code: private final double getNodeParentsAlpha(Node<?> node)
      {
          double alpha = 1;
  
          node = node.getParent();
  
          while (null != node)
          {
              alpha = alpha * node.getAttributes().getAlpha();
  
              node = node.getParent();
  
              if ((null != node) && (node.getNodeType() == NodeType.LAYER))
              {
                  node = null;
              }
          }
          return alpha;
      }
docs: Returns global alpha value.
  
  @return double