%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 \& \CONTEXT\ Development Team}]
%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}

%D Currently there is a limitation in mixed inline usage. This has to do with the fact
%D that we have a stacked model but cannot determine where to revert to (as we can
%D have AABBCCAA ranges). Maybe I'll solve that one day. It only affects nested inline
%D layers and these make not much sense anyway. We'd have to store the complete nesting
%D stack in the attribute in order to be able to cross pages and that demands a new
%D mechanism.

\unprotect

\registerctxluafile{attr-lay}{}

% needs to work over stopitemize grouping etc

\installcorenamespace{viewerlayer}

\installcommandhandler \??viewerlayer {viewerlayer} \??viewerlayer

\setupviewerlayer
  [\c!state=\v!start,
   \c!title=,
   \c!export=\v!yes, % exportable is ugly
   \c!printable=\v!yes,
   \c!scope=\v!local, % maybe global but needs checking with layout
   \c!method=\v!none]

\appendtoks
  \clf_defineviewerlayer
       tag       {\currentviewerlayer}%
       title     {\viewerlayerparameter\c!title}%
       visible   {\viewerlayerparameter\c!state}%
       editable  {\v!yes}%
       export    {\viewerlayerparameter\c!export}%
       printable {\viewerlayerparameter\c!printable}%
       scope     {\viewerlayerparameter\c!scope}%
  \relax
  \doif{\viewerlayerparameter\c!method}\v!command
    {\setuxvalue{\e!start#1}{\startviewerlayer[\currentviewerlayer]}%
     \setuxvalue{\e!stop #1}{\stopviewerlayer}}%
\to \everydefineviewerlayer

\unexpanded\def\startviewerlayer[#1]{\clf_startviewerlayer{#1}}% not grouped
\unexpanded\def\stopviewerlayer     {\clf_stopviewerlayer}     % not grouped
\unexpanded\def\viewerlayer     [#1]{\groupedcommand
                                    {\clf_startviewerlayer{#1}}% grouped
                                    {\clf_stopviewerlayer}}    % grouped

% some day we will keep this at the lua end as the info is only needed there

\newtoks\currentviewerlayertoks % soon we can set macros at the lua end

\def\currentviewerlayer{\the\currentviewerlayertoks}

\appendtoks
    \let\currentviewerlayer\empty
\to \everybeforepagebody

% layout components are implemented rather directly (speed)

\installcorenamespace{layoutcomponentattribute}

\def\attr_layoutcomponent_initialize#1%
  {\edef\layoutcomponentboxattribute{\clf_definedlayoutcomponent{#1}}%
   \edef\layoutcomponentboxattribute{attr \viewerlayerattribute \layoutcomponentboxattribute\relax}%
   \expandafter\glet\csname\??layoutcomponentattribute#1\endcsname\layoutcomponentboxattribute}

\def\attr_layoutcomponent_set#1% make this faster
  {\expandafter\let\expandafter\layoutcomponentboxattribute\csname\??layoutcomponentattribute#1\endcsname
   \ifx\layoutcomponentboxattribute\relax
     \attr_layoutcomponent_initialize{#1}% get rid of { }
   \fi}

\def\attr_layoutcomponent_reset
  {\let\layoutcomponentboxattribute\empty}

\let\setlayoutcomponentattribute  \gobbleoneargument
\let\resetlayoutcomponentattribute\relax
\let\layoutcomponentboxattribute  \empty

\unexpanded\def\showlayoutcomponents
  {\let\setlayoutcomponentattribute  \attr_layoutcomponent_set
   \let\resetlayoutcomponentattribute\attr_layoutcomponent_reset}

\unexpanded\def\attr_layoutcomponent_cleanup
  {\clf_cleanuplayers}

\appendtoks
    \attr_layoutcomponent_cleanup
\to \everyshipout

\protect \endinput