Reattach wires to a terminal that moved a little since the project was saved

A project saves, for every placed symbol, where each terminal docked, its
orientation and its number. When the symbol's definition is replaced by one
whose terminal sits a few units elsewhere, wires were matched by exact
position and so were dropped on the next open: legacy wires by Terminal::
fromXml(), uuid wires by the uuid derived from the terminal's new place.

Element::fromXml() now pairs each saved terminal that nothing matched
exactly with the live terminal of the same orientation whose docking point
is within 5 units in x and y, only when each is the other's only candidate.
A pair registers the saved number, and the uuid derived from the old place,
which Diagram::findTerminals() checks after the derived uuid of the current
place. Wire ends reattached this way are counted and logged once per folio.

tst_movedterminals covers a move of 3 and 5 units (number and derived
uuid), 6 units, two candidates, and an unmoved terminal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

sources/qetgraphicsitem/element.cpp

@@ -19,6 +19,7 @@
 #include "../qetapp.h"
 #include "../qetproject.h"
 #include "../dataBase/projectdatabase.h"
+#include "../ElementsCollection/terminaluuids.h"
 #include "../PropertiesEditor/propertieseditordialog.h"
 #include "../autoNum/assignvariables.h"
 #include "../autoNum/elementautonumschemecommand.h"
@@ -972,6 +973,107 @@ bool Element::valideXml(QDomElement &e)
 	return(true);
 }
 
+/**
+	@brief Element::matchMovedTerminals
+	Pair the saved terminals that no live terminal matched exactly with the
+	live terminals that moved a little: the definition of the symbol was
+	replaced or redrawn since the project was saved. A saved record gives
+	the old docking point and orientation of its terminal, so it is paired
+	with a live terminal of the same orientation whose docking point is
+	within moved_terminal_reach in x and y, when each is the only candidate
+	of the other. Anything less clear stays unmatched, as before.
+
+	A pair registers the record's legacy id, and the uuid TerminalUuids
+	derived for the terminal at its old place, so that a wire naming either
+	reattaches (see Diagram::findTerminals()).
+	@param records : the saved terminals of this symbol
+	@param matched_records : indexes in records already matched
+	@param matched_terminals : the live terminals already matched
+	@param id_adr : receives the legacy id of each pair
+*/
+void Element::matchMovedTerminals(const QList<QDomElement> &records,
+								  const QSet<int> &matched_records,
+								  const QSet<Terminal *> &matched_terminals,
+								  QHash<int, Terminal *> &id_adr)
+{
+	if (matched_records.size() == records.size()) return;
+
+	const auto dock_of = [](const QDomElement &r) {
+		return QPointF(r.attribute(QStringLiteral("x")).toDouble(),
+					   r.attribute(QStringLiteral("y")).toDouble());
+	};
+	const auto orientation_of = [](const QDomElement &r) {
+		return r.attribute(QStringLiteral("orientation")).toInt();
+	};
+
+	QHash<int, QList<Terminal *>> candidates;  // record -> live terminals in reach
+	QHash<Terminal *, QList<int>> claimants;   // live terminal -> records in reach
+	for (int i = 0; i < records.size(); ++i) {
+		if (matched_records.contains(i)) continue;
+		const QPointF dock = dock_of(records.at(i));
+		for (Terminal *t : std::as_const(m_terminals)) {
+			if (matched_terminals.contains(t)) continue;
+			if (static_cast<int>(t->orientation()) != orientation_of(records.at(i))) continue;
+			if (qAbs(t->dock_elmt_.x() - dock.x()) > moved_terminal_reach
+				|| qAbs(t->dock_elmt_.y() - dock.y()) > moved_terminal_reach) continue;
+			candidates[i] << t;
+			claimants[t] << i;
+		}
+	}
+
+	for (auto it = candidates.constBegin(); it != candidates.constEnd(); ++it) {
+		Terminal *t = it.value().value(0);
+		if (it.value().size() != 1 || claimants.value(t).size() != 1) continue;
+		const QDomElement &record = records.at(it.key());
+		const QPointF dock = dock_of(record);
+
+			//The old place of the terminal: its docking point less the
+			//stub that Terminal::init() added
+		QPointF old_pos = dock;
+		switch (orientation_of(record)) {
+			case Qet::North: old_pos -= QPointF(0, Terminal::terminalSize);  break;
+			case Qet::East : old_pos -= QPointF(-Terminal::terminalSize, 0); break;
+			case Qet::West : old_pos -= QPointF(Terminal::terminalSize, 0);  break;
+			case Qet::South: old_pos -= QPointF(0, -Terminal::terminalSize); break;
+		}
+			//The rank among the records at the same place, as the project
+			//counted it when it gave the terminals their uuids
+		int rank = 0;
+		for (int j = 0; j < it.key(); ++j) {
+			const QPointF other = dock_of(records.at(j));
+			if (orientation_of(records.at(j)) == orientation_of(record)
+				&& qAbs(other.x() - dock.x()) < 1e-6
+				&& qAbs(other.y() - dock.y()) < 1e-6)
+				++rank;
+		}
+
+		id_adr.insert(record.attribute(QStringLiteral("id")).toInt(), t);
+		m_old_place_terminals.insert(TerminalUuids::derived(old_pos.x(), old_pos.y(),
+															orientation_of(record), rank), t);
+		m_moved_terminals << t;
+	}
+}
+
+/**
+	@return the terminal that was paired with the saved terminal whose uuid
+	derived from its old place is @p old_place_uuid, if any
+	@see matchMovedTerminals()
+*/
+Terminal *Element::terminalFromOldPlace(const QUuid &old_place_uuid) const
+{
+	return m_old_place_terminals.value(old_place_uuid, nullptr);
+}
+
+/**
+	@return true if @p terminal was paired with a saved terminal at another
+	place than its own
+	@see matchMovedTerminals()
+*/
+bool Element::terminalWasMoved(const Terminal *terminal) const
+{
+	return m_moved_terminals.contains(const_cast<Terminal *>(terminal));
+}
+
 /**
 	@brief Element::fromXml
 	Import the parameters of this element from a xml document.
@@ -999,22 +1101,28 @@ bool Element::fromXml(QDomElement &e,
 	}
 
 	QHash<int, Terminal *> priv_id_adr;
+	QSet<Terminal *> matched_terminals;
+	QSet<int> matched_records;
 
 	for (auto *qgi : childItems())
 	{
 		if (auto terminal_ = qgraphicsitem_cast<Terminal *>(qgi))
 		{
-			for(auto qde : liste_terminals)
+			for (int i = 0; i < liste_terminals.size(); ++i)
 			{
+				QDomElement qde = liste_terminals.at(i);
 				if (terminal_ -> fromXml(qde))
 				{
 					priv_id_adr.insert(qde.attribute(QStringLiteral("id")).toInt(),
 									   terminal_);
+					matched_terminals << terminal_;
+					matched_records << i;
 				}
 			}
 		}
 	}
 
+	matchMovedTerminals(liste_terminals, matched_records, matched_terminals, priv_id_adr);
 
 		//Check that associated id/address doesn't conflict with table_id_adr
 	for(auto found_id : priv_id_adr.keys())