%D \module
%D   [       file=scrn-but, % moved code
%D        version=1995.01.01,
%D          title=\CONTEXT\ Core Macros,
%D       subtitle=Interaction,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
%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 Screen Macros / Buttons}

\unprotect

%D Buttons are just what their names says: things that can be
%D clicked (pushed) on. They are similar to \type{\goto},
%D except that the text argument is not interpreted.
%D Furthermore one can apply anything to them that can be done
%D with \type{\framed}.
%D
%D \startbuffer
%D \button[width=3cm,height=1.5cm]{Exit}[ExitViewer]
%D \stopbuffer
%D
%D \typebuffer
%D
%D gives
%D
%D \getbuffer
%D
%D This command is formally specified as:
%D
%D \showsetup{button}
%D
%D The characteristics can be set with:
%D
%D \showsetup{setupbuttons}

\unexpanded\def\setupbuttons
  {\dodoubleargument\getparameters[\??bt]}

\definecomplexorsimpleempty\button

\def\complexbutton
  {\docomplexbutton\??bt}

\presetlocalframed[\??bt]

\def\buttonparameter#1{\csname\??bt#1\endcsname} % simple version

\long\def\docomplexbutton#1[#2]#3#4% get rid of possible space before [#4]
  {\dodocomplexbutton#1[#2]{#3}#4} % #4 == [

\def\buttonframed{\dodoubleempty\localframed[\??bt]} % goodie

% #3=none is obsolete, just use empty=yes

\long\def\dodocomplexbutton#1[#2]#3[#4]% #3 can contain [] -> {#3} later
  {\begingroup
   \let\menuparameter\buttonparameter
   \doif{\buttonparameter\c!state}\v!stop\locationfalse
   \iflocation
     \setlocationboxyes#1[#2]{#3}[#4]%
   \fi
   \endgroup}

%D \macros
%D   {overlaybutton}
%D
%D For converience we provide:
%D
%D \starttyping
%D \overlaybutton[reference]
%D \stoptyping
%D
%D This command can be used to define overlays an/or can be
%D used in the whatevertext areas, like:
%D
%D \starttyping
%D \defineoverlay[PrevPage][\overlaybutton{PrevPage}]
%D \setupbackgrounds[page][background=PrevPage]
%D \setuptexttexts[\overlaybutton{NextPage}]
%D \stoptyping
%D
%D For practical reasons, this macro accepts square brackets
%D as well as braces.

\definecomplexorsimple\overlaybutton

\def\simpleoverlaybutton#1%
  {\complexoverlaybutton[#1]}

\def\complexoverlaybutton[#1]%
  {\iflocation
     \gotobox{\overlayfakebox}[#1]%
   \fi}

\def\overlayfakebox
  {\hbox
     {\setbox\scratchbox\null
      \wd\scratchbox\overlaywidth
      \ht\scratchbox\overlayheight
      \box\scratchbox}}

%D Done.

\setupbuttons
  [\c!state=\v!start,
   \c!width=\v!fit,
   \c!height=\v!broad,
   \c!offset=0.25em,
   \c!frame=\v!on,
   \c!background=,
   \c!backgroundcolor=,
   \c!foregroundstyle=\buttonparameter\c!style,
   \c!foregroundcolor=\buttonparameter\c!color,
   \c!style=\@@iastyle,
   \c!color=\@@iacolor,
   \c!contrastcolor=\@@iacontrastcolor,
   \c!samepage=\v!yes,
   \c!unknownreference=\v!yes,
   \c!distance=\zeropoint] % for menubuttons

\protect \endinput