public QListView
+{
+	public:
+		using QListView::QListView;
+
+	protected:
+		void startDrag(Qt::DropActions supportedActions) override
+		{
+			const QString path =
+				currentIndex().data(Qt::UserRole + 2).toString();
+			if (path.isEmpty()) {
+				QListView::startDrag(supportedActions);
+				return;
+			}
+			ElementsTreeView::execElementDrag(this, ElementsLocation(path));
+		}
+};
+}
+
 /**
 	@brief ElementsCollectionWidget::ElementsCollectionWidget
 	Default constructor.
@@ -230,8 +256,9 @@ void ElementsCollectionWidget::setUpWidget()
 		//ranked list instead, and takes the tab widget's place while a search
 		//is active.
 	m_search_model = new QStandardItemModel(this);
-	m_search_results = new QListView(this);
+	m_search_results = new SearchResultsView(this);
 	m_search_results->setModel(m_search_model);
+	m_search_results->setDragDropMode(QAbstractItemView::DragOnly);
 	m_search_results->setIconSize(QSize(50, 50));
 	m_search_results->setUniformItemSizes(false);
 	m_search_results->setVerticalScrollMode(QAbstractItemView::ScrollPerPixel);

sources/ElementsCollection/elementstreeview.cpp

@@ -82,13 +82,27 @@ void ElementsTreeView::startDrag(Qt::DropActions supportedActions)
 	@param location : location to use for create the content of the QDrag
 */
 void ElementsTreeView::startElementDrag(const ElementsLocation &location)
+{
+	execElementDrag(this, location);
+}
+
+/**
+	@brief ElementsTreeView::execElementDrag
+	Build and run the QDrag for @a location, from @a source.
+	Static so that a view which is not an ElementsTreeView -- the flat list
+	of search results -- starts exactly the same drag as the tree.
+	@param source : the widget the drag starts from
+	@param location : location to use for create the content of the QDrag
+*/
+void ElementsTreeView::execElementDrag(QWidget *source,
+				       const ElementsLocation &location)
 {
 	if (! location.exist()) return;
 
 #if QT_VERSION < QT_VERSION_CHECK(6, 2, 0)
-	QDrag* drag = new QDrag(this);
+	QDrag* drag = new QDrag(source);
 #else
-	QScopedPointer<QDrag> drag(new QDrag(this));
+	QScopedPointer<QDrag> drag(new QDrag(source));
 #endif
 
 	QString location_str = location.toString();
@@ -209,7 +223,7 @@ void ElementsTreeView::startElementDrag(const ElementsLocation &location)
 			&elmt_creation_state));
 		if (elmt_creation_state) { return; }
 
-		QPixmap elmt_pixmap(QET::Palette::forPalette(temp_elmt->pixmap(), palette()));
+		QPixmap elmt_pixmap(QET::Palette::forPalette(temp_elmt->pixmap(), source->palette()));
 		QPoint elmt_hotspot(temp_elmt->hotspot());
 
 			//Adjust the size of the pixmap if he is too big

sources/ElementsCollection/elementstreeview.h

@@ -32,6 +32,8 @@ class ElementsTreeView : public QTreeView
 {
 	public:
 		ElementsTreeView(QWidget *parent = nullptr);
+		static void execElementDrag(QWidget *source,
+					    const ElementsLocation &location);
 
 	protected:
 		void startDrag(Qt::DropActions supportedActions) override;