Add "rotate group" to actually rotate a selection as a whole

RotateSelectionCommand's existing "Pivoter" action (Space) only ever
bumps each selected item's own rotation property -- QGraphicsItem's
setRotation() spins an item around its own local origin and never
touches pos(). Select three elements arranged in a row and rotate:
each spins 90 degrees individually, but the row stays a row. That's
"rotate each item," not "rotate the group."

Add a rotate_as_group parameter to RotateSelectionCommand (default
false, so the existing action and its one call site are unchanged).
When set, it computes a shared pivot once -- the bounding-box center
of the whole selection -- and queues a second, parallel "pos"
QPropertyUndoCommand alongside the existing "rotation" one, rotating
each item's position around that pivot by the same angle.

Scoped the position change to Element/IndependentTextItem/
DiagramImageItem only: these are the only selectable types with
scene-space pos(). ConductorTextItem, DynamicElementTextItem and
ElementTextItemGroup are all parent-relative children (confirmed by
reading their constructors), so when their owning Element is also
selected and gets its own pos() rotated, they're carried along for
free by Qt's normal parent/child transform propagation -- exactly
what the existing "skip rotation if parent is also selected" guard
already assumes for those three cases.

Exposed as a new, separate action ("Pivoter le groupe", Shift+Space)
next to the existing one rather than changing Space's behavior, since
some workflows may rely on the current per-item rotation.

sources/qetdiagrameditor.cpp

@@ -628,6 +628,7 @@ void QETDiagramEditor::setUpActions()
 		//Selections Actions (related to a selected item)
 	m_delete_selection     = m_selection_actions_group.addAction( QET::Icons::EditDelete,        tr("Supprimer")                 );
 	m_rotate_selection     = m_selection_actions_group.addAction( QET::Icons::TransformRotate,   tr("Pivoter")                   );
+	m_rotate_group_selection = m_selection_actions_group.addAction( QET::Icons::TransformRotate, tr("Pivoter le groupe")         );
 	m_rotate_texts         = m_selection_actions_group.addAction( QET::Icons::ObjectRotateRight, tr("Orienter les textes")       );
 	m_find_element         = m_selection_actions_group.addAction( QET::Icons::ZoomDraw,          tr("Retrouver dans le panel")   );
 	m_edit_selection       = m_selection_actions_group.addAction( QET::Icons::ElementEdit,       tr("Éditer l'item sélectionné") );
@@ -635,16 +636,19 @@ void QETDiagramEditor::setUpActions()
 
 	ShortcutManager::instance().registerAction(m_delete_selection, "diagrameditor.delete_selection", tr("Éditeur de schémas"), Qt::Key_Delete);
 	ShortcutManager::instance().registerAction(m_rotate_selection, "diagrameditor.rotate_selection", tr("Éditeur de schémas"), Qt::Key_Space);
+	ShortcutManager::instance().registerAction(m_rotate_group_selection, "diagrameditor.rotate_group_selection", tr("Éditeur de schémas"), Qt::SHIFT | Qt::Key_Space);
 	ShortcutManager::instance().registerAction(m_rotate_texts, "diagrameditor.rotate_texts", tr("Éditeur de schémas"), Qt::CTRL | Qt::Key_Space);
 	ShortcutManager::instance().registerAction(m_edit_selection, "diagrameditor.edit_selection", tr("Éditeur de schémas"), Qt::CTRL | Qt::Key_E);
 
 	m_delete_selection->setStatusTip( tr("Enlève les éléments sélectionnés du folio", "status bar tip"));
 	m_rotate_selection->setStatusTip( tr("Pivote les éléments et textes sélectionnés", "status bar tip"));
+	m_rotate_group_selection->setStatusTip( tr("Pivote la sélection comme un groupe autour de son centre, au lieu de chaque élément sur place", "status bar tip"));
 	m_rotate_texts    ->setStatusTip( tr("Pivote les textes sélectionnés à un angle précis", "status bar tip"));
 	m_find_element    ->setStatusTip( tr("Retrouve l'élément sélectionné dans le panel", "status bar tip"));
 
 	m_delete_selection    ->setData("delete_selection");
 	m_rotate_selection    ->setData("rotate_selection");
+	m_rotate_group_selection->setData("rotate_group_selection");
 	m_rotate_texts        ->setData("rotate_selected_text");
 	m_find_element        ->setData("find_selected_element");
 	m_edit_selection      ->setData("edit_selected_element");
@@ -1601,6 +1605,12 @@ void QETDiagramEditor::selectionGroupTriggered(QAction *action)
 		if(c->isValid())
 			diagram->undoStack().push(c);
 	}
+	else if (value == "rotate_group_selection")
+	{
+		RotateSelectionCommand *c = new RotateSelectionCommand(diagram, 90, nullptr, true);
+		if(c->isValid())
+			diagram->undoStack().push(c);
+	}
 	else if (value == "rotate_selected_text")
 		diagram->undoStack().push(new RotateTextsCommand(diagram));
 	else if (value == "find_selected_element" && currentElement())
@@ -1735,6 +1745,7 @@ void QETDiagramEditor::slot_updateComplexActions()
 			    << m_copy
 			    << m_delete_selection
 			    << m_rotate_selection
+			    << m_rotate_group_selection
 			    << m_edit_selection
 			    << m_group_selected_texts;
 		for(QAction *action : action_list)
@@ -1763,6 +1774,7 @@ void QETDiagramEditor::slot_updateComplexActions()
 	m_copy             -> setEnabled(copiable_items);
 	m_delete_selection -> setEnabled(!ro && deletable_items);
 	m_rotate_selection -> setEnabled(!ro && diagram_->canRotateSelection());
+	m_rotate_group_selection -> setEnabled(!ro && diagram_->canRotateSelection());
 
 		//Action that need selected texts or texts group
 	QList<DiagramTextItem *> texts = DiagramContent(diagram_).selectedTexts();

sources/qetdiagrameditor.h

@@ -216,6 +216,7 @@ class QETDiagramEditor : public QETMainWindow
 		*m_edit_selection,		///< To edit selected item
 		*m_delete_selection,		///< Delete selection
 		*m_rotate_selection,		///< Rotate selected elements and text items by 90 degrees
+		*m_rotate_group_selection = nullptr, ///< Rotate the selection as a whole around its shared center, instead of each item in place
 		*m_rotate_texts,		///< Direct selected text items to a specific angle
 		*m_find_element,		///< Find the selected element in the panel
 		*m_group_selected_texts = nullptr,

sources/undocommand/rotateselectioncommand.cpp

@@ -29,21 +29,37 @@
 #include "../qetgraphicsitem/independenttextitem.h"
 
 #include <QGraphicsItem>
+#include <QtMath>
 
-RotateSelectionCommand::RotateSelectionCommand(Diagram *diagram, qreal angle, QUndoCommand *parent) :
+RotateSelectionCommand::RotateSelectionCommand(Diagram *diagram, qreal angle, QUndoCommand *parent, bool rotate_as_group) :
 QUndoCommand(parent),
 m_diagram(diagram)
 {
-	setText(QObject::tr("Pivoter la selection"));
+	setText(rotate_as_group ? QObject::tr("Pivoter le groupe") : QObject::tr("Pivoter la selection"));
 
 	if(!m_diagram->isReadOnly())
 	{
+			//Shared pivot for group rotation: the bounding-box center of
+			//everything selected, computed once up front from the
+			//selection as a whole (not just the items that end up being
+			//individually repositioned below).
+		QPointF pivot;
+		if (rotate_as_group)
+		{
+			QRectF bounding_rect;
+			for (QGraphicsItem *item : m_diagram->selectedItems())
+				bounding_rect |= item->sceneBoundingRect();
+			pivot = bounding_rect.center();
+		}
+
 		for (QGraphicsItem *item : m_diagram->selectedItems())
 		{
 			switch (item->type())
 			{
 				case Element::Type:
 					m_undo << new QPropertyUndoCommand(item->toGraphicsObject(), "rotation", QVariant(item->rotation()), QVariant(item->rotation()+angle), this);
+					if (rotate_as_group)
+						addGroupPositionUndo(item, pivot, angle);
 					break;
 				case ConductorTextItem::Type:
 				{
@@ -53,9 +69,19 @@ m_diagram(diagram)
 					break;
 				case IndependentTextItem::Type:
 					m_undo << new QPropertyUndoCommand(item->toGraphicsObject(), "rotation", QVariant(item->rotation()), QVariant(item->rotation()+angle), this);
+					if (rotate_as_group)
+						addGroupPositionUndo(item, pivot, angle);
 					break;
 				case DynamicElementTextItem::Type:
 				{
+						//No pos() undo here even in group mode: this item is
+						//only rotated in place when its parent Element isn't
+						//also selected (guard below), and its pos() is
+						//parent-local, not scene coordinates -- when the
+						//parent Element *is* selected and gets its own pos()
+						//rotated around the shared pivot above, this child
+						//text item is carried along for free by Qt's normal
+						//parent/child transform propagation.
 					if(item->parentItem() && !item->parentItem()->isSelected())
 						m_undo << new QPropertyUndoCommand(item->toGraphicsObject(), "rotation", QVariant(item->rotation()), QVariant(item->rotation()+angle), this);
 				}
@@ -69,6 +95,8 @@ m_diagram(diagram)
 					break;
 				case DiagramImageItem::Type:
 					m_undo << new QPropertyUndoCommand(item->toGraphicsObject(), "rotation", QVariant(item->rotation()), QVariant(item->rotation()+angle), this);
+					if (rotate_as_group)
+						addGroupPositionUndo(item, pivot, angle);
 					break;
 				default:
 					break;
@@ -80,6 +108,31 @@ m_diagram(diagram)
 	}
 }
 
+/**
+	@brief RotateSelectionCommand::addGroupPositionUndo
+	Queue a "pos" QPropertyUndoCommand that rotates @a item's position
+	around @a pivot by @a angle degrees (Qt's clockwise-positive
+	convention, matching QGraphicsItem::setRotation() so a group
+	rotation turns the same direction as each item's own spin).
+	Only meaningful for items whose pos() is in scene coordinates
+	(Element, IndependentTextItem, DiagramImageItem) -- never call this
+	for a child item positioned relative to its own parent.
+	@param item : item to reposition, its own rotation undo already queued
+	@param pivot : shared pivot point, in scene coordinates
+	@param angle : rotation angle in degrees
+*/
+void RotateSelectionCommand::addGroupPositionUndo(QGraphicsItem *item, const QPointF &pivot, qreal angle)
+{
+	const QPointF old_pos = item->pos();
+	const qreal radians = qDegreesToRadians(angle);
+	const QPointF delta = old_pos - pivot;
+	const QPointF new_pos(
+		pivot.x() + delta.x() * qCos(radians) - delta.y() * qSin(radians),
+		pivot.y() + delta.x() * qSin(radians) + delta.y() * qCos(radians)
+	);
+	m_undo << new QPropertyUndoCommand(item->toGraphicsObject(), "pos", QVariant(old_pos), QVariant(new_pos), this);
+}
+
 /**
 	@brief RotateSelectionCommand::undo
 */

sources/undocommand/rotateselectioncommand.h

@@ -21,10 +21,12 @@
 #include <QUndoCommand>
 #include <QPointer>
 #include <QHash>
+#include <QPointF>
 
 class Diagram;
 class ConductorTextItem;
 class QPropertyUndoCommand;
+class QGraphicsItem;
 
 /**
 	@brief The RotateSelectionCommand class
@@ -33,13 +35,15 @@ class QPropertyUndoCommand;
 class RotateSelectionCommand : public QUndoCommand
 {
 	public:
-		RotateSelectionCommand(Diagram *diagram, qreal angle=90, QUndoCommand *parent=nullptr);
+		RotateSelectionCommand(Diagram *diagram, qreal angle=90, QUndoCommand *parent=nullptr, bool rotate_as_group=false);
 		void undo() override;
 		void redo() override;
 
 		bool isValid();
 
 	private:
+		void addGroupPositionUndo(QGraphicsItem *item, const QPointF &pivot, qreal angle);
+
 		Diagram *m_diagram =nullptr;
 
 		QList<QPointer<ConductorTextItem>> m_cond_text;