[NTG-context] Float captions with hanging indentation

9 Oct 2009

      Hello,

I am a new ConTeXt user recently switched from LaTeX (with small amounts 
of raw TeX macrosity) which I used for several years.

I was searching the internet, this mailing list and finally the ConTeXt 
sources to find some information about achieving hanging indentation in 
captions. The 'hang' option for the 'caption' LaTeX package [1] was my 
inspiration (you can see an example on the 3 page of the linked manual). 
The only thing I could find was an old reply from Taco Hoekwater [2] but 
as he mentions this does not work well.

After digging inside the source code of both ConTeXt and caption.sty
I managed to hack the \putcompletecaption macro to do what I need. (see 
below)

The changes required are minimal (capture the caption head into a box, 
remember its width and later set \hangindent and \hangafter while 
typessing the caption body) so maybe this could go into the main ConTeXt 
tree? Unfortunately I do not know how to make use of the setup macros so 
this currently hardcodes the hanging indentation.

\unprotect
\newdimen\captionhang
\def\putcompletecaption#1#2%

{\doifsomething{\floatcaptionparameter\c!spacebefore}{\blank[\floatcaptionparameter\c!spacebefore]}%
% \floatcaptionparameter\c!before % test for side effects first
    \noindent
    \xdef\lastcaptiontag{\strut#1}%
    \dostartattributes{\??kj\currentfloat}\c!style\c!color\empty
      \setbox0\hbox{%
        \ifnofloatnumber
        \else

\hbox{\doattributes{\??kj\currentfloat}\c!headstyle\c!headcolor{\strut#1}}%
          \ifnofloatcaption \else \ifemptyfloatcaption \else
            \doifelsenothing{\floatcaptionparameter\c!spaceinbetween}
              {\scratchskip\floatcaptionparameter\c!distance\relax
               \dotfskip\scratchskip\emergencystretch.5\scratchskip}
              {\blank[\floatcaptionparameter\c!spaceinbetween]}%
          \fi \fi
        \fi
      }%
      \captionhang=\wd0\unhbox0%
      \ifnofloatcaption
        \globallet\lastcaptionht\!!zeropoint
        \globallet\lastcaptiondp\!!zeropoint
      \else
        \doattributes{\??kj\currentfloat}\c!textstyle\c!textcolor
          {\hangindent=\captionhang\hangafter=1%
           \xdef\lastcaptionht{\strutheight}%
           \xdef\lastcaptiondp{\strutdepth}%
           \begstrut#2\endstrut\endgraf}%
      \fi
    \dostopattributes
% \floatcaptionparameter\c!after % test for side effects first

\doifsomething{\floatcaptionparameter\c!spaceafter}{\blank[\floatcaptionparameter\c!spaceafter]}}
\protect

[1]: http://www.dd.chalmers.se/latex/Docs/PDF/caption.pdf
[2]: http://thread.gmane.org/gmane.comp.tex.context/21675/focus=21676

-- 
regards,
Jakub Piotr Cłapa