Restore the old reference after rotation or flip instead of clearing

After a rotation or flip the reference point has to be restored to the
previous value to prevent the dragged item from warping to the cursor.
Before this change, the reference point was only cleared, causing odd
behavior when a rotation or flip was performed.

Fixes https://gitlab.com/kicad/code/kicad/issues/7112

pcbnew/tools/edit_tool.cpp

@@ -1293,8 +1293,16 @@ int EDIT_TOOL::Rotate( const TOOL_EVENT& aEvent )
     if( selection.Empty() )
         return 0;
 
+    OPT<VECTOR2I> oldRefPt;
+
+    if( selection.HasReferencePoint() )
+        oldRefPt = selection.GetReferencePoint();
+    else
+        oldRefPt = NULLOPT;
+
     updateModificationPoint( selection );
-    auto refPt = selection.GetReferencePoint();
+
+    VECTOR2I refPt = selection.GetReferencePoint();
     const int rotateAngle = TOOL_EVT_UTILS::GetEventRotationAngle( *editFrame, aEvent );
 
     // When editing footprints, all items have the same parent
@@ -1332,9 +1340,12 @@ int EDIT_TOOL::Rotate( const TOOL_EVENT& aEvent )
     if( m_dragging )
         m_toolMgr->RunAction( PCB_ACTIONS::updateLocalRatsnest, false );
 
-    // Clear reference so any mouse dragging that occurs doesn't make the selection jump
+    // Restore the old reference so any mouse dragging that occurs doesn't make the selection jump
     // to this now invalid reference
-    selection.ClearReferencePoint();
+    if( oldRefPt != NULLOPT )
+        selection.SetReferencePoint( *oldRefPt );
+    else
+        selection.ClearReferencePoint();
 
     return 0;
 }
@@ -1538,19 +1549,26 @@ int EDIT_TOOL::Flip( const TOOL_EVENT& aEvent )
     if( selection.Empty() )
         return 0;
 
+    OPT<VECTOR2I> oldRefPt;
+
+    if( selection.HasReferencePoint() )
+        oldRefPt = selection.GetReferencePoint();
+    else
+        oldRefPt = NULLOPT;
+
     updateModificationPoint( selection );
 
     // Flip around the anchor for footprints, and the bounding box center for board items
-    VECTOR2I modPoint = IsFootprintEditor() ? VECTOR2I( 0, 0 ) : selection.GetCenter();
+    VECTOR2I refPt = IsFootprintEditor() ? VECTOR2I( 0, 0 ) : selection.GetCenter();
 
     // If only one item selected, flip around the selection or item anchor point (instead
     // of the bounding box center) to avoid moving the item anchor
     if( selection.GetSize() == 1 )
     {
         if( m_dragging && selection.HasReferencePoint() )
-            modPoint = selection.GetReferencePoint();
+            refPt = selection.GetReferencePoint();
         else
-            modPoint = static_cast<BOARD_ITEM*>( selection.GetItem( 0 ) )->GetPosition();
+            refPt = static_cast<BOARD_ITEM*>( selection.GetItem( 0 ) )->GetPosition();
     }
 
     bool leftRight = frame()->Settings().m_FlipLeftRight;
@@ -1572,7 +1590,7 @@ int EDIT_TOOL::Flip( const TOOL_EVENT& aEvent )
                                                                });
         }
 
-        static_cast<BOARD_ITEM*>( item )->Flip( modPoint, leftRight );
+        static_cast<BOARD_ITEM*>( item )->Flip( refPt, leftRight );
     }
 
     if( !m_dragging )
@@ -1586,9 +1604,12 @@ int EDIT_TOOL::Flip( const TOOL_EVENT& aEvent )
     if( m_dragging )
         m_toolMgr->RunAction( PCB_ACTIONS::updateLocalRatsnest, false );
 
-    // Clear reference so any mouse dragging that occurs doesn't make the selection jump
+    // Restore the old reference so any mouse dragging that occurs doesn't make the selection jump
     // to this now invalid reference
-    selection.ClearReferencePoint();
+    if( oldRefPt != NULLOPT )
+        selection.SetReferencePoint( *oldRefPt );
+    else
+        selection.ClearReferencePoint();
 
     return 0;
 }