%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

\def\c!printable{printable} % todo

\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}

\getparameters
  [\??lr]
  [\c!state=\v!start,
   \c!title=,
   \c!printable=\v!yes,
   \c!method=\v!none]

\def\defineviewerlayer
  {\dodoubleargument\dodefineviewerlayer}

\def\dodefineviewerlayer[#1][#2]% document wide properties
  {\begingroup
   \getparameters[\??lr][#2]%
   \ctxlua{attributes.viewerlayers.define{
        tag       = "#1",
        title     = "\@@lrtitle",
        visible   = "\@@lrstate",
        kind      = 0, % 1 == frozen
        printable = "\@@lrprintable",
   }}%
   \doif\@@lrmethod\v!command
     {\setugvalue{\e!start#1}{\startviewerlayer[#1]}%
      \setugvalue{\e!stop #1}{\stopviewerlayer     }}%
   \endgroup}

\unexpanded\def\startviewerlayer[#1]{\ctxlua{attributes.viewerlayers.start("#1")}}             % not grouped
\unexpanded\def\stopviewerlayer     {\ctxlua{attributes.viewerlayers.stop()}}                  % not grouped
\unexpanded\def\viewerlayer     [#1]{\groupedcommand{\startviewerlayer[#1]}{\stopviewerlayer}} % grouped

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

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

\def\currentviewerlayer{\the\currentviewerlayertoks}

\appendtoks
    \let\currentviewerlayer\empty
\to \everypagebody

% layout components are implemented rather directly (speed)

\def\doinitializelayoutcomponent#1#2%
  {\ctxlua{backends.codeinjections.defineviewerlayer{% this will move to the lua end i.e be merged with register
     tag       = "#1:#2",
     title     = "#1 #2",
     visible   = "\v!start",
     kind      = 0, % 1 == frozen
     printable = "\v!yes"
   }}%
   \edef\layoutcomponentboxattribute{attr \viewerlayerattribute \ctxlua{tex.write(attributes.viewerlayers.register('#1:#2',true))}\relax}%
   \expandafter\glet\csname\??ly>#1:#2\endcsname\layoutcomponentboxattribute}

\def\dosetlayoutcomponentattribute#1#2% make this faster
  {\expandafter\let\expandafter\layoutcomponentboxattribute\csname\??ly>#1:#2\endcsname
   \ifx\layoutcomponentboxattribute\relax
     \doinitializelayoutcomponent{#1}{#2}% get rid of { }
   \fi}

\def\doresetlayoutcomponentattribute
  {\let\layoutcomponentboxattribute\empty}

\let\setlayoutcomponentattribute  \gobbletwoarguments
\let\resetlayoutcomponentattribute\relax
\let\layoutcomponentboxattribute  \empty

\def\showlayoutcomponents
  {\ctxlua{attributes.viewerlayers.enable()}%
   \let\setlayoutcomponentattribute  \dosetlayoutcomponentattribute
   \let\resetlayoutcomponentattribute\doresetlayoutcomponentattribute}


\protect \endinput