%D \module
%D   [       file=attr-lay,
%D        version=2007.06.06,
%D          title=\CONTEXT\ Attribute Macros,
%D       subtitle=Viewerlayers,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright=PRAGMA-ADE]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Attribute Macros / Viewerlayers}

\unprotect

\registerctxluafile{attr-lay}{1.001}

% needs to work over stopitemize grouping etc

\def\registerviewerlayer#1#2% global !
  {\setxvalue{(vl:#1)}{\global\attribute\viewerlayerattribute\ctxlua{tex.write(attributes.viewerlayers.register('#2'))} }}

\setevalue{(vl:)}{\global\attribute\viewerlayerattribute\attributeunsetvalue}

\def\dotriggerviewerlayer % move to lua
  {\ctxlua{attributes.viewerlayers.enable()}%
   \gdef\dotriggerviewerlayer##1{\csname(vl:##1)\endcsname}%
   \dotriggerviewerlayer}

\protect \endinput