Difference between revisions of "TextBackground"

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< [[Main Page]] | [[Visuals]] >
 
 
 
{{todo|Add more examples of usage of textbackgrounds.}}
 
{{todo|Add more examples of usage of textbackgrounds.}}
  
Pages, paragraphs, words can have a background: color or screen.
+
Pages, paragraphs, words can have a background color or frame. ConTeXt creates these using [[MetaPost]].
 
 
(See, eventually, the [[manual:details.pdf| details]] manual for further explanations.)
 
 
 
== What if textbackground doesn't work? ==
 
  
The textbackground commands require [[write18]] to be enabled; see that page for more information.
+
(See, eventually, the [[manual:details.pdf| details]] manual or the {{src|anch-bck.mkvi|source}} for further explanations.)
  
 
== Example: multi-page backgrounded text ==
 
== Example: multi-page backgrounded text ==
Line 19: Line 13:
 
In the following example, we also reduce the textwidth and bodyfont size.
 
In the following example, we also reduce the textwidth and bodyfont size.
 
<context source="yes">
 
<context source="yes">
\setupcolors[state=start]
+
\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}
 +
</context>
 +
 +
== Background Offset ==
 +
 +
The options left, right, top, bottomoffset can be replaced by backgroundoffset yielding a different result:
 +
 +
<context source="yes">
 
\definetextbackground[secondary][
 
\definetextbackground[secondary][
        location=paragraph,
+
  location=paragraph,
        background=color,backgroundcolor=middlegray,
+
  background=color,
        leftoffset=.5\bodyfontsize,rightoffset=.5\bodyfontsize,
+
  backgroundcolor=lightgray,
        topoffset=.5\bodyfontsize,bottomoffset=.5\bodyfontsize,
+
  backgroundoffset=.5\bodyfontsize,
        before={\startnarrower\switchtobodyfont[small]},
+
  before={\startnarrower\switchtobodyfont[small]},
        after={\stopnarrower},
+
  after={\stopnarrower},
        frame=off]
+
  frame=off,]
  
\starttext
+
\samplefile{knuth}
 
 
\input knuth
 
  
 
\startsecondary
 
\startsecondary
\input knuth
+
\samplefile{knuth}
 
\stopsecondary
 
\stopsecondary
  
\input knuth
+
\samplefile{knuth}
 +
</context>
 +
 
 +
== Underlining with Text Backgrounds ==
 +
 
 +
Underlining is generally frowned upon by experienced TeXnicians. Occasionally,
 +
however, it is necessary and {{cmd|ul}} or {{cmd|underbar}} doesn’t do what you want. In those
 +
cases using {{cmd|definetextbackground}} for the underlining may also be tried.
  
\stoptext
+
<context source="yes">
</context>
+
\definetextbackground[underline]
 +
  [location=text,alternative=1,background=,frame=off]
  
{{todo|The background does not show here using the live, online conTeXt processor. Why?}}
+
\definestartstop[underline]
 +
  [before={\starttextbackground[underline]},
 +
  after=\stoptextbackground]
  
== backgroundoffset ==
+
\startTEXpage
 +
An example with \startunderline underlined\stopunderline\ text.
 +
\stopTEXpage
 +
</context>
  
The options left, right, top, bottomoffset can be replaced by backgroundoffset yielding a different result:
+
If desired, the location of the line can also be adjusted.
  
 
<context source="yes">
 
<context source="yes">
\setupcolors[state=start]
+
\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]
  
\definetextbackground[secondary][
+
\definestartstop[underline]
        location=paragraph,
+
  [before={\starttextbackground[underline]},
        background=color,backgroundcolor=middlegray,
+
  after=\stoptextbackground]
        backgroundoffset=.5\bodyfontsize,
 
        before={\startnarrower\switchtobodyfont[small]},
 
        after={\stopnarrower},
 
        frame=off]
 
  
\starttext
+
\startTEXpage
 +
An example with \startunderline underlined\stopunderline\ text.
 +
\stopTEXpage
 +
</context>
  
\input knuth
 
  
\startsecondary
+
=== Example: dashed underbar ===
\input knuth
+
(by WS, 4/2011)
\stopsecondary
 
  
\input knuth
+
<context source="yes">
 +
\definetextbackground
 +
  [dashed]
 +
  [location=text,
 +
  framecolor=black,
 +
  alternative=1,
 +
  voffset=-\strutdp,
 +
  background=,
 +
  frame=off,
 +
  dash=1]
  
\stoptext
+
\startdashed
 +
\samplefile{ward}
 +
\stopdashed
 
</context>
 
</context>
 +
 +
[[Category:Basics]]

Revision as of 15:06, 31 August 2021


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