ConTeXt: Place rules above and below floating figure

Question

I'm experimenting to place a rule above and below a floating figure to achieve the following design. But to no avail.

I've tried to place a \blackrule before and after the \placefigure. But that's obviously not gonna work since the float floats around the document without taking the rule with it.

EDIT:

I tried the following code, which doesn't quite do the trick. I need the rule above the caption.

\startplacefigure \blackrule[width=\textwidth,height=.8pt,color=red] \externalfigure[kitten.jpg][width=\textwidth] \blackrule[width=\textwidth,height=.8pt,color=red] \stopplacefigure

Answer 1

AFAIK, there is no in-built option for this, but it is relatively straight forward to implement using the core commands:

\def\floatbackrule{\blackrule[width=\textwidth,height=.8pt,color=red]}

\unprotect
\installfloatboxbuilder {topframed}    \strc_floats_build_box_top_framed
\installfloatboxbuilder {bottomframed} \strc_floats_build_box_bottom_framed

\def\strc_floats_build_box_top_framed
    {\floatbackrule
     \strc_floats_build_box_top
     \floatbackrule}

\def\strc_floats_build_box_bottom_framed
    {\floatbackrule
     \strc_floats_build_box_bottom
     \floatbackrule}

\protect

Here is an example:

\setupcaption
  [
    location=topframed,
  ]

\setupexternalfigures[location={local,global,default}] 

\starttext 

\section{A figure with rules} 

\input knuth

\startplacefigure[title={A dutch cow}, location=top]
  \externalfigure[cow]
\stopplacefigure

\dorecurse{4}{\input knuth \endgraf}

\stoptext

which gives:

Addendum: This simple method fails with longer captions and does not work with the align option. The reason is that an internal macro \strc_floats_prepare_page_caption does some corrections with the location parameter is top or bottom. These corrections don't take place when location is set to topframed. To fix this, we need to patch `\strc_floats_prepare_page_caption' as follows:

\def\strc_floats_prepare_page_caption
  {\edef\p_strc_floats_caption_width   {\floatcaptionparameter\c!width}%
   \edef\p_strc_floats_caption_minwidth{\floatcaptionparameter\c!minwidth}%
   \edef\p_strc_floats_caption_align   {\floatcaptionparameter\c!align}%
   \dostarttagged\t!floatcaption\empty
   \doifcommonelse\floatcaptionlocation{\v!top,\v!bottom,topframed,bottomframed}
      {\strc_floats_prepare_page_caption_top_bottom}
      {\ifx\p_strc_floats_caption_width\v!fit
         \strc_floats_prepare_side_auto_caption
       \else\ifx\p_strc_floats_caption_width\v!max
         \strc_floats_prepare_side_auto_caption
       \else
         \strc_floats_prepare_side_width_caption
      \fi\fi}%
   \dostoptagged}

Here is a complete example:

\setupexternalfigures[location={local,global,default}] 

\def\floatbackrule{\blackrule[width=\textwidth,height=.8pt,color=red]}

\unprotect
\installfloatboxbuilder {topframed}    \strc_floats_build_box_top_framed
\installfloatboxbuilder {bottomframed} \strc_floats_build_box_bottom_framed

\def\strc_floats_build_box_top_framed
    {\floatbackrule
     \strc_floats_build_box_top
     \floatbackrule}

\def\strc_floats_build_box_bottom_framed
    {\floatbackrule
     \strc_floats_build_box_bottom
     \floatbackrule}

\def\strc_floats_prepare_page_caption
  {\edef\p_strc_floats_caption_width   {\floatcaptionparameter\c!width}%
   \edef\p_strc_floats_caption_minwidth{\floatcaptionparameter\c!minwidth}%
   \edef\p_strc_floats_caption_align   {\floatcaptionparameter\c!align}%
   \dostarttagged\t!floatcaption\empty
   \doifcommonelse\floatcaptionlocation{\v!top,\v!bottom,topframed,bottomframed}
      {\strc_floats_prepare_page_caption_top_bottom}
      {\ifx\p_strc_floats_caption_width\v!fit
         \strc_floats_prepare_side_auto_caption
       \else\ifx\p_strc_floats_caption_width\v!max
         \strc_floats_prepare_side_auto_caption
       \else
         \strc_floats_prepare_side_width_caption
      \fi\fi}%
   \dostoptagged}

\protect


\setupcaption
  [
    location=topframed,
    align=flushleft,
    width=\textwidth,
  ]
\starttext 

\section{A figure with rules} 

\input knuth

\startplacefigure[title={\input zapf \relax}]
  \externalfigure[cow]
\stopplacefigure

\dorecurse{4}{\input knuth \endgraf}

\stoptext

which gives

Answer 2

The next ConTeXt version will have the new command \setupfloatframed which can be used to set a background for the whole float block. The command takes the same arguments as \setupframed and the syntax for it is shown in the following image.

In addition to setting a background for the whole float you can also set individual backgrounds for the caption or the content of a float. To set the values for both elements you have to use the \setupcaption and \setupfloat commands which accept also the arguments of \setupframed.

\setupexternalfigures[location={local,global,default}]

\setupcaption
  [figure]
  [location=top]

\setupfloatframed
  [figure]
  [width=max,
   toffset=1.5ex,
   boffset=1.5ex,
   framecolor=red,
   topframe=on,
   bottomframe=on]

\starttext

\samplefile{weisman}

\startplacefigure[title={A dutch cow}]
  \externalfigure[cow][width=6cm]
\stopplacefigure

\samplefile{weisman}

\setupfloat       [intermezzo] [background=color,backgroundcolor=red]
\setupcaption     [intermezzo] [background=color,backgroundcolor=blue]
\setupfloatframed [intermezzo] [background=color,backgroundcolor=green]

\startplaceintermezzo[title={Another cow}]
  \externalfigure[cow][width=6cm]
\stopplaceintermezzo

\samplefile{weisman}

\stoptext