moveNodeDrag method

void moveNodeDrag(Offset graphDelta)

Moves nodes during a drag operation.

Call this from NodeWidget's GestureDetector.onPanUpdate. The delta is already in graph coordinates since GestureDetector is inside InteractiveViewer's transformed space - no conversion needed.

Parameters:

• graphDelta: The movement delta in graph coordinates

Implementation

void moveNodeDrag(Offset graphDelta) {
  final draggedNodeId = interaction.draggedNodeId.value;
  if (draggedNodeId == null) return;

  // Collect nodes that will be moved for event firing
  final movedNodes = <Node<T>>[];

  // Get nodes to move
  final nodeIdsToMove = selectedNodeIds.contains(draggedNodeId)
      ? selectedNodeIds.toList()
      : [draggedNodeId];

  final context = _createDragContext();

  runInAction(() {
    // Update node positions and visual positions
    for (final nodeId in nodeIdsToMove) {
      final node = _nodes[nodeId];
      if (node != null) {
        final newPosition = node.position.value + graphDelta;
        node.position.value = newPosition;
        // Update visual position with snapping
        node.setVisualPosition(_config.snapToGridIfEnabled(newPosition));
        movedNodes.add(node);

        // Notify the node of its own drag move
        node.onDragMove(graphDelta, context);
      }
    }
  });

  // Mark moved nodes dirty for spatial index
  internalMarkNodesDirty(movedNodes.map((n) => n.id));

  // Fire drag event for all moved nodes
  for (final node in movedNodes) {
    events.node?.onDrag?.call(node);
  }
}