Rotate a selected group as one piece

Discussion #1070 proposed that rotate, like move, copy and delete, works on
the whole group once one of its items is clicked. Rotate (Space) turned
each member on its own spot instead, so rotating a group pulled it apart:
two grouped texts side by side ended up each turned in place, no longer
side by side.

When the selection is exactly one whole group -- wires aside, which follow
their symbols -- Rotate now turns it as one piece around its centre, as
"Pivoter le groupe" (Shift+Space) already does
(ItemGroups::soleWholeGroup()). Any other selection, including a single
member picked out of its group, rotates as before.

In the GUI, on two grouped texts selected by one click: Space on master
leaves both where they were, turned; here it gives exactly what
Shift+Space gives on both (both texts swung around the group's centre).
tst_itemgroups: 4 new checks; without the whole-group condition, a
picked member counts as a group and fails. ctest 24/24.

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

sources/itemgroups.cpp

@@ -122,3 +122,34 @@ bool ItemGroups::completeSelection(QGraphicsScene *scene,
 	}
 	return changed;
 }
+
+/**
+	@return the group @a selected is exactly, whole -- every item in it
+	belongs to that group and every member of the group is in it -- or a null
+	uuid. Rotating such a selection turns the group as one piece rather than
+	each member in place (discussion #1070). A member picked out on its own
+	is not a whole group, and turns in place.
+	@param selected : the selected items that can be members (the caller
+	leaves out wires, which follow their symbols)
+*/
+QUuid ItemGroups::soleWholeGroup(const QList<QGraphicsItem *> &selected)
+{
+	if (selected.isEmpty() || !selected.first()->scene()) {
+		return QUuid();
+	}
+	const QUuid group = groupOf(selected.first());
+	if (group.isNull()) {
+		return QUuid();
+	}
+	for (QGraphicsItem *item : selected) {
+		if (groupOf(item) != group) {
+			return QUuid();
+		}
+	}
+	for (QGraphicsItem *item : selected.first()->scene()->items()) {
+		if (groupOf(item) == group && !item->isSelected()) {
+			return QUuid();
+		}
+	}
+	return group;
+}

sources/itemgroups.h

@@ -55,6 +55,8 @@ namespace ItemGroups
 	bool completeSelection(QGraphicsScene *scene,
 						   const QList<QGraphicsItem *> &previous,
 						   bool toggling);
+
+	QUuid soleWholeGroup(const QList<QGraphicsItem *> &selected);
 }
 
 #endif // ITEMGROUPS_H

sources/qetdiagrameditor.cpp

@@ -25,6 +25,7 @@
 #include "ElementsCollection/elementpickerpopup.h"
 #include "shortcutbarsettings.h"
 #include "qetgraphicsitem/conductor.h"
+#include "itemgroups.h"
 #include "commandsearchpopup.h"
 #include "QWidgetAnimation/qwidgetanimation.h"
 #include "autoNum/ui/autonumberingdockwidget.h"
@@ -2078,7 +2079,17 @@ void QETDiagramEditor::selectionGroupTriggered(QAction *action)
         }
 	else if (value == "rotate_selection")
 	{
-		RotateSelectionCommand *c = new RotateSelectionCommand(diagram);
+			//A selection that is exactly one whole group turns as one piece,
+			//as "Pivoter le groupe" does, rather than each member in place
+			//(discussion #1070). Wires follow their symbols either way.
+		QList<QGraphicsItem *> members;
+		for (QGraphicsItem *item : diagram->selectedItems()) {
+			if (item->type() != Conductor::Type) {
+				members << item;
+			}
+		}
+		const bool whole_group = !ItemGroups::soleWholeGroup(members).isNull();
+		RotateSelectionCommand *c = new RotateSelectionCommand(diagram, 90, nullptr, whole_group);
 		if(c->isValid())
 			diagram->undoStack().push(c);
 	}

tests/qttest/tst_itemgroups.cpp

@@ -136,6 +136,34 @@ private slots:
 		ItemGroups::setGroup(a, QUuid());
 		QVERIFY(ItemGroups::groupOf(a).isNull());
 	}
+
+	// Rotate turns a selection that is exactly one whole group as one piece.
+	void aWholeGroupAloneIsASoleWholeGroup()
+	{
+		select({a, b});
+		QCOMPARE(ItemGroups::soleWholeGroup(selection()), g1);
+	}
+
+	void aPickedMemberIsNotAWholeGroup()
+	{
+		select({a});
+		QVERIFY(ItemGroups::soleWholeGroup(selection()).isNull());
+	}
+
+	void aGroupWithOtherItemsIsNotASoleGroup()
+	{
+		select({a, b, c});
+		QVERIFY(ItemGroups::soleWholeGroup(selection()).isNull());
+		select({a, b, d, e});
+		QVERIFY(ItemGroups::soleWholeGroup(selection()).isNull());
+	}
+
+	void ungroupedItemsAreNotAGroup()
+	{
+		select({c});
+		QVERIFY(ItemGroups::soleWholeGroup(selection()).isNull());
+		QVERIFY(ItemGroups::soleWholeGroup({}).isNull());
+	}
 };
 
 QTEST_MAIN(tst_itemgroups)