%%% textpath.mp
%%% Copyright 2007 Stephan Hennig <[email protected]>
%
% This work may be distributed and/or modified under the conditions of
% the LaTeX Project Public License, either version 1.3 of this license
% or (at your option) any later version.  The latest version of this
% license is in http://www.latex-project.org/lppl.txt
%

if known textpath_fileversion: endinput fi;
string textpath_fileversion;
textpath_fileversion := "v1.6 (2007/02/11)";
message "Loading textpath " & textpath_fileversion;


%%% Global variables.

%%% Global variable.
%%% Character coordinates that lay outside path boundaries after
%%% transformation are clipped to the boundaries.
%%% Variable textpathClip determines if such characters should be
%%% output at path boundaries, thereby acting as a visual indicator
%%% that something went wrong, or if text outside path boundaries
%%% should be omitted. Variable textpathClip can be either one (omit)
%%% or zero (don't omit).
newinternal textpathClip;
textpathClip := 0;

%%% Global variable.
%%% Variable textpathLetterSpace determines the amount of space that
%%% is additionally inserted between all characters.  This can be
%%% useful, when drawing text along a concacve shape or in general
%%% along paths with a high curvature.  Variable textpathLetterSpace
%%% can contain positive or negative values.
newinternal textpathLetterSpace;
textpathLetterSpace := 0bp;

%%% Global variable.
newinternal textpathRotation;
textpathRotation := 0;

%%% Global variable.
newinternal textpathAbsRotation;
textpathAbsRotation := 0;

newinternal textpathRepeat;
textpathRepeat := 1;

newinternal textpathStretch;
textpathStretch := 1;

newinternal textpathHSpace;
textpathHSpace := 0;

newinternal textpathShift;
textpathShift := 0;

newinternal textpathSoulLetterSpace;
textpathSoulLetterSpace := 10bp;

newinternal textpathFancyStrokes;
textpathFancyStrokes := 1;

newinternal textpathStrokePrecision;
textpathStrokePrecision := 10;

newinternal textpathCureSqrt;
textpathCureSqrt := 1;

newinternal textpathAutoScale;
textpathAutoScale := 0;

newinternal textpathDraft;
textpathDraft := 0;

newinternal textpathDebug;
textpathDebug := 1;

pair textpathHookCoord, textpathHookPoint;
newinternal textpathHookRot;
textpathHookCoord := origin;
textpathHookPoint := origin;
textpathHookRot := 0;



%%% User Macros.

%%% User macro.
%%% Set text along a path.
%%% Parameters:
%%%  * a text string t that is fed into TeX through latexmp,
%%%  * a path p the text should follow.
%%%  * a numeric variable j that controls justification:
%%%    j=0:   text is left aligned on the path,
%%%    j=0.5: text is centered on the path,
%%%    j=1:   text is right aligned on the path,
%%%    The general rule is the character at fraction j of the total
%%%    text width is transformed to the point at fraction j of the total
%%%    path width.  j should be from the interval [0, 1].
%%% Return value:
%%%  * a picture variable containing text following a path.
def textpath(expr t, p, j)=
 textpathFont("", t, p, j)
enddef;


%%% User macro.
%%% Set text in arbitrary font along a path.
%%% Parameters:
%%%  * a string f that is a valid LaTeX font selection command, e.g., \itshape,
%%%  * a text string t that is fed into TeX through latexmp,
%%%  * a path p the text should follow.
%%%  * a numeric variable j that controls justification:
%%%    j=0:   text is left aligned on the path,
%%%    j=0.5: text is centered on the path,
%%%    j=1:   text is right aligned on the path,
%%%    The general rule is the character at fraction j of the total
%%%    text width is transformed to the point at fraction j of the total
%%%    path width.  j should be from the interval [0, 1].
%%% Return value:
%%%  * a picture variable containing text following a path.
vardef textpathFont(expr f, t, p, j)=
save pre, post;
string pre, post;
 pre := f & "\spaced{";
 post := "}";
 textpathToPic(strToPic(pre & t & post), p, j)
enddef;


%%% User macro.
%%% Set text along a path.
%%% Parameters:
%%%  * a text string t that is fed into TeX through latexmp,
%%%  * a path p the text should follow.
%%%  * a numeric variable j that controls justification:
%%%    j=0:   text is left aligned on the path,
%%%    j=0.5: text is centered on the path,
%%%    j=1:   text is right aligned on the path,
%%%    The general rule is the character at fraction j of the total
%%%    text width is transformed to the point at fraction j of the total
%%%    path width.  j should be from the interval [0, 1].
%%% Return value:
%%%  * a picture variable containing text following a path.
vardef textpathRaw(expr t, p, j)=
save pre, post;
string pre, post;
 pre := "\rule[-30bp]{0pt}{30bp}";
 post := "";
 textpathRawToPic(strToPic(pre & t & post), p, j)
enddef;



%%% Internal Macros.

%%% Internal macro.
%%% Convert a string into a picture using TeX via latexmp package.
%%% Parameters:
%%%  * a string.
%%% Return value:
%%%  * a picture variable.
vardef strToPic(expr s)=
interim labeloffset := 0bp;
 thelabel.urt(textext(s), origin)
enddef;


%%% Internal macro.
%%% Computes the length of a textual picture, thereby correcting
%%% for textpathSoulLetterSpace and textpathLetterSpace
vardef getPictureWidth(expr textpic, scale)=
save lenpic, k, w;
numeric lenpic, k, w;
 lenpic := 0;
 k := 0;
 for item within textpic:
   if textual item:
     w := xpart lrcorner ( item shifted (scale*k*(textpathLetterSpace-textpathSoulLetterSpace), 0bp) );
     if w > lenpic:
       lenpic := w;
     fi
     k := k + 1;
   fi
 endfor
 lenpic
enddef;


%%% Internal macro.
%%% Does pre-processing for macros textpath(Raw)ToPic, such as
%%% calculating variables startOffset, autoScale, ltextpathHSpace etc.
def preprocessTextPic(expr rawMode, atextpic, p, j)=
 save textpic, pic, lenp, lenpic, startOffset, ltextpathHSpace, autoScale, overfullPath;
 interim bboxmargin := 0bp;
 numeric lenp, lenpic, startOffset, ltextpathHSpace, autoScale;
 picture textpic, pic;
 boolean overfullPath;

 textpic := atextpic;
 pic := nullpicture;
%%% Compute path length.
 lenp := arclength(p);
%%% Compute picture length, i.e., correct plain picture dimensions
%%% for soul and textpath letter spacing.
 if rawMode:%%% Called from textpathRawToPic.
   lenpic := xpart (lrcorner textpic - llcorner textpic);
 else:%%% Called from textpathToPic.
   lenpic := getPictureWidth(textpic, 1);%%% Get corrected picture with scale = 1.
 fi
%%% Compute inter-copy space (for textpathRepeat > 1).
 if textpathStretch = 0:
   ltextpathHSpace := textpathHSpace;
 else:
   ltextpathHSpace := lenp/textpathRepeat - lenpic;
 fi
%%% Compute startOffset as j * remaining space.
 startOffset := j * (lenp - textpathRepeat*lenpic - (textpathRepeat-1)*ltextpathHSpace);
%%% By default, assume path isn't overfull.
 overfullPath := false;
 autoScale := 1;
%%% Overfull path?
 if startOffset < 0:
   overfullPath := true;
   if textpathAutoScale <> 0:%%% Calculate scaling factor.
     if textpathStretch <> 0:
       ltextpathHSpace := 0;%%% No inter-copy space when stretching allowed.
     fi
     autoScale := lenp/(textpathRepeat*lenpic + (textpathRepeat-1)*ltextpathHSpace1);
     startOffset := 0;
     if textpathDraft = 0:
       textpic := atextpic scaled autoScale;
     else:
       textpic := atextpic xscaled autoScale;%%% Don't scale y in draft mode.
     fi
     lenpic := getPictureWidth(textpic, autoScale);
%%% Compute inter-copy space (for textpathRepeat > 1).
     if textpathStretch = 0:
       ltextpathHSpace := textpathHSpace*autoScale;
     else:
       ltextpathHSpace := lenp/textpathRepeat - lenpic;%%% Should be equal to zero.
     fi
%%% Finally, output a warning.
     message "Package textpath warning:  Overfull path!  Scaled to " & decimal autoScale & ".";
   else:%%% No scaling.
     autoScale := 1;
     if textpathClip = 0:%%% Warn the user about overfull paths.
       message "Package textpath warning:  Overfull path!  Not clipped.";
     else:
       message "Package textpath warning:  Overfull path!  Clipped.";
     fi
   fi
 fi
enddef;



%%% Internal macro.
def transformSimpleItem(expr rawMode, item, p)=
%%% bitem is a character or straight rule to transform.
%%% banker is its original anchor position.
 if rawMode:
   bitem := item;
   banker := (xpart center bitem, autoScale*30bp);%%% Why 30bp?
 else:
   bitem := item shifted (k*autoScale*(textpathLetterSpace-textpathSoulLetterSpace), 0bp);
   banker := (xpart center bitem, ypart item);
 fi
%%% bx is the anchor position of a first item copy.
 bx := (xpart banker) + startOffset;
%%% Shift anchor to origin and raise baseline.
 bitem := bitem shifted -banker shifted (0bp, textpathShift);
%%% Iterate over all copies of an item.
 for i=1 upto textpathRepeat:
%%% cx is the anchor position of an item copy.
   cx := (i-1)*(lenpic + ltextpathHSpace) + bx;
%%% Draw items with valid positions or if no clipping.
   if ((cx>=0) and (cx<=lenp)) or (textpathClip=0):
%%% Compute path time value.
     tb := arctime cx of p;
%%% Compute rotation angle.
     if textpathAbsRotation=0:
       db := textpathRotation + angle direction tb of p;
     else:
       db := textpathRotation;
     fi
%%% Draw item's bounding box?
     if odd (textpathDebug div 2):
       addto pic doublepath bbox bitem rotated db shifted point tb of p withpen currentpen;
     fi
%%% Draw item?
     if odd (textpathDebug div 1):
%%% In draft mode fill bounding box if path is overfull.
       if overfullPath and (textpathDraft<>0):
         addto pic contour bbox bitem rotated db shifted point tb of p;
       else:
         addto pic also bitem rotated db shifted point tb of p;
       fi
     fi
%%% Draw item's anchor point?
     if odd (textpathDebug div 4):
       addto pic contour fullcircle scaled 3bp shifted point tb of p;
     fi
   fi
 endfor
%%% Save top right corner of supported square root glyphs in variable textpathHookCoord.
 if rawMode and (textpathCureSqrt <> 0):
   if ((fontpart item="cmex10")      and ((ASCII textpart item>=112) and (ASCII textpart item<=116))) or
     ((fontpart item="cmsy5")       and (ASCII textpart item=112)) or
     ((fontpart item="cmsy6")       and (ASCII textpart item=112)) or
     ((fontpart item="cmsy7")       and (ASCII textpart item=112)) or
     ((fontpart item="cmsy8")       and (ASCII textpart item=112)) or
     ((fontpart item="cmsy9")       and (ASCII textpart item=112)) or
     ((fontpart item="cmsy10")      and (ASCII textpart item=112)) or
     ((fontpart item="cmbsy10")     and (ASCII textpart item=112)) or
     ((fontpart item="fourier-mex") and (ASCII textpart item=114)) or
     ((fontpart item="fourier-ms")  and (ASCII textpart item=112)) or
     ((fontpart item="MnSymbolE5")  and (ASCII textpart item=186)) or
     ((fontpart item="MnSymbolE5")  and (ASCII textpart item=189)) or
     ((fontpart item="MnSymbolE10")  and (ASCII textpart item=186)):%%% \sqrt glyph?
     textpathHookCoord := urcorner item shifted (-xpart center item, -autoScale*30bp + textpathShift);
     textpathHookRot := db;
     textpathHookPoint := point tb of p;
%       addto pic contour fullcircle scaled 2bp shifted textpathHookCoord rotated db shifted point tb of p withcolor green;
   else:
     textpathHookCoord := origin;
   fi
 fi
enddef;


%%% Internal macro.
def transformStrokedItem(expr rawMode, item, p)=
 if textpathFancyStrokes = 0:
   transformSimpleItem(true, item, p);
 else:
   pp := pathpart item;
   for i=1 upto textpathRepeat:
     if (textpathHookCoord=origin) or (textpathCureSqrt=0):
       banker := (0, ypart point 0 of pp - autoScale*30bp + textpathShift);
       bx := (xpart point 0 of pp) + startOffset;
       dpp := angle direction 0 of pp;
       cx := (i-1)*(lenpic + ltextpathHSpace) + bx;
       tb := arctime cx of p;
       if textpathAbsRotation=0:
         db := textpathRotation + angle direction tb of p;
       else:
         db := textpathRotation;
       fi
       np := banker rotated db shifted point tb of p%{dir (dpp+db)}
     elseif textpathCureSqrt=1:
       np := textpathHookCoord shifted (dir(-90)*xpart point 0 of makepath penpart item);
       np := np rotated textpathHookRot shifted textpathHookPoint%{dir textpathHookRot}
     fi
     for h=1 upto textpathStrokePrecision:
       hide(
         banker := (0, ypart point (h/textpathStrokePrecision) of pp - autoScale*30bp + textpathShift);
         bx := (xpart point (h/textpathStrokePrecision) of pp) + startOffset;
         cx := (i-1)*(lenpic + ltextpathHSpace) + bx;
         dpp := angle direction (h/textpathStrokePrecision) of pp;
         tb := arctime cx of p;
         if textpathAbsRotation=0:
           db := textpathRotation + angle direction tb of p;
         else:
           db := textpathRotation;
         fi
         )
       ..banker rotated db shifted point tb of p%{dir (dpp+db)}
     endfor;
     if odd (textpathDebug div 2):
       addto pic doublepath bbox np withpen currentpen;
     fi
     if odd (textpathDebug div 1):
       addto pic doublepath np withpen penpart item;
     fi
     if odd (textpathDebug div 4):
%%% Doesn't work.
%       addto pic contour fullcircle scaled 3bp shifted point tb of p;
     fi
   endfor
 fi
enddef;




%%% Internal working macro.
%%% Set text from picture variable along a path with justification j.
%%% Parameters:
%%%  * a picture that contains the text that has to be transformed onto a path,
%%%  * a path p the text should follow,
%%%  * a numeric variable that controls justification,
%%% Return value:
%%%  * a picture variable containing text following a path.
vardef textpathToPic(expr atextpic, p, j)=
 save bitem, banker, k, bx, cx, tb, db;
 numeric k, bx, cx, tb, db;
 picture bitem;
 pair banker;

 %%% Calculate variables such as startOffset, autoScale, ltextpathHSpace etc.
 preprocessTextPic(false, atextpic, p, j);
 %%%
 %%% Now iterate over all picture elements.
 %%%
 k := 0;
 for item within textpic:
   if textual item:%%% Process textual elements.
     transformSimpleItem(false, item, p);
     k := k + 1;
   else:
     message "Package textpath warning:  Unsupported picture element found!";
   fi
 endfor
 %%% Return pic.
 pic
enddef;



%%% Internal working macro.
%%% Set text from picture variable along a path with justification j.
%%% Parameters:
%%%  * a picture that contains the text that has to be transformed onto a path,
%%%  * a path p the text should follow,
%%%  * a numeric variable that controls justification,
%%% Return value:
%%%  * a picture variable containing text following a path.
vardef textpathRawToPic(expr atextpic, p, j)=
 save bitem, banker, bx, cx, tb, db, pp, np, dpp;
 numeric bx, cx, tb, db, dpp;
 picture bitem;
 pair banker;
 path pp, np;

 %%% Calculate variables such as startOffset, autoScale, ltextpathHSpace etc.
 preprocessTextPic(true, atextpic, p, j);
%%% Reset last sqrt glyph's top right bounding box corner.
 textpathHookCoord := origin;
 %%%
 %%% Now iterate over all picture elements.
 %%%
 for item within textpic:
   if textual item:%%% Process textual elements.
     transformSimpleItem(true, item, p);
   elseif stroked item:%%% Process stroked elements.
     transformStrokedItem(true, item, p);
   else:
     message "Package textpath warning:  Unsupported picture element found!";
   fi
 endfor
 pic
enddef;

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