%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
%D 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

% currently preparempvariables is unable to resolve number
% fractions like reduction

% June 22, 2003, this definition was patched to adapt itself
% to transparent colors, but ... in 2011 we no longer have
% is_transparent so we revert.
%
% \startuseMPgraphic{placeholder}{width,height,reduction,color}
%     numeric w, h, d, r ; color c, b, cc ; path p ; boolean t ;
%     t := is_transparent(\MPvar{color}) ;
%     c := not_transparent(\MPvar{color}) ;
%     b := not_transparent(white) ;
%     w := \MPvar{width} ;
%     h := \MPvar{height} ;
%     r := \MPvar{reduction} ;
%     d := max(w,h) ;
%     p := unitsquare xyscaled (w,h) ;
%     cc := r[.5c,b] ;
%     fill p withcolor if t : transparent(1,.5,cc) else : cc fi ;
%     for i := 1 upto 60 :
%         cc := r[c randomized(.3,.9),b] ;
%         fill fullcircle
%             scaled (d/5 randomized (d/5))
%             shifted (center p randomized (d))
%             withcolor if t : transparent(1,.5,cc) else : cc fi ;
%     endfor ;
%     clip currentpicture to p ;
% \stopuseMPgraphic

\startuseMPgraphic{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
     {figure:placeholder}%
     {width=\figurewidth,%
      height=\figureheight,%
      reduction=\externalfigureparameter\c!reduction,%
      color=placeholder:\the\c_grph_replacement_n}]

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

\newcount\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
   \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
