%D \module
%D   [       file=meta-dum,
%D        version=2003.03.21,
%D          title=\METAPOST\ Graphics,
%D       subtitle=Dummy (External) Graphics,
%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.

\unprotect

%D This library overloads the normal external figure placeholder by a nicer one.
%D
%D \startbuffer
%D \useMPlibrary[dum]
%D
%D \startlinecorrection
%D \externalfigure[unknown-a][width=3cm,height=1cm]
%D \stoplinecorrection
%D
%D \startlinecorrection
%D \externalfigure[unknown-b][width=4cm,height=5cm]
%D \stoplinecorrection
%D \stopbuffer
%D
%D \typebuffer \getbuffer

\startmkivmode

%D Currently preparempvariables is unable to resolve number fractions like
%D reduction.

    \startuseMPgraphic{minifun::figure:placeholder}{width,height,reduction,color}
        begingroup ;
        save w, h, d, r, p, c, b ;
        numeric w, h, d, r ; path p ;
        if cmykcolor \MPvar{color} :
            cmykcolor c, b ; b := (0,0,0,0)
        else :
            color c, b ; b := (1,1,1)
        fi ;
        c := \MPvar{color} ;
        w := \MPvar{width} ;
        h := \MPvar{height} ;
        r := \MPvar{reduction} ;
        d := max(w,h) ;
        p := unitsquare xyscaled (w,h) ;
        fill p withcolor r[.5c,b] ;
        for i := 1 upto 60 :
            fill fullcircle
                scaled (d/5 randomized (d/5))
                shifted (center p randomized (d))
                withcolor r[c randomized(.3,.9),b] ;
        endfor ;
        clip currentpicture to p ;
        endgroup ;
    \stopuseMPgraphic

    \defineoverlay
      [figure:placeholder:graphic]
      [\useMPgraphic
         {minifun::figure:placeholder}%
         {width=\figurewidth,%
          height=\figureheight,%
          reduction=\externalfigureparameter\c!reduction,%
          color=placeholder:\the\c_grph_replacement_n}] % weird, why do we need to prefix the palette

\stopmkivmode

\startlmtxmode

    \defineMPparameterset
      [placeholder]
      [width=dimension,
       height=dimension,
       reduction=number,
       color=string,
       alternative=string]

    \defineoverlay
       [figure:placeholder:graphic]
       [{\useMPmacro
          [minifun]%
          [placeholder]%
          [width=\figurewidth,%
           height=\figureheight,%
           alternative=\externalfigureparameter\c!alternative,
           reduction=\externalfigureparameter\c!reduction,%
           color=placeholder:\the\c_grph_replacement_n]}]

\stoplmtxmode

\definepalet
  [placeholder]
  [1=red,2=green,3=blue,4=cyan,5=magenta,6=yellow]

\newinteger\c_grph_replacement_n

\setupexternalfigures
  [\c!reduction=0,
   \c!text=\v!yes]

\let\grph_include_replacement_saved\grph_include_replacement

\unexpanded\def\grph_include_replacement#1#2#3%
  {\begingroup
%    \setuppalet[placeholder]%
   \getpaletsize[placeholder]%
   \ifnum\c_grph_replacement_n=\zerocount
     \getrandomnumber\m_grph_replacement_n\plusone\paletsize
     \global\c_grph_replacement_n\m_grph_replacement_n\relax
   \else
     \global\advance\c_grph_replacement_n\plusone
   \fi
   \ifnum\c_grph_replacement_n>\paletsize
     \global\c_grph_replacement_n\plusone
   \fi
   \setupcurrentexternalfigure
     [\c!width=\figurewidth,
      \c!height=\figureheight,
      \c!frame=\v!off,
      \c!strut=\v!no,
      \c!align={\v!middle,\v!lohi},
      \c!background=figure:placeholder:graphic,
      \c!foregroundcolor=\s!white]%
   \doifelse{\externalfigureparameter\c!text}\v!yes
     {\edef\m_graphics_text_a{#1}\edef\m_graphics_text_a{\ifx\m_graphics_text_a\s!dummy\else\detokenize\expandafter{\m_graphics_text_a}\fi}%
      \edef\m_graphics_text_b{#2}\edef\m_graphics_text_b{\ifx\m_graphics_text_b\s!dummy\else\detokenize\expandafter{\m_graphics_text_b}\fi}%
      \edef\m_graphics_text_c{#3}\edef\m_graphics_text_c{\ifx\m_graphics_text_c\s!dummy\else\detokenize\expandafter{\m_graphics_text_c}\fi}%
      \infofont\setupinterlinespace\dohyphens
      \inheritedexternalfigureframed{\directsetup{figure:placeholder:text}}}%
     {\inheritedexternalfigureframed{}}%
   \endgroup}

\unexpanded\def\dummyfigure
  {\externalfigure[placeholder]}

\startsetups figure:placeholder:text
    \ifx\m_graphics_text_a\empty\else
        \strut name: \m_graphics_text_a\par
    \fi
    \ifx\m_graphics_text_b\empty\else
        \strut
        \ifx\m_graphics_text_a\empty
            \ifx\m_graphics_text_c\empty
            \else
                file:\space
            \fi
        \else
            file:\space
        \fi
        \m_graphics_text_b\par
    \fi
    \ifx\m_graphics_text_c\empty\else
        \strut state: \m_graphics_text_c\par
    \fi
\stopsetups

%D \starttyping
%D \externalfigure[mediashow.swf][comment={Alas, we have no nice preview},background=figure:comment]
%D \externalfigure[mediashow.swf][comment={Alas, we have no nice preview},background=figure:dummy]
%D \externalfigure[mediashow.swf][background=figure:dummy]
%D \stoptyping

\defineframed
  [figurecomment]
  [\c!background=\v!color,
   \c!backgroundcolor=\s!gray,
   \c!frame=\v!off,
   \c!foregroundstyle=\ttbf,
   \c!align={\v!middle,\v!lohi},
   \c!height=\figureheight,
   \c!width=\figurewidth]

\defineframed
  [figuredummy]
  [\c!background=figure:dummy:only,
   \c!foregroundcolor=\s!white,
   \c!backgroundcolor=\v!gray,
   \c!frame=\v!off,
   \c!foregroundstyle=\ttbf,
   \c!align={\v!middle,\v!lohi},
   \c!height=\figureheight,
   \c!width=\figurewidth]

\defineoverlay
  [figure:dummy:only]
  [\grph_include_replacement\empty\empty\empty]

\defineoverlay
  [figure:comment]
  [\figurecomment{\externalfigureparameter\c!comment}]

\defineoverlay
  [figure:dummy]
  [\figuredummy{\externalfigureparameter\c!comment}]

\setupexternalfigures
  [\c!comment=]

\protect

\continueifinputfile{meta-imp-dum.mkiv}

\starttext

    \externalfigure[whatever-missing]

    \blank

    \externalfigure[whatever-missing][width=2cm]

\stoptext

