Command/setupsidebar

• \definesidebar[simple][rulethickness=1pt,distance=4pt]
  \starttext
  \hsize=4cm
  The sidebar follows the text between \type{\startsidebar[simple]} and \type{\stopsidebar},
  \startsidebar[simple] {\blue from the top of the first line to the bottom of the last line.}\stopsidebar
  Here the text between \type{\startsidebar[simple]} and \type{\stopsidebar} has been colored in blue.
  
  \blank
  
  When the \startsidebar[simple] same bar is started twice on the same text, \startsidebar[simple]
  a second bar \stopsidebar will be drawn, with an offset equal to the \type{distance} parameter.\stopsidebar
  
  \blank
  
  \setupsidebar[simple][leftmargindistance=0pt,distance=4pt]
  When \type{leftmargindistance} is zero, \startsidebar[simple]
  the bar is drawn at distance \type{distance} from the left edge
  of the text,\stopsidebar which means 4pt in this example.
  
  \blank
  
  \setupsidebar[simple][leftmargindistance=0.1pt,distance=4pt]
  When \type{leftmargindistance} is not zero, \startsidebar[simple]
  the bar is drawn at distance \type{leftmargindistance} from the left edge
  of the text, which means 0.1pt in this example.
  \startsidebar[simple] A second bar will be drawn at distance \type{distance}
  from the first one.\stopsidebar\stopsidebar
  
  \blank
  
  \setupsidebar[simple][leftmargindistance=0pt,distance=4mm,rulethickness=2mm,level=1]
  \definesidebar[over][distance=4mm,rulethickness=1mm,rulecolor=green,level=1]
  When \startsidebar[simple]\startsidebar[over] two sidebars are in the same level,
  they are drawn at distance \type{distance}.\stopsidebar\stopsidebar
  
  \blank
  
  \setupsidebar[over][level=2]
  When \startsidebar[simple]\startsidebar[over] two sidebars are in different levels,
  they are drawn as if they were in different layers.\stopsidebar\stopsidebar
  
  \blank
  
  \setupsidebar[simple][rulethickness=1pt,leftmargindistance=\dimexpr -\hsize - 4pt\relax]
  \startsidebar[simple] You can put a bar in the right margin.\stopsidebar
  
  \stoptext
  

• 

You can define fancy, zig zag bars redefining the anch_sidebars_draw macro:

• \definesidebar[zigzag1][rulecolor=black,distance=4pt,rulethickness=1pt,alternative=2]
  \definesidebar[zigzag2][rulecolor=red,distance=4pt,rulethickness=1pt,alternative=3]
  \definesidebar[wave1][rulecolor=blue,distance=4pt,rulethickness=1pt,alternative=4]
  \definesidebar[wave2][rulecolor=cyan,distance=4pt,rulethickness=1pt,alternative=5]
  \definesidebar[obliquedashes][rulecolor=darkgreen,distance=4pt,rulethickness=1pt,alternative=6]
  
  \startMPcode
  % draws a bar repeating a pattern defined from (0,0) to (0,1)
  def draw_pattern_bar(expr a, b, pattern, patternlength, patternheight, linewidth, linecolor) =
     draw image (
         begingroup ;
             save p, q, stp ;
             pair p, q, stp ;
             stp := ( ( b - a ) / arclength( a -- b ) ) * patternlength ;
             path q ; q := pattern xscaled patternlength yscaled patternheight rotated (angle(stp)) ;
             p := a ;
             forever :
                 draw
                     q shifted p
                     withpen pencircle scaled linewidth
                     withcolor linecolor ;
                 p := p + stp ;
                 exitif arclength( a -- p ) > arclength( a -- b ) ;
             endfor ;
         endgroup ;
         clip currentpicture to
             (xpart llcorner currentpicture, ypart b) --
             (xpart lrcorner currentpicture, ypart b) --
             (xpart urcorner currentpicture, ypart a) --
             (xpart ulcorner currentpicture, ypart a) -- cycle ;
     ) ;
  enddef ;
  
  % modified from metapost/context/base/mpiv/mp-apos.mpiv to add alternatives
  def anch_sidebars_draw (expr p_b_self, p_e_self, y_b_self, y_e_self, h_b_self, d_e_self,
          x, y, w, h, alternative, distance, linewidth, linecolor, topoffset, bottomoffset) =
      % beware, we anchor at (x,y)
      begingroup ;
      if alternative = 1 :
          interim linecap := rounded ;
      else :
          interim linecap := butt ;
      fi ;
      save a, b ; pair a, b ;
      if p_b_self = p_e_self :
          a := (-distance,y_b_self+h_b_self-y) ;
          b := (-distance,y_e_self-d_e_self-y) ;
      elseif RealPageNumber = p_b_self :
          a := (-distance,y_b_self+h_b_self-y) ;
          b := (-distance,0) ;
      elseif RealPageNumber = p_e_self :
          a := (-distance,h) ;
          b := (-distance,y_e_self-d_e_self-y) ;
      else :
          a := (-distance,h) ;
          b := (-distance,0) ;
      fi ;
      a := (xpart a, min(ypart a + topoffset,   h)) ;
      b := (xpart b, max(ypart b - bottomoffset,0)) ;
      if alternative = 2 :
          draw_pattern_bar( a, b, ((0,0)--(0.25,-0.5)--(0.75,0.5)--(1,0)), 2pt, 2pt, linewidth, linecolor ) ;
      elseif alternative = 3 :
          draw_pattern_bar( a, b, ((0,0)--(0.25,-0.5)--(0.75,0.5)--(1,0)), 4pt, 1.5pt, linewidth, linecolor ) ;
      elseif alternative = 4 :
          draw_pattern_bar( a, b, ( ((0,0) .. controls (0,0.5) and (0.5,0.5) .. (0.5,0)) -- ((0.5,0) .. controls (0.5,-0.5) and (1,-0.5) .. (1,0)) ), 6pt, 4pt, linewidth, linecolor ) ;
      elseif alternative = 5 :
          draw_pattern_bar( a, b, ( (0,0) .. controls (0,1) and (1,1) .. (1,0) ), 4pt, 2pt, linewidth, linecolor ) ;
      elseif alternative = 6 :
          draw_pattern_bar( a, b, ( (0,0.5) .. (1,-0.5) ), 4pt, 2pt, linewidth, linecolor ) ;
      else :
          draw
              a -- b
              if alternative = 1 :
                  dashed (withdots scaled (linewidth/2))
              fi
              withpen pencircle scaled linewidth
              withcolor linecolor ;
      fi ;
      endgroup ;
  enddef ;
  \stopMPcode
  
  \def\samplewithbar#1{The sidebar follows the text
    between \type{\startsidebar[...]} and \type{\stopsidebar},
    \startsidebar[#1] {\blue from the top of the first line to the bottom of the last line.}\stopsidebar
    Here the text between \type{\startsidebar[...]} and \type{\stopsidebar} has been colored in blue.\par
    \blank}
  \starttext
  \hsize=4cm
  \samplewithbar{zigzag1}
  \samplewithbar{zigzag2}
  \samplewithbar{wave1}
  \samplewithbar{wave2}
  \samplewithbar{obliquedashes}
  \stoptext
  

• 

The metapost macro draw_pattern_bar draws a repeating pattern along the bar length. The pattern is a sort of waveform defined with a path from (0,0) to (1,0). Its bounding box should have a height of 1, so that the base waveform has amplitude 1.

The length of the pattern and its "amplitude" are magnified according to patternlength and patternheight.

The default \setupsidebar[location=left] and \setupsidebar[location=right]:

In doublesided typesetting with \setuppagenumbering[alternative=doublesided], \setupsidebar[location=inner] puts the sidebars always in the inner margin, while \setupsidebar[location=outer] puts them in the outer margin: