% More-or-less general gray font generator
% See Appendix H of The METAFONTbook for how to use it

forsuffixes m = mag,rep:
 if unknown m: m := 1;
 elseif (m<1) or (m<>floor m):
  errmessage "Sorry, " & str m & " must be a positive integer";
  m := 1; fi endfor

mg := mag; mag := 1; mode_setup;
if mg>1: hppp := hppp*mg; vppp := vppp*mg;
 extra_endchar:=
  "if charcode>0:currentpicture:=currentpicture scaled mg;fi"
  & extra_endchar; fi;

if picture pix_picture: rep := 1;
 cull pix_picture keeping (1,infinity);
else: for z=(0,2),(1,0),(2,3),(3,1):
  fill unitsquare shifted z; endfor
 if not boolean lightweight: addto currentpicture also
  currentpicture rotated 90 xscaled -1; fi
 if unknown scale: scale := max(1,round(pixels_per_inch/300)); fi
 pix_wd := pix_ht := 4scale;
 if rep>1: picture pix;
   currentpicture := currentpicture shifted-(1,1); pix := currentpicture;
   for r=1 upto rep-1: addto currentpicture also pix shifted(4r,0); endfor
   cullit; pix := currentpicture;
   for r=1 upto rep-1: addto currentpicture also pix shifted(0,4r); endfor
   unfill unitsquare xscaled 4rep yscaled 2 shifted-(1,1);
   unfill unitsquare yscaled 4rep xscaled 2 shifted-(1,1); cullit; fi
 picture pix_picture; pix_picture := currentpicture scaled scale;
 pix_wd := pix_ht := 4scale*rep; fi

def # = *72.27/pixels_per_inch enddef;
if unknown dotsize: dotsize := 2.5pix_wd/rep; fi

beginchar(0,1.2dotsize#,1.2dotsize#,0);
fill fullcircle scaled dotsize scaled mg; endchar;

numeric a[]; newinternal b,k;
def next_binary =
 k := 0; forever: if k>b: a[incr b] := 0; fi
  exitif a[k]=0; a[k] := 0; k := k+1; endfor
 a[k] := 1 enddef;
def next_special_binary =
 if a[0]=1: for k=0 upto b: a[k] := 0; endfor a[incr b]
 else: k := 0; forever: exitif a[incr k]=1; endfor
  a[k-1] fi := 1 enddef;

def make_char =
 clearit; next_binary;
 for k=0 upto b: if a[k]=1:
  addto currentpicture also pix_picture shifted(0,-k*pix_ht); fi endfor
 charcode := charcode+1; chardp := b*charht;
 scantokens extra_endchar; shipout currentpicture enddef;

charwd := pix_wd#; charht := pix_ht#; chardx := pix_wd*mg;
b := -1;

if boolean large_pixels:
 for k=1 upto 7: make_char; charlist k:k+120; endfor
 charcode := 120; b := -1;
 addto pix_picture also pix_picture shifted (chardx,0);
 charwd := 2charwd; chardx := 2chardx;
 for k=1 upto 7: make_char; endfor
else: for k=1 upto 63: make_char; endfor
 let next_binary = next_special_binary;
 for k=64 upto 120: make_char; endfor
 for k=121,122: charcode := k;
  addto currentpicture also currentpicture shifted (chardx,0);
  charwd := 2charwd; chardx := 2chardx;
  scantokens extra_endchar; shipout currentpicture; endfor
 charlist 120:121:122; fi

font_coding_scheme "GFGRAY";
font_size 8(pix_wd#);
font_normal_space pix_wd#;
font_x_height pix_ht#;
font_quad pix_wd#;
fontdimen 8: if known rulethickness: rulethickness
 else: pix_wd#/(2rep) fi;
bye.