Graphics and media/Collections of tips and tricks/Repetition of a text element to fill a bar using textext

Imagine you want to create a frame which consists out of one glyph or a combination of different glyphs in order to make a decorative border. For this purpose a series of such elements should be placed on the bar as pictures, evenly spaced. Probably you want to have at the end of the bar a different glyph inserted as a picture too.

The following code is working but the last picture is not the expected glyph. One would expect 14 times the "?" and at the end of the bar a "*":

• \starttext
     \startMPpage
        picture PicA ; PicA := textext("*");
        picture PicB ; PicB := textext("?");
  
        numeric Step ; Step := 2cm div bbwidth(PicB)  ;
  
        for i = 1 upto Step :
           draw PicB shifted (i*5mm,0) ;
        endfor ;
        draw PicA ;
     \stopMPpage
  \stoptext
  

  Gives:

• 

What you get is 15 "?" but no "*"!

In order to get this corrected one needs to calculate the boundingbox of the "?" on beforehand. Hans Hagen provided this solution on 14-10-2014.

• \starttext
     \startMPcalculation
         path PicX ; PicX := boundingbox textext("?") ;
     \stopMPcalculation
  
     \startMPpage
        picture PicA ; PicA := textext("*");
        picture PicB ; PicB := textext("?");
  
        numeric Step ; Step := 2cm div bbwidth(PicX) ;
        % numeric Step ; Step := 2cm div bbwidth(PicB)  ;
  
        for i = 1 upto Step :
           draw PicB shifted (i*5mm,0) ;
        endfor ;
        draw PicA ;
     \stopMPpage
  \stoptext
  
  

  Gives:

• 

Now you get 14 "?" and the "*".

A Full Example

• \setupbodyfont [8pt]
  
  \defineoverlay[Myframe][\reuseMPgraphic{Frame}]
  
  \setuppapersize[A8][A8]
  
  \setuplayout
     [topspace=5mm,
      backspace=5mm,
      height=middle,
      width=middle,
      header=0pt,
      footer=0pt]
  
  \starttext
  
  % ======== Definition of the frame in Metafun ==========
  \startMPcalculation
     path PicX ; PicX := boundingbox textext("= : =") ;
  \stopMPcalculation	
     
  \startreusableMPgraphic{Frame}
     numeric u,v,xshift,yshift,picwidth,remnant,nelements;
  
     u := OverlayWidth;
     v := OverlayHeight;
          
     path p,w;
     p := unitsquare xscaled u yscaled v;
     w := fullcircle scaled 8pt;
  	
     picture Edgepic,Linepic[];
    
     color edgedotcolor,linelementcolorA;
    
     edgedotcolor       := blue;
     linelementcolorA := red;
  
     Linepic[1] := textext("\rotate[rotation=90]{= : =}");
     Linepic[2] :=  textext("= : =");
     Edgepic    := textext("o");
  	
     %Calculations for the horizontal frame-element placement:
       % In order to make this work, the width of the line element needs to be calculated on beforehand.
       % path PicX; PicX := textext(")(");
     picwidth    := bbwidth(PicX);
     nelements := u div picwidth;
     remnant    := u mod picwidth;
     xshift        := picwidth + remnant/nelements;	 
  
     Linepic[3] := Linepic[2] shifted (0.5*picwidth,0);
  
     for a = llcorner p, ulcorner p :
        for i = 1 upto nelements :
           draw Linepic[3] shifted ((xpart a + (i-1)*xshift),ypart a) withcolor linelementcolorA;
        endfor;
     endfor;
  	 			
     %Calculations for the vertical frame-element placement:
     picheight   := bbwidth(PicX);
     nelements := v div picheight;
     remnant    := v mod picheight;
     yshift        := picheight + remnant/nelements;
  	 
     Linepic[4]:= Linepic[1] shifted (0,0.5*picheight);
  	 
     for a = llcorner p, lrcorner p :
        for i = 1 upto nelements:
           draw Linepic[4] shifted (xpart a,ypart a + (i-1)*yshift) withcolor linelementcolorA;
        endfor;
     endfor;
  
     for i = llcorner p, lrcorner p,ulcorner p,urcorner p :
        fill w shifted (xpart i,ypart i) withcolor white;
          draw Edgepic shifted (xpart i,ypart i) withcolor edgedotcolor;
     endfor;
  
  % For frame-element positioning checking:
  %   draw p;
  %
  \stopreusableMPgraphic
  
  % ==========
  
  \startframedtext
     [width=0.8\textwidth,height=0.8\textheight,frame=off,background=Myframe, align={middle,lohi}]
        The butterfly counts not months but moments, and has time enough.
        \blank
        {\tfx Rabindranath Tagore}
  \stopframedtext
  \stoptext
  
  

  Gives:

• 

There is one important remark: The MPcalculation and the drawing itself must be inside \starttext ... \stoptext.