Undo restores whether a picture's pivot was placed by hand

A picture remembers whether its pivot was placed by hand: a hand-placed
pivot is saved and kept through a resize, a default one is not saved
and recentres after a resize. Two actions changed that flag outside
their undo step:

- applyCrop() marked the pivot as default after moving it to the centre
  of the kept region. After Ctrl+Z the pivot was back where the user
  had put it, but marked as default, so the next save dropped it.
- dragging the pivot handle marked it as hand-placed. After Ctrl+Z the
  pivot was back at the centre but still marked as hand-placed, so a
  later resize left it at the handle's anchor corner.

pivotIsCustom becomes a property, and both actions put it into their
undo command next to rawPivot. tst_imagecropundo checks that a project
saved after undoing a crop keeps its hand-placed pivot.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

sources/qetgraphicsitem/diagramimageitem.cpp

@@ -805,6 +805,7 @@ void DiagramImageItem::handlerMousePressEvent(int index, Qt::KeyboardModifiers m
 	m_vector_index = index;
 	m_original_pos = pos();
 	m_original_transform = m_transform;
+	m_original_pivotIsCustom = m_pivotIsCustom;
 
 	if (m_handleRoles.at(index) == HandleRole::Resize)
 	{
@@ -921,7 +922,12 @@ void DiagramImageItem::handlerMouseReleaseEvent(int index)
 					undo = new QUndoCommand(tr("Déplacer le centre de rotation d'une image"));
 					new QPropertyUndoCommand(this, "pos", m_original_pos, pos(), undo);
 					new QPropertyUndoCommand(this, "rawPivot", m_original_transform.pivot, m_transform.pivot, undo);
+					// dragPivot() marked the pivot as hand-placed; undoing
+					// the move has to take that back as well.
+					new QPropertyUndoCommand(this, "pivotIsCustom", m_original_pivotIsCustom, m_pivotIsCustom, undo);
 				}
+				else
+					m_pivotIsCustom = m_original_pivotIsCustom;   // dragged back to where it was: nothing to undo
 				break;
 		}
 
@@ -1991,7 +1997,7 @@ void DiagramImageItem::crop()
 	simply the whole base.
 
 	One undo step, which restores the pixmap, the position, the pivot
-	and the crop rectangle together.
+	(and whether it was hand-placed) and the crop rectangle together.
 	@return false if nothing was cropped: read-only folio, or a
 	rectangle that is empty, outside the original, or the current one.
 */
@@ -2032,7 +2038,10 @@ bool DiagramImageItem::applyCrop(const QRect &cropRect)
 							 QVariant::fromValue(newSource), undo);
 	new QPropertyUndoCommand(this, "pos", oldPos, newPos, undo);
 	new QPropertyUndoCommand(this, "rawPivot", oldPivot, newOriginPoint, undo);
-	m_pivotIsCustom = false;
+	// The pivot goes to the centre of the kept region, so it is no longer
+	// hand-placed -- until the crop is undone, which brings the old pivot
+	// back and must bring its flag back with it.
+	new QPropertyUndoCommand(this, "pivotIsCustom", m_pivotIsCustom, false, undo);
 	diagram()->undoStack().push(undo);
 	return true;
 }

sources/qetgraphicsitem/diagramimageitem.h

@@ -65,6 +65,10 @@ class DiagramImageItem : public QetGraphicsItem {
 	// would silently overwrite that already-correct pos() a second
 	// time. rawPivot exists solely for that one caller.
 	Q_PROPERTY(QPointF rawPivot READ pivot WRITE setPivotRaw NOTIFY transformChanged)
+	// Whether the pivot was placed by hand: a hand-placed pivot is saved
+	// and kept through a resize. Changes in the same undo step as the
+	// pivot itself, so that Ctrl+Z restores both.
+	Q_PROPERTY(bool pivotIsCustom READ pivotIsCustom WRITE setPivotIsCustom)
 
 	// constructors, destructor
 	public:
@@ -120,6 +124,8 @@ class DiagramImageItem : public QetGraphicsItem {
 	void editProperty() override;
 	void setPixmap(const QPixmap &pixmap);
 	QPixmap pixmap() const { return pixmap_; }
+	bool pivotIsCustom() const { return m_pivotIsCustom; }
+	void setPivotIsCustom(bool custom) { m_pivotIsCustom = custom; }
 	QRectF boundingRect() const override;
 	QString name() const override;
 
@@ -259,6 +265,7 @@ class DiagramImageItem : public QetGraphicsItem {
 	int m_vector_index = -1;
 	QPointF m_original_pos;   // scene position at the start of a resize/rotate/pivot drag, for Escape-to-cancel
 	ShapeTransform m_original_transform;
+	bool m_original_pivotIsCustom = false;
 	bool m_deferHandleReposition = false;   // see setPivot()'s comment
 	// Optional caption drawn centred under the picture (issue #349).
 	// Empty by default, and then neither saved nor painted, so a picture