Merge pull request #997 from ispyisail/revive/659-preserve-links

Preserve master/slave links when pasting or duplicating a folio

sources/diagramcommands.cpp

@@ -77,6 +77,23 @@ void PasteDiagramCommand::redo()
 	{
 		first_redo = false;
 
+		//Resolve a linked master/slave pair pasted together (bugtracker
+		//#607) before anything below renews their uuids: at this exact
+		//moment a pasted element's tmp_uuids_link still holds its
+		//source's original partner uuid, which still equals the
+		//not-yet-renewed uuid of that partner's own pasted copy if it
+		//was carried along in the same batch. Scoped to this batch only
+		//(not a project-wide search), so a pair pasted together links to
+		//each other and not to an original element left elsewhere that
+		//happens to still carry that same soon-to-be-replaced uuid. If
+		//only one half of a linked group was pasted, its link entry
+		//simply finds no match here and is dropped -- same "leave it
+		//unlinked" outcome as always.
+		const QList <Element *> elmts_list = content.m_elements;
+		for (Element *e : elmts_list) {
+			e->initLink(elmts_list);
+		}
+
 		//make new uuid for every pasted conductor, because old uuid are
 		//the uuid of the copied conductor
 		const QList <Conductor *> all_pasted_conductors = content.conductors();
@@ -85,7 +102,6 @@ void PasteDiagramCommand::redo()
 		}
 
 		//this is the first paste, we do some actions for the new element
-		const QList <Element *> elmts_list = content.m_elements;
 		for (Element *e : elmts_list)
 		{
 			//make new uuid, because old uuid are the uuid of the copied element

sources/elementspanelwidget.cpp

@@ -674,6 +674,27 @@ void ElementsPanelWidget::duplicateDiagram()
 		bool erase_labels = settings.value(
 			"diagramcommands/erase-label-on-copy", true).toBool();
 
+		// Resolve a linked pair duplicated together against each other
+		// (bugtracker #607) before the loop below renews their uuids or
+		// clears their pending links: at this exact moment a copy's
+		// tmp_uuids_link still holds its source's original partner
+		// uuid, which still equals the not-yet-renewed uuid of that
+		// partner's own copy if both were duplicated together. Scoped
+		// to this diagram's own copies, not a project-wide search, so
+		// this never links back to the source elements the copies were
+		// made from -- if only one half of a linked pair is here, its
+		// link entry simply finds no match and is dropped, same as
+		// clearPendingLinks() used to do unconditionally for every copy.
+		QList<Element *> new_elements;
+		for (QGraphicsItem *item : new_diagram->items()) {
+			if (Element *elmt = dynamic_cast<Element *>(item)) {
+				new_elements << elmt;
+			}
+		}
+		for (Element *elmt : new_elements) {
+			elmt->initLink(new_elements);
+		}
+
 		for (QGraphicsItem *item : new_diagram->items()) {
 			if (Element *elmt = dynamic_cast<Element *>(item)) {
 				// The XML round-trip kept the source elements' uuids. Give the
@@ -695,9 +716,9 @@ void ElementsPanelWidget::duplicateDiagram()
 					new_diagram->restoreText(elmt);
 				}
 
-				// Clear pending links so copies don't link back to
-				// the source elements via stale UUIDs.
-				elmt->clearPendingLinks();
+				// initLink() above already cleared tmp_uuids_link for
+				// every copy, matched or not -- nothing left here that
+				// could link back to a stale source uuid.
 
 				// Clean up copied element data:
 				// 1. Slaves always lose label/formula/comment/location

sources/qetgraphicsitem/element.cpp

@@ -1386,6 +1386,33 @@ void Element::initLink(QETProject *prj)
 	tmp_uuids_link.clear();
 }
 
+/**
+	@brief Element::initLink
+	Overload resolving tmp_uuids_link against @p candidates instead of a
+	project-wide ElementProvider search -- see the header comment for
+	why the search has to be scoped this way right after a paste or
+	folio-duplication XML round-trip, before uuids are renewed.
+	@param candidates the elements to search for a link partner in
+*/
+void Element::initLink(const QList<Element *> &candidates)
+{
+		// if nothing to link return now
+	if (tmp_uuids_link.isEmpty()) return;
+
+	for (int i = 0; i < tmp_uuids_link.size(); ++i) {
+		for (Element *elmt : candidates) {
+			if (elmt->uuid() == tmp_uuids_link[i].uuid) {
+				elmt->linkToElement(this);
+				if (tmp_uuids_link[i].group_index >= 0) {
+					m_group_index_map[elmt] = tmp_uuids_link[i].group_index;
+				}
+				break;
+			}
+		}
+	}
+	tmp_uuids_link.clear();
+}
+
 /**
  * @brief Element::linkTypeToString
  * \deprecated use instead ElementData::typeToString

sources/qetgraphicsitem/element.h

@@ -207,6 +207,25 @@ class Element : public QetGraphicsItem
 		virtual void unlinkAllElements() {}
 		virtual void unlinkElement(Element *) {}
 		virtual void initLink(QETProject *);
+			/**
+				Resolve tmp_uuids_link against a caller-supplied candidate
+				list instead of a project-wide search (bugtracker #607).
+				Used right after an XML round-trip (paste, folio
+				duplication) and before the pasted/duplicated elements'
+				uuids are renewed: at that moment a copy's tmp_uuids_link
+				still holds its source's original partner uuid, which
+				still matches the not-yet-renewed uuid of that partner's
+				own copy if it was carried along in the same batch.
+				Resolving only within @p candidates -- not the whole
+				project -- is what stops a linked pair pasted together
+				from matching an original element left elsewhere that
+				happens to still carry that same soon-to-be-replaced
+				uuid. If only one half of a linked group is in
+				@p candidates, its entry finds no match and is dropped,
+				same as initLink(QETProject *) leaving an unresolvable
+				link unlinked.
+			*/
+		void initLink(const QList<Element *> &candidates);
 		QList<Element *> linkedElements ();
 
 		int groupIndexForElement(Element *elmt) const;