TextBackground

TODO: Add more examples of usage of textbackgrounds. (See: To-Do List)

Pages, paragraphs, words can have a background color or frame. ConTeXt creates these using MetaPost.

(See, eventually, the details manual or the source for further explanations.)

Example: multi-page backgrounded text

Perhaps one might like to offset examples from the running text, or signal to the reader that the following paragraphs contain secondary, detailed information that is of interest only to the specialists. This can be achieved using textbackground.

In contrast, Framed creates text blocks that do not span columns or pages.

In the following example, we also reduce the textwidth and bodyfont size.

\definetextbackground[secondary][
  location=paragraph,
  background=color,
  backgroundcolor=lightgray,
  leftoffset=.5\bodyfontsize,
  rightoffset=.5\bodyfontsize,
  topoffset=.5\bodyfontsize,
  bottomoffset=.5\bodyfontsize,
  before={\startnarrower\switchtobodyfont[small]},
  after={\stopnarrower},
  frame=off,]

\samplefile{knuth}

\startsecondary
\samplefile{knuth}
\stopsecondary

\samplefile{knuth}

Background Offset

The options left, right, top, bottomoffset can be replaced by backgroundoffset yielding a different result:

\definetextbackground[secondary][
  location=paragraph,
  background=color,
  backgroundcolor=lightgray,
  backgroundoffset=.5\bodyfontsize,
  before={\startnarrower\switchtobodyfont[small]},
  after={\stopnarrower},
  frame=off,]

\samplefile{knuth}

\startsecondary
\samplefile{knuth}
\stopsecondary

\samplefile{knuth}

Underlining with Text Backgrounds

Underlining is generally frowned upon by experienced TeXnicians. Occasionally, however, it is necessary and \ul or \underbar doesn’t do what you want. In those cases using \definetextbackground for the underlining may also be tried.

\definetextbackground[underline]
  [location=text,alternative=1,background=,frame=off]

\definestartstop[underline]
  [before={\starttextbackground[underline]},
   after=\stoptextbackground]

\startTEXpage
An example with \startunderline underlined\stopunderline\ text.
\stopTEXpage

If desired, the location of the line can also be adjusted.

\startuseMPgraphic{mpos:par:columnset} % Shift underlining down a touch
   \iftracepositions show_multi_pars \else draw_multi_pars \fi ;
   path p ; p := boundingbox currentpicture ;
   currentpicture := currentpicture shifted (0,-StrutDepth/3) ;
   setbounds currentpicture to p ;
\stopuseMPgraphic

\definetextbackground[underline]
  [location=text,alternative=1,background=,frame=off]

\definestartstop[underline]
  [before={\starttextbackground[underline]},
   after=\stoptextbackground]

\startTEXpage
An example with \startunderline underlined\stopunderline\ text.
\stopTEXpage

Example: dashed underbar

(by WS, 4/2011)

\definetextbackground
  [dashed]
  [location=text,
   framecolor=black,
   alternative=1,
   voffset=-\strutdp,
   background=,
   frame=off,
   dash=1]

\startdashed
\samplefile{ward}
\stopdashed