path: root/fonts/xq/xqhints.mf

%this is xqhints.mf - the original name of that file was hints.mf, it was 
%renamed for the reason of significance.




% hints.mf --- an attempt at PostScript Type-1 Hints in METAFONT for use
%              with PS2MF.
%
% Copyright (c) 1992 I. Lee Hetherington, all rights reserved.  I have
% not yet decided on what copyright restrictions I will place here.
% Probably something like TeX's copyright.  I think the GNU copyleft
% is far too extreme.
%
% The general scheme for hint implementation is apply vertical (hstem)
% and horizontal (vstem) hints separately.  For each direction, we
% first collect the stems in a sorted list.  At this point we reject
% overlapping or duplicate stems.  When we first need to use the
% hints, we make sure that piecewise linear transformations are
% computed.  These METAFONT transformations depend on the stem or
% inter-stem region a particular x- or y-coordinate falls in.  These
% transformations are easily computed once the stems specified in
% character space are placed in pixel space.  This stem placement is
% more complicated in the vertical direction because of the BlueValues
% font-level hints.
%
% Currently the implemented hints are BlueValues, OtherBlues,
% BlueScale, BlueShift, BlueFuzz, hstem, hstem3, vstem, vstem3, `Hint
% Replacement', and `Flex'.  The hints FamilyBlues, FamilyOtherBlues
% are not implemented as we only apply hints at the font and character
% level, not across an entire font family.  The hints StdHW, StdVW,
% StemSnapH, and StemSnapV are not implemented.  It would probably not
% be very difficult to add these.  The ForceBold, LanguageGroup,
% RndStemUp, and ExpansionFactor are also not implemented.
%
% Hint replacement ignores previous stem hints unless the same stem
% was used previously.  In this case, the stem is placed the same as
% it was before.  If after replacement a single stem is respecified
% without the other original stems, we can place it as it was placed
% before.  However, *both* edges of the stem must be identical.  This
% may now be irrelevant since stems are placed independently now
% (except in the case of hstem3 and vstem3, of course).
%
% I make no claim to that these hints have exactly the same effect as
% Adobe PostScript font rasterizer.  The hints and their interactions
% can be quite complicated.  The hint implementation in this file is
% based solely on my interpretation of their effects given their
% description in the book "Adobe Type 1 Font Format, Version 1.1".
%
% There is certainly room for improvement: both with respect to hint
% effects and implementation efficiency.  Running METAFONT can take
% quite a while.  I've made some attempt at caching placement results
% using METAFONT vector to reduce redundant computation.  One
% improvement I can think of is replacing the stem gathering and
% sorting (h_insert and v_insert) with C code in PS2MF.  Another is
% predetermining which stems are effected by the blue values.  Most of
% the other placement/transformation opertions need to be done in
% METAFONT because these operations are dependent on device resolution
% and magnification.
%
% I welcome comments, suggestions, fixes, and improvements.  I plan on
% commenting this code more when I get a chance.  The comments are
% pretty sparse at the moment.
%
% If you want to disable the hint mechanism, specify `hinting:=0'
% before this file is included.  METAFONT will run much faster but
% will produce inconsistent stem widths at low resolutions.  At higher
% resolutions these hints are much less important.
%
% 1.0 beta     3/30/92   I. Lee Hetherington (ilh@lcs.mit.edu)

if unknown hinting: hinting := 1; fi

% expansion and slanting (same as `xscaled expansion slanted slanting')
if unknown expansion: expansion := 1; fi
if unknown slanting: slanting := 0; fi

% make sure character space units are defined
if unknown FX#: FX# := 0.001pt#; fi
if unknown FY#: FY# := 0.001pt#; fi
FX# := FX# * expansion; % incorporate expansion here so hints know about it
u# := FX#;
v# := FY#;
define_pixels(u,v,FX,FY);

boolean debug; debug := false;

% like round but rounds to the nearest half
def roundhalf(expr x) = (round(x+0.5)-0.5) enddef;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% horizontal (vstem) hints

extra_beginchar := extra_beginchar & "h_init;numeric h[][]sc;";

% initialize structures
def h_init =
  numeric h.r,h[]s,h[]p,h[]pc;
  boolean h.triple;
  transform h[]t;
  h.r := 1;
  h.triple := false;
enddef;

% insert new stem into sorted list
% requires that stems don't overlap
% toss duplicates
def h_insert(expr a, b) =
  boolean flag; flag:=false; % temporary flag to exit loop
  if h.r = 1: % no stems thus far
    h[1]s := a;
    h[2]s := b;
    h.r := 3;
  elseif a > h[h.r-1]s: % at end
    h[h.r]s := a;
    h[h.r+1]s := b;
    h.r := h.r + 2;
  else: % we need to search for location and shift elements
    for i = 1 step 2 until h.r-2:
      exitif ((h[i]s >= a) and (h[i]s <= b)) or
             ((h[i+1]s >= a) and (h[i+1]s <= b));
      if a < h[i]s:
        % insert here, so shift remaining elements up by two
        for j = h.r-1 downto i:
          h[j+2]s := h[j]s;
        endfor
        h[i]s := a;
        h[i+1]s := b;
        h.r := h.r + 2;
	flag := true;
      fi
      exitif flag;
    endfor
  fi
enddef;

% horizontal stem width (for vstem's)
def hsw(expr a,b) = max(1, round(abs(a-b)*u)) enddef;

% place stems in pixel space
def h_place =
  if h.triple:
    h2p - h1p = vsw(h1s, h2s) - 1;
    h4p - h3p = vsw(h3s, h4s) - 1;
    h6p - h5p = vsw(h5s, h6s) - 1;
    if unknown h[h1s][h2s]sc: % cached?
      h3p - h2p = h5p - h4p;
      h1p = roundhalf(h1p - (0.5[h1p,h2p] - 0.5[h1s,h2s]*u));
      h3p = roundhalf(h3p - (0.5[h3p,h4p] - 0.5[h3s,h4s]*u));
      h[h1s][h2s]sc := h1p;
      h[h3s][h4s]sc := h3p;
      h[h5s][h6s]sc := h5p;
    else:
      h1p = h[h1s][h2s]sc;
      h3p = h[h3s][h4s]sc;
      h5p = h[h5s][h6s]sc;
    fi
  elseif h.r > 1:
    for i = 1 step 2 until h.r-2:
      h[i+1]p - h[i]p = hsw(h[i]s,h[i+1]s) - 1;
      if unknown h[h[i]s][h[i+1]s]sc: % cached?
        h[i]p = roundhalf(h[i]p - (0.5[h[i]p,h[i+1]p] - 0.5[h[i]s,h[i+1]s]*u));
        h[h[i]s][h[i+1]s]sc := h[i]p;
      else:
        h[i]p = h[h[i]s][h[i+1]s]sc;
      fi
    endfor
  fi
  if debug:
    for i = 1 upto h.r-1:
      message "h" & decimal(i) & ": " & decimal(h[i]s) &
              " (" & decimal(h[i]p) & ")";
    endfor
  fi
enddef;

% build separate transformations for each region
def h_transforms =
  if unknown h1p: h_place; fi
  if h.r = 1: h[0]t := identity xscaled u;
  else:
    % first region (not stem)
    h[0]t := identity shifted (-h[1]s,0)
                      xscaled u
                      shifted (h[1]p,0);
    % last region (not stem)
    h[h.r-1]t := identity shifted (-h[h.r-1]s,0)
                          xscaled u
                          shifted (h[h.r-1]p,0);
    % other regions
    for i = 1 upto h.r - 2:
      h[i]t := identity shifted (-h[i]s,0)
                        xscaled
                        (if h[i+1]p = h[i]p: 0
                         else: ((h[i+1]p - h[i]p) / (h[i+1]s - h[i]s)) fi)
                        shifted (h[i]p,0);
    endfor
  fi
  if debug:
    for i = 0 upto h.r-1:
      show xxpart h[i]t;
    endfor
  fi
enddef;

% find region according to x-coordinate
def h_region(expr x) =
  if h.r = 1: 0
  elseif x < h[1]s: 0
  elseif x >= h[h.r-1]s: (h.r - 1)
  else:
    for i = 2 upto h.r-1:
      if x < h[i]s: (i - 1) fi
      exitif (x < h[i]s);
    endfor
  fi
enddef;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% vertical (hstem) hints with support for BlueValues, OtherBlueValues,
% BlueScale, BlueShift, and BlueFuzz

extra_beginchar := extra_beginchar & "v_init;numeric v[][]sc;";

% initialize structures
def v_init =
  numeric v.r,v[]s,v[]p,v[]pc;
  boolean v.triple;
  transform v[]t;
  v.r := 1;
  v.triple := false;
enddef;

% insert new stem into sorted list
% requires that stems don't overlap
def v_insert(expr a, b) =
  boolean flag; flag:=false; % temporary flag to exit loop
  if v.r = 1: % no stems thus far
    v[1]s := a;
    v[2]s := b;
    v.r := 3;
  elseif a > v[v.r-1]s: % at end
    v[v.r]s := a;
    v[v.r+1]s := b;
    v.r := v.r + 2;
  else: % we need to search for location and shift elements
    for i = 1 step 2 until v.r-2:
      exitif ((v[i]s >= a) and (v[i]s <= b)) or
             ((v[i+1]s >= a) and (v[i+1]s <= b));
      if a < v[i]s:
        % insert here, so shift remaining elements up by two
        for j = v.r-1 downto i:
          v[j+2]s := v[j]s;
        endfor
        v[i]s := a;
        v[i+1]s := b;
        v.r := v.r + 2;
	flag := true;
      fi
      exitif flag;
    endfor
  fi
enddef;

% Blue stuff
boolean suppress; % suppress overshoot
suppress := v < blue_scale;

def find_bot_blue(expr y) =
  numeric blue.pos, blue.over;
  for i = 1 upto bot_blues.n:
    exitif known blue.pos;
    if (y >= bot_blues[i]o - blue_fuzz) and (y <= bot_blues[i]p):
      blue.pos := bot_blues[i]p;
      blue.over := bot_blues[i]o;
    fi
  endfor
enddef;

def find_top_blue(expr y) =
  numeric blue.pos, blue.over;
  for i = 1 upto top_blues.n:
    exitif known blue.pos;
    if (y >= top_blues[i]p) and (y <= top_blues[i]o + blue_fuzz):
      blue.pos := top_blues[i]p;
      blue.over := top_blues[i]o;
    fi
  endfor
enddef;

% vertical stem width (for hstem's)
def vsw(expr a,b) = max(1, round(abs(a-b)*v)) enddef;

% place stems in pixel space paying attention to blue stuff
% (currently ignore v.triple)
% CHECK CACHING IN HERE.  MIGHT NOT NEED TO DO BLUE STUFF SO OFTEN
def v_place =
  if v.triple: % ignore blue stuff for hstem3
    v2p - v1p = vsw(v1s, v2s) - 1;
    v4p - v3p = vsw(v3s, v4s) - 1;
    v6p - v5p = vsw(v5s, v6s) - 1;
    if unknown v[v1s][v2s]sc: % cached?
      v3p - v2p = v5p - v4p;
      v1p = roundhalf(v1p - (0.5[v1p,v2p] - 0.5[v1s,v2s]*v));
      v3p = roundhalf(v3p - (0.5[v3p,v4p] - 0.5[v3s,v4s]*v));
      v[v1s][v2s]sc := v1p;
      v[v3s][v4s]sc := v3p;
      v[v5s][v6s]sc := v5p;
    else:
      v1p = v[v1s][v2s]sc;
      v3p = v[v3s][v4s]sc;
      v5p = v[v5s][v6s]sc;
    fi
  elseif v.r > 1:
    for i = 1 step 2 until v.r-2:
      find_bot_blue(v[i]s);
      if known blue.pos:
        % position according to blue values
        if suppress:
          v[i]p = roundhalf(blue.pos * v);
        else:
          v[i]p = roundhalf(blue.pos * v) -
                  max(if v[i]s <= blue.pos-blue_shift: 1 else: 0 fi,
                      round((blue.pos - if v[i]s < blue.over: blue.over
                                        else: v[i]s fi)*v));
        fi
        v[i+1]p = v[i]p + vsw(v[i]s,v[i+1]s) - 1;
      fi
      find_top_blue(v[i+1]s);
      if known blue.pos:
        % position according to blue values
        if suppress:
          v[i+1]p := roundhalf(blue.pos * v);
        else:
          v[i+1]p := roundhalf(blue.pos * v) +
                     max(if v[i+1]s >= blue.pos+blue_shift: 1 else: 0 fi,
                         round((if v[i+1]s > blue.over: blue.over
                                else: v[i+1]s fi - blue.pos)*v));
        fi
        % Note that it is possible for the top of a stem to be fall in a
        % top zone and the bottom to fall in a bottom zone.  Therefore, only
        % set v[i]p (bottom) if it wasn't set previously.
        if unknown v[i]p: v[i]p := v[i+1]p - (vsw(v[i]s,v[i+1]s) - 1); fi
      fi
    endfor
    % place remaining stems if not under blue control
    for i = 1 step 2 until v.r-2:
      if unknown v[i]p:
        v[i+1]p = v[i]p + vsw(v[i]s,v[i+1]s) - 1;
        if unknown v[v[i]s][v[i+1]s]sc: % cached?
          v[i]p = roundhalf(v[i]p - (0.5[v[i]p,v[i+1]p] - 0.5[v[i]s,v[i+1]s]*v));
          v[v[i]s][v[i+1]s]sc := v[i]p;
        else:
          v[i]p = v[v[i]s][v[i+1]s]sc;
        fi
      fi
    endfor
  fi
  if debug:
    for i = 1 upto v.r-1:
      message "v" & decimal(i) & ": " & decimal(v[i]s) &
              " (" & decimal(v[i]p) & ")";
    endfor
  fi
enddef;

% build separate transformations for each region
def v_transforms =
  if unknown v1p: v_place; fi
  if v.r = 1: v[0]t := identity yscaled v;
  else:
    % first region (not stem)
    v[0]t := identity shifted (0,-v[1]s)
                      yscaled v
                      shifted (0,v[1]p);
    % last region (not stem)
    v[v.r-1]t := identity shifted (0,-v[v.r-1]s)
                          yscaled v
                          shifted (0,v[v.r-1]p);
    % other regions
    for i = 1 upto v.r - 2:
      v[i]t := identity shifted (0,-v[i]s)
                        yscaled
                        (if v[i+1]p = v[i]p: 0
                         else: ((v[i+1]p - v[i]p) / (v[i+1]s - v[i]s)) fi)
                        shifted (0,v[i]p);
    endfor
  fi
  if debug:
    for i = 0 upto v.r-1:
      show yypart v[i]t;
    endfor
  fi
enddef;

% find region according to y-coordinate
def v_region(expr y) =
  if v.r = 1: 0
  elseif y < v[1]s: 0
  elseif y >= v[v.r-1]s: (v.r - 1)
  else:
    for i = 2 upto v.r-1:
      if y < v[i]s:
        (i - 1)
      fi
      exitif (y < v[i]s);
    endfor
  fi
enddef;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% actual pair (point) and path transformations

% transform a pair (point) to pixel space, caching x and y coordinates
% separately for future use
def hv_pixel(expr p) =
  if unknown h[xpart p]pc:
    hide(h[xpart p]pc := xpart(p transformed h[h_region(xpart p)]t))
  fi
  if unknown v[ypart p]pc:
    hide(v[ypart p]pc := ypart(p transformed v[v_region(ypart p)]t))
  fi
  (h[xpart p]pc, v[ypart p]pc)
enddef;    

% do the region-dependent tranformation on a point or path
def hv_transform(expr p) =
  if unknown v0t: hide(v_transforms) fi
  if unknown h0t: hide(h_transforms) fi
  if pair p: hv_pixel(p)
  else: % path
    for i = 0 upto length p - 1:
       hv_pixel(point i of p) .. controls
       hv_pixel(postcontrol i of p) and hv_pixel(precontrol i+1 of p) .. 
    endfor
    hv_pixel(point (length p) of p)
  fi
enddef;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% proofing stuff -- display stem hints on proof sheets

% Mark a vstem specified in character space.  Note that the hints aren't known
% at this time so they can't be applied to the stem.
def mark_vstem(expr a,b) =
  one := h + 20;
  two := -d - 20;
  aa := round(a*u);
  bb := round(b*u);
  proofrule((aa,two),(aa,one)); proofrule((bb,two),(bb,one));
  if proofing>3:
    screenrule((aa,two),(aa,one)); screenrule((bb,two),(bb,one)); fi
enddef;

% Mark a hstem specified in character space.  Note that the hints aren't known
% at this time so they can't be applied to the stem.
def mark_hstem(expr a,b) =
  one := -20;
  two := w + 20;
  aa := round(a*v);
  bb := round(b*v);
  proofrule((one,aa),(two,aa)); proofrule((one,bb),(two,bb));
  if proofing>3:
    screenrule((one,aa),(two,aa)); screenrule((one,bb),(two,bb)); fi
enddef;

% Mark blue value ranges.
def mark_blues =
  for i = 1 upto top_blues.n:
    one := -30;
    two := w + 30;
    aa := round(top_blues[i]o*v);
    bb := round(top_blues[i]p*v);
    proofrule((one,aa),(two,aa)); proofrule((one-10,bb),(two+10,bb));
    if proofing>3:
      screenrule((one,aa),(two,aa)); screenrule((one,bb),(two,bb)); fi
  endfor
  for i = 1 upto bot_blues.n:
    one := -30;
    two := w + 30;
    aa := round(bot_blues[i]o*v);
    bb := round(bot_blues[i]p*v);
    proofrule((one,aa),(two,aa)); proofrule((one-10,bb),(two+10,bb));
    if proofing>3:
      screenrule((one,aa),(two,aa)); screenrule((one,bb),(two,bb)); fi
  endfor
enddef;
extra_beginchar := extra_beginchar & "mark_blues;";


numeric subpath_label; subpath_label := ASCII "a";
extra_beginchar := extra_beginchar &
                   "subpath_label:=ASCII " & ditto & "a" & ditto & ";";

% Mark path points.  If p is a pair (point) then it is a control point.
% Control points are only plotted if proofing > 2, but they are left
% unlabelled.
def mark_points(expr p) =
  if path p:
    for i = 0 upto length p:
      makelabel(char(subpath_label) & decimal(i), point i of p);
    endfor
    if proofing > 2: % plot control points too
      for i = 1 upto length p - 1:
        makelabel("", postcontrol i of p);
        makelabel("", precontrol i of p);
      endfor
      makelabel("", postcontrol 0 of p);
      makelabel("", precontrol (length p - 1) of p);
    fi
    subpath_label:=subpath_label+1;
  elseif (pair p) and (proofing>2): makelabel("", p)
  fi
enddef;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% macros used in character descriptions

% store hint commands in this string for future incorporation
string delayed_hints; delayed_hints:="";

% specify delayed hints
def dh(expr s) =
  if hinting>0: hide(delayed_hints := delayed_hints & s & ";") fi
enddef;

% incorporate delayed hints
def ih =
  if hinting>0: hide(h_init; v_init; scantokens delayed_hints;
                     delayed_hints:="") fi
enddef;

% vertical stem hint
def vs(expr a,b) =
  if hinting>0: hide(h_insert(a,b); if proofing>0: mark_vstem(a,b); fi) fi
enddef;

% vstem3 indicator
def vst = if hinting>0: hide(h.triple:=true) fi enddef;

% horizontal stem hint
def hs(expr a,b) =
  if hinting>0: hide(v_insert(a,b); if proofing>0: mark_hstem(a,b); fi) fi
enddef;

% hstem3 indicator
def hst = if hinting>0: hide(v.triple:=true) fi enddef;

% apply hints
def ah(expr p) =
  hide(if proofing>0:
         if hinting>0: mark_points(hv_transform(p));
         else: mark_points(p xscaled u yscaled v); fi
       fi)
  if hinting>0: hv_transform(p)
  else: (p xscaled u yscaled v) fi
enddef;

% line to
def lt(expr a,b) =
  -- (a,b)
enddef;

% line to (after hint replacement)
def lth(expr a,b) =
  -- ih ah((a,b)
enddef;

% curve to
def ct(expr a,b,c,d,e,f) =
  .. controls (a,b) and (c,d) .. (e,f)
enddef;

% curve to (after hint replacement)
def cth(expr a,b,c,d,e,f) =
  .. controls ah((a,b)) and ih ah((c,d)) .. ah((e,f)
enddef;

% flex
def fl(expr rx,ry,ax,ay,bx,by,cx,cy,dx,dy,ex,ey,fx,fy,height) =
  if (abs((rx,ry) - (cx,cy))*u >= 0.01*height): % use curves
    ct(ax,ay,bx,by,cx,cy)
    ct(dx,dy,ex,ey,fx,fy)
  else:
    lt(fx,fy) % replace curves with line
  fi
enddef;

% flex (after hint replacement)
def flh(expr rx,ry,ax,ay,bx,by,cx,cy,dx,dy,ex,ey,fx,fy,height) =
  if (abs((rx,ry) - (cx,cy))*u >= 0.01*height): % use curves
    cth(ax,ay,bx,by,cx,cy)
    ct(dx,dy,ex,ey,fx,fy)
  else:
    lth(fx,fy) % replace curves with line
  fi
enddef;

% close path
def cp = -- cycle enddef;

% Draw by filling and stroking the path (helps greatly with small sizes).
% We specify slanting here but not expansion because that's already been
% incorporated.
def dr expr c =
  addto currentpicture contour (c slanted slanting) withpen pencircle;
enddef;

picture chp[];

% seac (standard encoding accented character) use previously created
% pictures.  When specifying accent shift, use slanting to correctly
% position accent.
def seac(expr achar,bchar,adx,ady) =
  currentpicture := chp[bchar] +
      chp[achar] shifted ((adx*u, ady*v) slanted slanting);
enddef;

% non-zero winding rule for filling instead of default positive rule
def nonzerowinding = cull currentpicture dropping (0,0); enddef;
extra_endchar := extra_endchar & "nonzerowinding;";

turningcheck := 0; % no checking because directions are known

autorounding := smoothing := 0; % we're doing hints ourselves