stable 2001.07.02

7 files changed, 1024 insertions, 378 deletions

diff --git a/metapost/context/metafun.mp b/metapost/context/metafun.mp
index e8fd1a762..cf63d289f 100644
--- a/metapost/context/metafun.mp
+++ b/metapost/context/metafun.mp
@@ -37,6 +37,7 @@ input mp-text.mp ;
 input mp-shap.mp ; 
 input mp-butt.mp ; 
 input mp-char.mp ; 
+input mp-step.mp ; 
 input mp-grph.mp ; 
 
 dump ; endinput .
diff --git a/metapost/context/mp-char.mp b/metapost/context/mp-char.mp
index 373200fc2..476199e23 100644
--- a/metapost/context/mp-char.mp
+++ b/metapost/context/mp-char.mp
@@ -1,3 +1,5 @@
+% to be cleaned up, namespace needed ! ! ! ! !
+
 %D \module
 %D   [       file=mp-char.mp,
 %D        version=1998.10.10,
@@ -17,55 +19,10 @@ if   known context_char : endinput         ; fi ;
 
 boolean context_char ; context_char := true ; 
 
-vardef enlarged_path (expr p, w) =              % NAAR mp-tool
-  (llcorner p shifted (-w,-w) --
-   lrcorner p shifted ( w,-w) --
-   urcorner p shifted ( w, w) --
-   ulcorner p shifted (-w, w) -- cycle)
-enddef;
-
-secondarydef p peepholed q = 
-  begingroup ; 
-  save start ; pair start ; start := point 0 of p ; 
- %drawdot start scaled_to_grid withpen pencircle scaled 2shape_line_width withcolor red ;
-  if xpart start >= xpart center p : 
-    if ypart start >= ypart center p : 
-      urcorner q -- ulcorner q -- llcorner q -- lrcorner q -- 
-      reverse  p -- lrcorner q -- cycle 
-    else :
-      lrcorner q -- urcorner q -- ulcorner q -- llcorner q -- 
-      reverse  p -- llcorner q -- cycle 
-    fi  
-  else :
-    if ypart start > ypart center p : 
-      ulcorner q -- llcorner q -- lrcorner q -- urcorner q -- 
-      reverse  p -- urcorner q -- cycle 
-    else :
-      llcorner q -- lrcorner q -- urcorner q -- ulcorner q --
-      reverse  p -- ulcorner q -- cycle 
-    fi  
-  fi 
-  endgroup 
-enddef ;
-
-boolean intersection_found ; 
-
-secondarydef p intersection_point q = 
-  begingroup 
-    save x_, y_ ; 
-    (x_,y_) = p intersectiontimes q ;
-    if x_<0 : 
-      intersection_found := false ;  
-      center p % origin
-    else : 
-      intersection_found := true ;  
-      .5[point x_ of p, point y_ of q] 
-    fi 
-  endgroup
-enddef ;
-
 current_position := 0 ;
 
+% kan naar elders 
+
 def save_text_position (expr p) =  % beware: clip shift needed
   current_position := current_position + 1 ;
   savedata
@@ -76,11 +33,8 @@ enddef ;
 
 %D settings
 
-grid_width   := 60pt ;
-grid_height  := 40pt ;
-
-shape_width  := 45pt ;
-shape_height := 30pt ;
+grid_width   := 60pt ; grid_height  := 40pt ;
+shape_width  := 45pt ; shape_height := 30pt ;
 
 chart_offset :=  2pt ;
 
@@ -131,7 +85,7 @@ def show_shapes (expr n) =
 
 enddef ; 
 
-%D connections
+%D connections -> namespace needed ! ! ! 
 
 color connection_line_color ;
 
@@ -895,7 +849,7 @@ def end_chart =
          (cmax_x,cmax_y)--(cmin_x,cmax_y)--cycle))
        scaled_to_grid ;
  %draw p withcolor red ; 
-  p := enlarged_path (p,chart_offset) ;
+  p := p enlarged chart_offset ;
   clip currentpicture to p ;
   setbounds currentpicture to p ;
   savedata
diff --git a/metapost/context/mp-core.mp b/metapost/context/mp-core.mp
index 3bc42ee74..1951a6bef 100644
--- a/metapost/context/mp-core.mp
+++ b/metapost/context/mp-core.mp
@@ -8,34 +8,32 @@
 %D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
 %C
 %C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. See licen-en.pdf for 
-%C details. 
+%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
+%C details.
 
-if unknown context_tool :    input mp-tool ; fi ; 
-if   known context_core : endinput         ; fi ; 
+if unknown context_tool :    input mp-tool ; fi ;
+if   known context_core : endinput         ; fi ;
 
-boolean context_core ; context_core := true ; 
+boolean context_core ; context_core := true ;
 
 pair lxy[], rxy[], cxy[], llxy[], lrxy[], ulxy[], urxy[] ;
-path pxy[] ; 
+path pxy[] ;
 numeric hxy[], wxy[], dxy[], nxy[] ;
 
 def box_found (expr n,x,y,w,h,d) =
   not ((x=0) and (y=0) and (w=0) and (h=0) and (d=0))
 enddef ;
 
-% left / right page problem ! ! ! ! !
-
 def initialize_box_pos (expr pos,n,x,y,w,h,d) =
   pair lxy, rxy, cxy, llxy, lrxy, ulxy, urxy ;
   path pxy ; numeric hxy, wxy, dxy, nxy;
   lxy  := (x,y)                         ; lxy[pos]  := lxy  ;
-  llxy := (x,y-d)                       ; llxy[pos] := llxy ; 
-  lrxy := (x+w,y-d)                     ; lrxy[pos] := lrxy ; 
-  urxy := (x+w,y+h)                     ; urxy[pos] := urxy ; 
+  llxy := (x,y-d)                       ; llxy[pos] := llxy ;
+  lrxy := (x+w,y-d)                     ; lrxy[pos] := lrxy ;
+  urxy := (x+w,y+h)                     ; urxy[pos] := urxy ;
   ulxy := (x,y+h)                       ; ulxy[pos] := ulxy ;
-  wxy  := w                             ; wxy[pos]  := wxy  ; 
-  hxy  := h                             ; hxy[pos]  := hxy  ; 
+  wxy  := w                             ; wxy[pos]  := wxy  ;
+  hxy  := h                             ; hxy[pos]  := hxy  ;
   dxy  := d                             ; dxy[pos]  := dxy  ;
   rxy  := lxy shifted (wxy,0)           ; rxy[pos]  := rxy  ;
   pxy  := llxy--lrxy--urxy--ulxy--cycle ; pxy[pos]  := pxy  ;
@@ -47,183 +45,340 @@ def initialize_box (expr n,x,y,w,h,d) =
 
   numeric bpos ; bpos := 0 ; initialize_box_pos(bpos,n,x,y,w,h,d) ;
 
-enddef ;   
-
-def initialize_area (expr fn,fx,fy,fw,fh,fd,
-                          tn,tx,ty,tw,th,td) =
-
-  numeric fpos ; fpos := 1 ; initialize_box_pos(fpos,fn,fx,fy,fw,fh,fd) ;
-  numeric tpos ; tpos := 2 ; initialize_box_pos(tpos,tn,tx,ty,tw,th,td) ;
-
-  do_initialize_area (fpos, tpos) ; 
-
 enddef ;
 
-def do_initialize_area (expr fpos, tpos) = 
+def do_initialize_area (expr fpos, tpos) =
   lxy  := lxy[fpos] ;
   llxy := (xpart llxy[fpos], ypart llxy[tpos]) ;
   lrxy := lrxy[tpos] ;
   urxy := (xpart urxy[tpos], ypart urxy[fpos]) ;
   ulxy := ulxy[fpos] ;
   wxy  := xpart lrxy - xpart llxy ;
-  hxy  := hxy[fpos] ; 
+  hxy  := hxy[fpos] ;
   dxy  := dxy[tpos] ;
   rxy  := lxy shifted (wxy,0) ;
   pxy  := llxy--lrxy--urxy--ulxy--cycle ;
   cxy  := center pxy ;
-enddef ; 
+enddef ;
 
-def initialize_par (expr fn,fx,fy,fw,fh,fd, ln,lx,ly,lw,lh,ld,
-                         rn,rx,ry,rw,rh,rd, tn,tx,ty,tw,th,td) =
+def initialize_par (expr fn,fx,fy,fw,fh,fd,
+                         tn,tx,ty,tw,th,td,
+                         mn,mx,my,mw,mh,md,
+                         pn,px,py,pw,ph,pd,
+                         rw,rl,rr,rh,ra,ri) =
 
   numeric fpos ; fpos := 1 ; initialize_box_pos(fpos,fn,fx,fy,fw,fh,fd) ;
-  numeric lpos ; lpos := 3 ; initialize_box_pos(lpos,ln,lx,ly,lw,lh,ld) ;
-  numeric rpos ; rpos := 4 ; initialize_box_pos(rpos,rn,rx,ry,rw,rh,rd) ;
   numeric tpos ; tpos := 2 ; initialize_box_pos(tpos,tn,tx,ty,tw,th,td) ;
+  numeric mpos ; mpos := 3 ; initialize_box_pos(mpos,mn,mx,my,mw,mh,md) ;
+  numeric ppos ; ppos := 4 ; initialize_box_pos(ppos,pn,px,py,pw,ph,pd) ;
 
-  do_initialize_area (fpos, tpos) ;
-  do_initialize_par  (fpos, lpos, rpos, tpos) ;
+  numeric par_strut_height, par_strut_depth, par_line_height ;
 
-enddef ; 
+  par_strut_height := ph ; 
+  par_strut_depth  := pd ;
+  par_line_height  := ph + pd ;
 
-def do_initialize_par (expr fpos, lpos, rpos, tpos) =
+  do_initialize_area (fpos, tpos) ;
+  do_initialize_par  (fpos, tpos, mpos, ppos, rw,rl,rr,rh,ra,ri) ;
 
-  pair leftxy, righxy ; path txy, mxy, bxy ; % top mid bot
+enddef ;
 
-  leftxy := if xpart ulxy[fpos] > xpart ulxy[lpos] : ulxy[fpos] else : ulxy[lpos]  fi ;
-  righxy := if xpart urxy[tpos] < xpart urxy[rpos] : urxy[tpos] else : urxy[rpos] fi ;
+def do_initialize_par (expr fpos, tpos, mpos, ppos, rw,rl,rr,rh,ra,ri) =
+
+  pair lref, rref, pref, lhref, rhref ; 
+
+  % clip the page area to the left and right skips
+
+  llxy[mpos] := llxy[mpos] shifted (+rl,0) ; 
+  lrxy[mpos] := lrxy[mpos] shifted (-rr,0) ; 
+  urxy[mpos] := urxy[mpos] shifted (-rr,0) ; 
+  ulxy[mpos] := ulxy[mpos] shifted (+rl,0) ; 
+
+  % fixate the leftskip, rightskip and hanging indentation
+  
+  lref := (xpart llxy[mpos],ypart ulxy[ppos]) ; lhref := lref shifted (rh,0) ; 
+  rref := (xpart lrxy[mpos],ypart urxy[ppos]) ; rhref := rref shifted (rh,0) ; 
+
+  pref := lxy[ppos] ;  
+
+  if nxy[tpos] > nxy[fpos] : 
+    if nxy[fpos] = nxy[mpos] : 
+      % first of multiple pages 
+      llxy[tpos] := llxy[mpos] ; 
+      lrxy[tpos] := lrxy[mpos] ; 
+      urxy[tpos] := lrxy[mpos] shifted (0,par_line_height) ; 
+      ulxy[tpos] := llxy[mpos] shifted (0,par_line_height) ; 
+      boxgriddirection := down ; 
+    elseif nxy[tpos] = nxy[mpos] : 
+      % last of multiple pages 
+      llxy[fpos] := ulxy[mpos] shifted (0,-par_line_height) ; 
+      lrxy[fpos] := urxy[mpos] shifted (0,-par_line_height) ; 
+      urxy[fpos] := urxy[mpos] ; 
+      ulxy[fpos] := ulxy[mpos] ; 
+      boxgriddirection := up ; 
+    else : 
+      % middle of multiple pages 
+      llxy[fpos] := ulxy[mpos] shifted (0,-par_line_height) ; 
+      lrxy[fpos] := urxy[mpos] shifted (0,-par_line_height) ; 
+      urxy[fpos] := urxy[mpos] ; 
+      ulxy[fpos] := ulxy[mpos] ; 
+      llxy[tpos] := llxy[mpos] ; 
+      lrxy[tpos] := lrxy[mpos] ; 
+      urxy[tpos] := lrxy[mpos] shifted (0,par_line_height) ; 
+      ulxy[tpos] := llxy[mpos] shifted (0,par_line_height) ; 
+      boxgriddirection := up ; 
+    fi ;
+  else : 
+    % just one page 
+    boxgriddirection := up ; 
+  fi ; 
 
-  pxy := origin ; 
+  path txy, bxy, pxy, mxy ; 
 
-  if (round(ypart llxy[fpos]) = round(ypart ulxy[tpos])) and
-     (round(xpart lrxy[tpos]) < round(xpart llxy[fpos])) :
+  txy := originpath ; % top 
+  bxy := originpath ; % bottom 
+  pxy := originpath ; % composed
 
-    txy := llxy[fpos] -- (xpart lrxy[rpos], ypart lrxy[fpos]) --
-           (xpart urxy[rpos], ypart urxy[fpos]) -- ulxy[fpos] -- cycle ;
-    mxy := origin ;
-    bxy := (xpart llxy[lpos], ypart llxy[tpos]) -- lrxy[tpos] --
-           urxy[tpos] -- (xpart ulxy[lpos], ypart ulxy[tpos]) -- cycle ;
+  boolean lefthang, righthang, somehang ; 
 
-  elseif ypart llxy[fpos] = ypart llxy[tpos] :
+  % we only hang on the first of a multiple page background 
 
-    txy := llxy[fpos] -- lrxy[tpos] -- urxy[tpos] -- ulxy[fpos] --cycle ;
-    mxy := origin ;
-    bxy := origin ;
+  if nxy[mpos] > nxy[fpos] : 
+    lefthang := righthang := somehang := false ; 
+  else : 
+    lefthang := (rh>0) ; righthang := (rh<0) ; somehang := false ; 
+  fi ; 
 
+  if lefthang :
+    mxy  := boundingbox (lref -- lref shifted (rh,ra*par_line_height)) ; 
+  elseif righthang : 
+    mxy  := boundingbox (rref -- rref shifted (rh,ra*par_line_height)) ; 
   else :
+    mxy  := originpath ;  
+  fi ;
 
-    txy := (xpart lrxy[rpos], ypart lrxy[fpos]) --
-           (xpart urxy[rpos], ypart urxy[fpos]) --
-           ulxy[fpos] -- llxy[fpos]  -- cycle ;
-    mxy := (xpart llxy[lpos], ypart ulxy[tpos]) --
-           (xpart llxy[rpos], ypart ulxy[tpos]) --
-           (xpart lrxy[rpos], ypart lrxy[fpos]) --
-           (xpart llxy[lpos], ypart llxy[fpos]) -- cycle ;
-    bxy := (xpart llxy[lpos], ypart llxy[tpos]) --
-           (xpart righxy, ypart lrxy[tpos]) --
-           (xpart righxy, ypart urxy[tpos]) --
-           (xpart llxy[lpos], ypart ulxy[tpos]) -- cycle ;
-
-    if (round(point 0 of bxy) = round(point 1 of bxy)) or
-       (round(point 0 of bxy) = round(point 2 of bxy)) :
-      bxy := origin ;
-    fi ;
+  if round(ypart llxy[fpos]) = round(ypart llxy[tpos]) : 
 
-    if (round(point 0 of mxy) = round(point 1 of mxy)) or
-       (round(point 0 of mxy) = round(point 2 of mxy)) :
-      mxy := origin ;
-    fi ;
+    % We have a one-liner. Watch how er use the bottom pos for
+    % determining the height.
+
+    llxy[fpos] := (xpart llxy[fpos], ypart llxy[tpos]) ; 
+    ulxy[fpos] := (xpart ulxy[fpos], ypart ulxy[tpos]) ; 
 
-    if (round(point 0 of txy) = round(point 1 of txy)) or
-       (round(point 0 of txy) = round(point 2 of txy)) :
-      txy := origin ;
+  else : 
+
+    % We have a multi-liner. For convenience we now correct the 
+    % begin and end points for indentation.  
+
+    if lefthang and (round(ypart llxy[tpos]) >= round(ypart lrcorner mxy)) : 
+      llxy[tpos] := (xpart lhref, ypart llxy[tpos]) ;
+      ulxy[tpos] := (xpart lhref, ypart ulxy[tpos]) ;
+    else :
+      llxy[tpos] := (xpart  lref, ypart llxy[tpos]) ;
+      ulxy[tpos] := (xpart  lref, ypart ulxy[tpos]) ;
     fi ;
 
-    if (round (length(mxy)) > 1) :
-      if (round (length(txy)) < 2) :
-        if (round (length(bxy)) < 2) :
-          pxy := mxy ;
-        else :
-          pxy := point 0 of bxy -- point 1 of bxy -- point 2 of bxy --
-                 point 1 of mxy -- point 2 of mxy -- point 3 of mxy --
-                 cycle ;
-        fi ;
-      else :
-        if (round (length(bxy)) < 2) :
-          pxy := point 1 of mxy --
-                 point 1 of txy -- point 2 of txy -- point 3 of txy --
-                 point 3 of mxy -- point 0 of mxy --
-                 cycle ;
-        else : 
-          pxy := point 1 of mxy --
-                 point 1 of txy -- point 2 of txy -- point 3 of txy --
-                 point 3 of mxy -- 
-                 point 0 of bxy -- point 1 of bxy -- point 2 of bxy --
-                 cycle ;
-        fi ; 
-      fi ;
+    if righthang and (round(ypart lrxy[fpos]) >= round(ypart llcorner mxy)) :
+      lrxy[fpos] := (xpart rhref, ypart lrxy[fpos]) ;
+      urxy[fpos] := (xpart rhref, ypart urxy[fpos]) ;
+    else :
+      lrxy[fpos] := (xpart  rref, ypart lrxy[fpos]) ;
+      urxy[fpos] := (xpart  rref, ypart urxy[fpos]) ;  
     fi ;
 
+  fi ; 
+
+  somehang := (ypart ulxy[fpos]>ypart llcorner mxy) and 
+              (ypart llxy[tpos]<ypart llcorner mxy) ;
+
+  if round(ypart llxy[fpos]) = round(ypart llxy[tpos]) : 
+
+    % A (short) one-liner goes into the top box. 
+
+    txy := llxy[fpos] -- lrxy[tpos] -- urxy[tpos] -- ulxy[fpos] -- cycle ;
+
+  elseif (round(ypart llxy[fpos]) = round(ypart ulxy[tpos])) and
+         (round(xpart lrxy[tpos]) < round(xpart llxy[fpos])) :
+
+    % We have a sentence that spans two lines but with only end 
+    % of line and begin of line segments. We need to take care of 
+    % indentation. 
+
+    txy := llxy[fpos] -- lrxy[fpos] -- urxy[fpos] -- ulxy[fpos] -- cycle ;
+    bxy := llxy[tpos] -- lrxy[tpos] -- urxy[tpos] -- ulxy[tpos] -- cycle ;
+
+  elseif (round(ypart llxy[fpos]) = round(ypart ulxy[tpos])) :
+
+    % We have a sentence that spans two lines but with overlap.
+
+    pxy := llxy[tpos] -- lrxy[tpos] -- urxy[tpos] -- lrxy[fpos] --
+           urxy[fpos] -- ulxy[fpos] -- llxy[fpos] -- ulxy[tpos] -- cycle ;
+
+  elseif lefthang and somehang : 
+
+    % We have a sentence that spans more than two lines with 
+    % left hanging indentation. 
+
+    pxy := llxy[tpos] -- lrxy[tpos] -- urxy[tpos] -- 
+           (xpart urxy[fpos],ypart urxy[tpos]) --
+           urxy[fpos] -- ulxy[fpos] -- llxy[fpos] -- 
+           if round(ypart urxy[tpos]) < round(ypart llcorner mxy) : 
+             (xpart lrcorner mxy,ypart llxy[fpos]) -- 
+             lrcorner mxy -- 
+             (xpart llxy[tpos],ypart llcorner mxy) -- 
+           else : 
+             (xpart llxy[tpos],ypart llxy[fpos]) -- 
+           fi 
+           cycle ;
+
+  elseif righthang and somehang :
+
+    % We have a sentence that spans more than two lines with 
+    % right hanging indentation. 
+
+    pxy := llxy[tpos] -- lrxy[tpos] -- urxy[tpos] -- 
+           if round(ypart urxy[tpos]) < round(ypart llcorner mxy) :  
+             (xpart lrcorner mxy,ypart urxy[tpos]) --
+             lrcorner mxy -- llcorner mxy --
+           else : 
+             (xpart urxy[fpos],ypart urxy[tpos]) --
+           fi 
+           urxy[fpos] -- ulxy[fpos] -- llxy[fpos] -- 
+           (xpart llxy[tpos],ypart llxy[fpos]) -- 
+           cycle ;
+
+  else :       
+
+    % We have a sentence that spans more than two lines with 
+    % no hanging indentation. 
+
+    pxy := llxy[tpos] -- lrxy[tpos] -- urxy[tpos] -- 
+           (xpart urxy[fpos],ypart urxy[tpos]) --
+           urxy[fpos] -- ulxy[fpos] -- llxy[fpos] -- 
+           (xpart llxy[tpos],ypart llxy[fpos]) -- cycle ;
+
   fi ;
 
+  pxy := simplified pxy ; 
+  pxy := unspiked   pxy ; 
+
 enddef ;
 
-color boxfillcolor ; boxfillcolor := .8white ;
-color boxlinecolor ; boxlinecolor := .8blue  ;
+color   boxgridcolor     ; boxgridcolor     := .8red ;
+color   boxlinecolor     ; boxlinecolor     := .8blue ;
+color   boxfillcolor     ; boxfillcolor     := .8white ;
+numeric boxgridtype      ; boxgridtype      := 0 ;
+numeric boxlinetype      ; boxlinetype      := 1 ;
+numeric boxfilltype      ; boxfilltype      := 1 ;
+pair    boxgriddirection ; boxgriddirection := up ;
+numeric boxgridwidth     ; boxgridwidth     := 1pt ;
+numeric boxlinewidth     ; boxlinewidth     := 1pt ;
+numeric boxlineradius    ; boxlineradius    := 0pt ; 
 
 def draw_box =
-  pickup pencircle scaled .5 ;
-  draw pxy withcolor boxlinecolor ;
-  draw lxy -- rxy withcolor boxlinecolor ;
-% pickup pencircle scaled 1.5 ;
-% draw llxy withcolor green ;
-% draw lrxy withcolor green ;
-% draw urxy withcolor green ;
-% draw ulxy withcolor green ;
-% draw cxy withcolor red ;
-% pickup pencircle scaled 1 ;
-% draw lxy withcolor red ;
-% draw rxy withcolor red ;
+  draw pxy withcolor boxlinecolor withpen pencircle scaled boxlinewidth ;
+  draw lxy -- rxy withcolor boxlinecolor withpen pencircle scaled boxgridwidth ;
 enddef ;
 
-def draw_par =
-  pickup pencircle scaled .5 ;
-  if length pxy > 1 :
-    fill pxy withcolor boxfillcolor ; draw pxy withcolor boxlinecolor ;
-  else :
-    draw_par_top ; draw_par_mid ; draw_par_bot ;
-  fi ;
-% pickup pencircle scaled 1.5 ;
-% draw llxy[lpos] withcolor red ;
-% draw llxy[rpos] withcolor red ;
-% draw llxy[tpos] withcolor green ;
-% draw llxy[fpos] withcolor green ;
+def draw_par  = % 1 2 11
+  numeric distance ; distance := .5cm ; 
+  do_draw_par(pxy) ; do_draw_par(txy) ; do_draw_par(bxy) ;
+  for i = pxy, txy, bxy :
+        if boxgridtype= 1 :
+      draw baseline_grid (i,boxgriddirection,true ) withcolor boxgridcolor ;
+    elseif boxgridtype= 2 :
+      draw baseline_grid (i,boxgriddirection,false) withcolor boxgridcolor ;
+    elseif boxgridtype=11 :
+      draw graphic_grid(i,distance,distance,distance/2,distance/2) ;
+    fi ;
+  endfor ;
 enddef ;
 
-def draw_par_top =
-  pickup pencircle scaled .5 ;
-  if length txy > 1 :
-    fill txy withcolor boxfillcolor ; draw txy withcolor boxlinecolor ;
-  fi ;
+def show_par  =
+  def do_show_par (expr p, r, c) =
+    if length(p) > 2 : for i=0 upto length(p) :
+      draw fullcircle scaled r shifted point i of p 
+        withpen pencircle scaled .5pt withcolor c ;
+    endfor ; fi ;
+  enddef ; 
+  if length(mxy) > 2 : 
+    draw mxy dashed evenly 
+      withpen pencircle scaled .5pt withcolor .5white ; 
+  fi ;   
+  do_show_par(txy, 4pt, .5green) ;
+  do_show_par(bxy, 6pt, .5blue ) ;
+  do_show_par(pxy, 8pt, .5red  ) ;
+  draw pref withpen pencircle scaled 2pt ; 
 enddef ;
 
-def draw_par_mid =
-  pickup pencircle scaled .5 ;
-  if length mxy > 1 :
-    fill mxy withcolor boxfillcolor ; draw mxy withcolor boxlinecolor ;
+vardef do_draw_par (expr p) =
+  if length p > 2 :
+    save pp ; path pp ; 
+    if (boxlineradius>0) and (boxlinetype=2) : 
+      pp := p cornered boxlineradius ; 
+    else : 
+      pp := p ; 
+    fi ; 
+    if boxfilltype>0 :
+      fill pp withcolor boxfillcolor ; 
+    fi ;
+    if boxlinetype>0 :
+      draw pp withcolor boxlinecolor withpen pencircle scaled boxlinewidth ; 
+    fi ; 
   fi ;
 enddef ;
 
-def draw_par_bot =
-  pickup pencircle scaled .5 ;
-  if length bxy > 1 :
-    fill bxy withcolor boxfillcolor ; draw bxy withcolor boxlinecolor ;
-  fi ;
+vardef baseline_grid (expr pxy, pdir, at_baseline) =
+  if (par_line_height>0) : % and (round(bbheight(pxy))>=round(par_line_height)) :
+    save grid, start ; picture grid ; pair start ;
+    grid := image
+      ( %fails with inlinespace
+        %
+        %if pdir=up :
+        %  for i = if at_baseline : par_strut_depth else : 0 fi
+        %          step par_line_height until bbheight(pxy) :
+        %    start := llcorner pxy shifted (0,+i) ;
+        %    draw start -- start shifted (bbwidth(pxy),0) 
+        %      withpen pencircle scaled boxgridwidth 
+        %      withcolor boxgridcolor ; 
+        %  endfor ;
+        %else :
+          for i = if at_baseline : par_strut_height else : 0 fi
+                  step par_line_height until bbheight(pxy) :
+            start := ulcorner pxy shifted (0,-i) ;
+            draw start -- start shifted (bbwidth(pxy),0) 
+              withpen pencircle scaled boxgridwidth 
+              withcolor boxgridcolor ; 
+          endfor ;
+        %fi ; 
+      ) ;
+    clip grid to pxy ;
+    grid
+  else :
+    nullpicture
+  fi
+enddef ;
+
+vardef graphic_grid (expr pxy, dx, dy, x, y) =
+  if (bbheight(pxy)>dy) and (bbwidth(pxy)>dx) :
+    save grid ; picture grid ;
+    grid := image
+      ( for i = xpart llcorner pxy step dx until xpart lrcorner pxy :
+          draw (i,ypart llcorner pxy) -- (i,ypart ulcorner pxy) 
+            withpen pencircle scaled boxgridwidth ; 
+        endfor ;
+        for i = ypart llcorner pxy step dy until ypart ulcorner pxy :
+          draw (xpart llcorner pxy,i) -- (xpart lrcorner pxy,i) 
+            withpen pencircle scaled boxgridwidth ; 
+        endfor ) ;
+    clip grid shifted (x,y) to pxy ;
+    grid
+  else :
+    nullpicture
+  fi
 enddef ;
 
 def anchor_box (expr n,x,y,w,h,d) =
-% bboxmargin := 0 ;
-% setbounds currentpicture to unitsquare shifted (x,y) ;
   currentpicture := currentpicture shifted (-x,-y) ;
 enddef ;
 
@@ -231,4 +386,4 @@ let draw_area   = draw_box ;
 let anchor_area = anchor_box ;
 let anchor_par  = anchor_box ;
 
-endinput ; 
+endinput ;
diff --git a/metapost/context/mp-shap.mp b/metapost/context/mp-shap.mp
index 5b95e71aa..f8bfd50cf 100644
--- a/metapost/context/mp-shap.mp
+++ b/metapost/context/mp-shap.mp
@@ -258,4 +258,50 @@ def some_shape ( expr shape_type      ,
  
 enddef ; 
 
+vardef drawshape (expr t, p, lw, lc, fc) =
+  save pp ; 
+  if t>1 : % normal shape
+    path pp ;
+    pp := some_shape_path(t) xyscaled(bbwidth(p), bbheight(p)) shifted center p ;
+    fill pp withcolor fc ;
+    draw pp withpen pencircle scaled lw withcolor lc ;
+  elseif t=1 : % background only 
+    path pp ; 
+    pp := fullsquare xyscaled(bbwidth(p), bbheight(p)) shifted center p ;
+    fill pp withcolor fc ;
+  else : % dimensions only 
+    picture pp ; pp := nullpicture ; 
+    setbounds pp to fullsquare xyscaled(bbwidth(p), bbheight(p)) shifted center p ;
+    draw pp ; 
+  fi ; 
+enddef ;
+
+vardef drawline (expr t, p, lw, lc) =
+  if (t>0) and (length(p)>1) :
+    saveoptions ;
+    drawoptions(withpen pencircle scaled lw withcolor lc) ;
+    draw p ;
+    if     t =  1 : 
+      draw arrowheadonpath(p,1) ;
+    elseif t =  2 :
+      draw arrowheadonpath(reverse p,1) ;
+    elseif t =  3 :
+      for $ = p,reverse p : draw arrowheadonpath($,1) ; endfor ; 
+    elseif t = 11 :
+      draw arrowheadonpath(p,1/2) ;
+    elseif t = 12 :
+      draw arrowheadonpath(reverse p,1/2) ;
+    elseif t = 13 :
+      for $=p,reverse p : draw arrowheadonpath($,1) ; endfor ;
+      for $=p,reverse p : draw arrowheadonpath($,3/4) ; endfor ;
+    elseif t = 21 :
+      for $=1/5,1/2,4/5 : draw arrowheadonpath(p,$) ; endfor ;
+    elseif t = 22 :
+      for $=1/5,1/2,4/5 : draw arrowheadonpath(reverse p,$) ; endfor ;
+    elseif t = 23 :
+      for $=p,reverse p : draw arrowheadonpath($,1/4) ; endfor ;
+    fi ;
+  fi ; 
+enddef ;
+
 endinput ;  
diff --git a/metapost/context/mp-spec.mp b/metapost/context/mp-spec.mp
index db7cbd256..918e73fb4 100644
--- a/metapost/context/mp-spec.mp
+++ b/metapost/context/mp-spec.mp
@@ -2,238 +2,244 @@
 %D   [       file=mp-spec.mp,
 %D        version=1999.6.26,
 %D          title=\CONTEXT\ \METAPOST\ graphics,
-%D       subtitle=special extensions, 
+%D       subtitle=special extensions,
 %D         author=Hans Hagen,
 %D           date=\currentdate,
 %D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
 %C
 %C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. See licen-en.pdf for 
-%C details. 
+%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
+%C details.
 
-%D This module is rather preliminary and subjected to 
-%D changes. Here we closely cooperates with the \METAPOST\ 
-%D to \PDF\ converter module built in \CONTEXT\ and provides 
-%D for instance shading. More information can be found in 
-%D type {supp-mpe.tex}. 
+% (r,g,b) => cmyk: g=1, b=hash
+%         => rest: g=n, b=whatever 
 
-if unknown context_tool :    input mp-tool ; fi ; 
-if   known context_spec : endinput         ; fi ; 
+%D This module is rather preliminary and subjected to
+%D changes. Here we closely cooperates with the \METAPOST\
+%D to \PDF\ converter module built in \CONTEXT\ and provides
+%D for instance shading. More information can be found in
+%D type {supp-mpe.tex}.
 
-boolean context_spec ; context_spec := true ; 
+if unknown context_tool :    input mp-tool ; fi ;
+if   known context_spec : endinput         ; fi ;
+
+boolean context_spec ; context_spec := true ;
 
 numeric _special_counter_ ; _special_counter_ :=   0 ;
-numeric _color_counter_   ; _color_counter_   :=   0 ; 
-numeric _special_signal_  ; _special_signal_  := 123 ; 
+numeric _color_counter_   ; _color_counter_   :=   0 ;
+numeric _special_signal_  ; _special_signal_  := 123 ;
 
 %D When set to \type {true}, shading will be supported. Some
-%D day I will also write an additional directive. 
+%D day I will also write an additional directive.
 
-boolean _inline_specials_ ; _inline_specials_ := false ; 
+boolean _inline_specials_ ; _inline_specials_ := false ;
 
 %D Because we want to output only those specials that are
 %D actually used in a figure, we need a bit complicated
 %D bookkeeping and collection of specials. At the cost of some
-%D obscurity, we now have rather efficient resources. 
+%D obscurity, we now have rather efficient resources.
 
-string _all_specials_ ; _all_specials_ := "" ; 
+string _all_specials_ ; _all_specials_ := "" ;
 
-vardef add_special_signal = 
-  if (length _all_specials_>0) :
-    special ("%%MetaPostSpecials: 1.0 " & decimal _special_signal_ ) ; % version
-  fi ; 
-enddef ; 
+vardef add_special_signal =
+  if (length _all_specials_>0) : % write the version number
+    special ("%%MetaPostSpecials: 1.0 " & decimal _special_signal_ ) ;
+  fi ;
+enddef ;
 
-vardef add_extra_specials = 
-  scantokens _all_specials_ ; 
-enddef ; 
+vardef add_extra_specials =
+  scantokens _all_specials_ ;
+enddef ;
 
-vardef reset_extra_specials = 
+vardef reset_extra_specials =
   _all_specials_ := "" ;
-enddef ; 
-
-extra_endfig := 
-  " add_special_signal ; "   &  
-    extra_endfig             & 
-  " add_extra_specials ; "   &  
-  " reset_extra_specials ; " ; 
-
-def flush_special (expr typ, siz, dat) = 
-  _special_counter_ := _special_counter_ + 1 ; 
-  if _inline_specials_ : 
-    _all_specials_ := _all_specials_ 
+enddef ;
+
+extra_endfig :=
+  " add_special_signal ; "   &
+    extra_endfig             &
+  " add_extra_specials ; "   &
+  " reset_extra_specials ; " ;
+
+def flush_special (expr typ, siz, dat) =
+  _special_counter_ := _special_counter_ + 1 ;
+  if _inline_specials_ :
+    _all_specials_ := _all_specials_
       & "special "
       & "(" & ditto
-      & dat & " " 
-      & decimal _special_counter_ & " " 
-      & decimal typ & " " 
-      & decimal siz 
-      & " special" 
+      & dat & " "
+      & decimal _special_counter_ & " "
+      & decimal typ & " "
+      & decimal siz
+      & " special"
       & ditto & ");" ;
   else :
-   _all_specials_ := _all_specials_ 
-      & "special " 
+   _all_specials_ := _all_specials_
+      & "special "
       & "(" & ditto
-      & "%%MetaPostSpecial: "  
-      & decimal siz & " " 
-      & dat & " " 
-      & decimal _special_counter_ & " "  
-      & decimal typ 
+      & "%%MetaPostSpecial: "
+      & decimal siz & " "
+      & dat & " "
+      & decimal _special_counter_ & " "
+      & decimal typ
       & ditto & ");" ;
-  fi ; 
-enddef ; 
+  fi ;
+enddef ;
 
-%D Shade allocation. 
+%D Shade allocation.
 
-vardef define_circular_shade (expr a, b, ra, rb, ca, cb) = 
-  flush_special(3, 17, "0 1 1" & 
-    dddecimal ca & ddecimal a & " " & decimal ra &  
+vardef define_circular_shade (expr a, b, ra, rb, ca, cb) =
+  flush_special(3, 17, "0 1 1" &
+    dddecimal ca & ddecimal a & " " & decimal ra &
     dddecimal cb & ddecimal b & " " & decimal rb ) ;
-  _special_counter_ 
-enddef ;  
+  _special_counter_
+enddef ;
 
-vardef define_linear_shade (expr a, b, ca, cb) = 
-  flush_special(2, 15, "0 1 1" & 
-    dddecimal ca & ddecimal a & 
-    dddecimal cb & ddecimal b ) ; 
-  _special_counter_ 
-enddef ;  
+vardef define_linear_shade (expr a, b, ca, cb) =
+  flush_special(2, 15, "0 1 1" &
+    dddecimal ca & ddecimal a &
+    dddecimal cb & ddecimal b ) ;
+  _special_counter_
+enddef ;
 
 %D A few predefined shading macros.
 
-boolean trace_shades ; trace_shades := false ; 
+boolean trace_shades ; trace_shades := false ;
 
-def linear_shade (expr p, n, ca, cb) = 
-  begingroup ; 
+def linear_shade (expr p, n, ca, cb) =
+  begingroup ;
   save a, b, sh ; pair a, b ;
-  if     (n=1) : a := llcorner p ; b := urcorner p ; 
-  elseif (n=2) : a := llcorner p ; b := ulcorner p ; 
-  elseif (n=3) : a := lrcorner p ; b := ulcorner p ; 
-  else         : a := llcorner p ; b := lrcorner p ; 
+  if     (n=1) : a := llcorner p ; b := urcorner p ;
+  elseif (n=2) : a := llcorner p ; b := ulcorner p ;
+  elseif (n=3) : a := lrcorner p ; b := ulcorner p ;
+  else         : a := llcorner p ; b := lrcorner p ;
+  fi ;
+  fill p withshade define_linear_shade (a,b,ca,cb) ;
+  if trace_shades :
+    drawarrow a -- b withpen pencircle scaled 1pt ;
+  fi ;
+  endgroup ;
+enddef ;
+
+def circular_shade (expr p, n, ca, cb) =
+  begingroup ;
+  save ab, r ; pair ab ; numeric r ;
+  r := (xpart lrcorner p - xpart llcorner p) ++
+       (ypart urcorner p - ypart lrcorner p) ;
+  if     (n=1) : ab := llcorner p ;
+  elseif (n=2) : ab := lrcorner p ;
+  elseif (n=3) : ab := urcorner p ;
+  elseif (n=4) : ab := ulcorner p ;
+  else         : ab := center p ; r := .5r ;
   fi ;
-  fill p withshade define_linear_shade (a,b,ca,cb) ; 
-  if trace_shades : 
-    drawarrow a -- b withpen pencircle scaled 1pt ; 
-  fi ; 
-  endgroup ; 
-enddef ;  
-
-def circular_shade (expr p, n, ca, cb) = 
-  begingroup ; 
-  save ab, r ; pair ab ; numeric r ; 
-  r := (xpart lrcorner p - xpart llcorner p) ++ 
-       (ypart urcorner p - ypart lrcorner p) ; 
-  if     (n=1) : ab := llcorner p ; 
-  elseif (n=2) : ab := lrcorner p ; 
-  elseif (n=3) : ab := urcorner p ; 
-  elseif (n=4) : ab := ulcorner p ; 
-  else         : ab := center p ; r := .5r ; 
-  fi ; 
   fill p withshade define_circular_shade(ab,ab,0,r,ca,cb) ;
-  if trace_shades : 
-    drawarrow ab -- ab shifted (0,r) withpen pencircle scaled 1pt ; 
-  fi ; 
-  endgroup ; 
-enddef ;  
+  if trace_shades :
+    drawarrow ab -- ab shifted (0,r) withpen pencircle scaled 1pt ;
+  fi ;
+  endgroup ;
+enddef ;
 
-%D Since a \type {fill p withshade s} syntax looks better 
-%D than some macro, we implement a new primary.  
+%D Since a \type {fill p withshade s} syntax looks better
+%D than some macro, we implement a new primary.
 
-primarydef p withshade sc = 
+primarydef p withshade sc =
   hide (_color_counter_ := _color_counter_ + 1)
-  p withcolor (_special_signal_/1000,_color_counter_/1000,sc/1000) 
-enddef ; 
+  p withcolor (_special_signal_/1000,_color_counter_/1000,sc/1000)
+enddef ;
 
-%D Figure inclusion. 
+%D Figure inclusion.
 
-numeric cef ; cef := 0 ; 
+numeric cef ; cef := 0 ;
 
-def externalfigure primary filename = 
-  doexternalfigure (filename) 
-enddef ; 
+def externalfigure primary filename =
+  doexternalfigure (filename)
+enddef ;
 
-def doexternalfigure (expr filename) text transformation = 
-  begingroup ; save p, t ; picture p ; transform t ; 
-  p := nullpicture ; t := identity transformation ; 
+def doexternalfigure (expr filename) text transformation =
+  begingroup ; save p, t ; picture p ; transform t ;
+  p := nullpicture ; t := identity transformation ;
   flush_special(10, 9,
-    dddecimal (xxpart t, yxpart t, xypart t) & " " & 
-    dddecimal (yypart t,  xpart t,  ypart t) & " " & filename) ; 
+    dddecimal (xxpart t, yxpart t, xypart t) & " " &
+    dddecimal (yypart t,  xpart t,  ypart t) & " " & filename) ;
   addto p contour unitsquare scaled 0 ;
-  setbounds p to unitsquare transformed t ;   
-  _color_counter_ := _color_counter_ + 1 ; cef := cef + 1 ; 
-  draw p withcolor (_special_signal_/1000,_color_counter_/1000,cef/1000) ;
-  endgroup ; 
-enddef ; 
+  setbounds p to unitsquare transformed t ;
+%  _color_counter_ := _color_counter_ + 1 ; cef := cef + 1 ;
+%  draw p withcolor (_special_signal_/1000,_color_counter_/1000,cef/1000) ;
+draw p withcolor (_special_signal_/1000,cef/1000,_special_counter_/1000) ;
+  endgroup ;
+enddef ;
 
-%D Experimental: 
+%D Experimental:
 
-numeric currenthyperlink ; currenthyperlink := 0 ; 
+numeric currenthyperlink ; currenthyperlink := 0 ;
 
 def hyperlink primary t = dohyperlink(t) enddef ;
 def hyperpath primary t = dohyperpath(t) enddef ;
 
-def dohyperlink (expr destination) text transformation  = 
-  begingroup ; save somepath ; path somepath ; 
-  somepath := fullsquare transformation ; 
+def dohyperlink (expr destination) text transformation  =
+  begingroup ; save somepath ; path somepath ;
+  somepath := fullsquare transformation ;
   dohyperpath(destination) somepath ;
-  endgroup ; 
-enddef ; 
+  endgroup ;
+enddef ;
 
-def dohyperpath (expr destination) expr somepath = 
-  begingroup ; 
+def dohyperpath (expr destination) expr somepath =
+  begingroup ;
   flush_special(20, 7,
-    ddecimal (xpart llcorner somepath, ypart llcorner somepath) & " " & 
-    ddecimal (xpart urcorner somepath, ypart urcorner somepath) & " " & destination) ; 
-  _color_counter_ := _color_counter_ + 1 ; 
-  currenthyperlink := currenthyperlink + 1 ; 
-  fill boundingbox unitsquare scaled 0 
-    withcolor 
-    (_special_signal_/1000,_color_counter_/1000,currenthyperlink/1000) ;
-  endgroup ; 
-enddef ; 
+    ddecimal (xpart llcorner somepath, ypart llcorner somepath) & " " &
+    ddecimal (xpart urcorner somepath, ypart urcorner somepath) & " " & destination) ;
+  currenthyperlink := currenthyperlink + 1 ;
+%  _color_counter_ := _color_counter_ + 1 ;
+  fill boundingbox unitsquare scaled 0 withcolor
+%    (_special_signal_/1000,_color_counter_/1000,currenthyperlink/1000) ;
+    (_special_signal_/1000,currenthyperlink/1000,_special_counter_/1000) ;
+  endgroup ;
+enddef ;
 
 % \setupinteraction[state=start]
 % \setupcolors     [state=start]
-% 
-% Hello There! \blank 
-% 
-% \startMPcode 
-% pickup pencircle scaled 5 ; 
-% draw fullcircle scaled 4cm withcolor red ;  
-% hyperpath "nextpage" boundingbox currentpicture ; 
+%
+% Hello There! \blank
+%
+% \startMPcode
+% pickup pencircle scaled 5 ;
+% draw fullcircle scaled 4cm withcolor red ;
+% hyperpath "nextpage" boundingbox currentpicture ;
 % draw origin withcolor blue ;
 % \stopMPcode
-% 
-% \blank Does it work or not? 
-% 
-% \startMPcode 
-% pickup pencircle scaled 5 ; 
-% draw fullcircle scaled 4cm withcolor red ;  
-% hyperpath "nextpage" fullcircle scaled 4cm ; 
+%
+% \blank Does it work or not?
+%
+% \startMPcode
+% pickup pencircle scaled 5 ;
+% draw fullcircle scaled 4cm withcolor red ;
+% hyperpath "nextpage" fullcircle scaled 4cm ;
 % draw origin withcolor blue ;
-% draw fullcircle scaled 4cm shifted (1cm,1cm);  
+% draw fullcircle scaled 4cm shifted (1cm,1cm);
 % \stopMPcode
-% 
-% \blank Does it work or not? \page Hello There! \blank 
-% 
-% \startMPcode 
-% pickup pencircle scaled 5 ; 
-% draw fullcircle scaled 2cm shifted (-2cm,-1cm) ;  
-% draw fullcircle scaled 3cm shifted (2cm,1cm) withcolor red ;  
-% draw fullcircle scaled 1cm ;  
-% hyperlink "previouspage" scaled 3cm shifted (2cm,1cm) ; 
-% draw origin withcolor blue ; 
+%
+% \blank Does it work or not? \page Hello There! \blank
+%
+% \startMPcode
+% pickup pencircle scaled 5 ;
+% draw fullcircle scaled 2cm shifted (-2cm,-1cm) ;
+% draw fullcircle scaled 3cm shifted (2cm,1cm) withcolor red ;
+% draw fullcircle scaled 1cm ;
+% hyperlink "previouspage" scaled 3cm shifted (2cm,1cm) ;
+% draw origin withcolor blue ;
 % \stopMPcode
-% 
-% \blank Does it work or not?  
+%
+% \blank Does it work or not?
 
 _cmyk_counter_ := 0 ;
 
-numeric cmykcolorhash[][][][] ;
+extra_endfig := " resetcmykcolors ; " & extra_endfig ;
 
-boolean cmykcolors ; % cmykcolors := true ;
+def resetcmykcolors =
+  numeric cmykcolorhash[][][][] ;
+enddef ;
 
-let normalcmyk = cmyk ; % see mp-tool.mp 
+resetcmykcolors ; boolean cmykcolors ; cmykcolors := false ; % true
 
 vardef cmyk(expr c,m,y,k) =
   if cmykcolors :
@@ -241,7 +247,7 @@ vardef cmyk(expr c,m,y,k) =
       _cmyk_counter_ := _cmyk_counter_ + 1 ;
       cmykcolorhash[c][m][y][k] := _cmyk_counter_ ;
       flush_special(1, 7,
-        decimal _cmyk_counter_ & " "  & 
+        decimal _cmyk_counter_ & " "  &
         decimal c & " " &
         decimal m & " " &
         decimal y & " " &
@@ -249,19 +255,19 @@ vardef cmyk(expr c,m,y,k) =
     fi
     (_special_signal_/1000,1/1000,cmykcolorhash[c][m][y][k]/1000)
   else :
-    normalcmyk(1-c-k,1-m-k,1-y-k)
+    (1-c-k,1-m-k,1-y-k)
   fi
 enddef ;
 
-%D Basic position tracking: 
+%D Basic position tracking:
 
-def register (expr label, width, height, offset) = 
-  begingroup ; 
+def register (expr label, width, height, offset) =
+  begingroup ;
   flush_special(50, 7,
-    ddecimal offset & " " & 
-    decimal  width  & " " & 
-    decimal  height & " " & label) ; 
-  endgroup ; 
-enddef ; 
+    ddecimal offset & " " &
+    decimal  width  & " " &
+    decimal  height & " " & label) ;
+  endgroup ;
+enddef ;
 
-endinput ; 
+endinput ;
diff --git a/metapost/context/mp-step.mp b/metapost/context/mp-step.mp
new file mode 100644
index 000000000..d602f7014
--- /dev/null
+++ b/metapost/context/mp-step.mp
@@ -0,0 +1,320 @@
+%D \module
+%D   [       file=mp-step.mp,
+%D        version=2001.05.22,
+%D          title=\CONTEXT\ \METAPOST\ graphics,
+%D       subtitle=steps,
+%D         author=Hans Hagen,
+%D           date=\currentdate,
+%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
+%C
+%C This module is part of the \CONTEXT\ macro||package and is
+%C therefore copyrighted by \PRAGMA. See licen-en.pdf for
+%C details.
+
+if unknown context_tool :    input mp-tool ; fi ;
+if   known context_step : endinput         ; fi ;
+
+boolean context_step ; context_step := true ;
+
+%D In the associated \TEX\ module \type {m-steps}, we describe
+%D three methods. The first method uses a different kind of
+%D code than the other two. The method we decided to use,
+%D is based on positional information (paths) provided by
+%D \CONTEXT.
+
+def initialize_step_variables =
+  save line_method, line_h_offset, line_v_offset ;
+  numeric line_method   ; line_method   := 1 ;
+  numeric line_h_offset ; line_h_offset := 3pt ;
+  numeric line_v_offset ; line_v_offset := 3pt ;
+enddef ;
+
+def begin_step_chart =
+  initialize_step_variables ;
+  save steps, texts, t, b, tb, nofcells ;
+  picture cells[][], texts[][][], lines[][][] ;
+  numeric t, b ; t := 1 ; b := 2 ;
+  numeric nofcells ; nofcells := 0 ;
+enddef ;
+
+def analyze_step_chart =
+  numeric n[], l[][], r[][] ; pair p[] ;
+  n[t] := n[b] := 0 ; numeric tb ; 
+  for i=1 upto nofcells : for nn = t, b :
+    if bbwidth(cells[nn][i])>0 : n[nn] := n[nn] + 1 ; fi ;
+    l[t][i] := r[t][i] := l[b][i] := r[b][i] := 0 ;
+  endfor ; endfor ;
+  % count left and right points
+  for i=1 upto nofcells-1 : for j=i upto nofcells-1 : for nn = t, b :
+    if bbwidth(texts[nn][i][j])>0 :
+      l[nn][i] := l[nn][i] + 1 ;
+      r[nn][j+1] := r[nn][j+1] + 1 ;
+    fi ;
+  endfor ; endfor ; endfor ;
+  % calculate left and right points
+  vardef do (expr nn, mm, ii, ss) =
+    if (l[nn][ii] + r[nn][ii]) > 1 : ss else : .5 fi
+      [ ulcorner cells[mm][ii], urcorner cells[mm][ii] ]
+  enddef ;
+  % combined rows
+  tb := if n[t]>0 : t else : b fi ;
+enddef ;
+
+vardef get_step_chart_top_line (expr i, j) =
+  if bbwidth(cells[tb][i])>0 :
+    if bbwidth(texts[t][i][j])>0 :
+      if bbwidth(cells[tb][j+1])>0 :
+        p[1] := top do(t, tb,   i, .6) ;
+        p[3] := top do(t, tb, j+1, .4) ;
+        p[2] := .5[p[1],p[3]] ;
+        if line_method = 1 :
+          p[2] := p[2] shifted (0, ypart
+            (llcorner texts[t][i][j] - ulcorner cells[tb][j+1])) ;
+        elseif line_method = 2 :
+          p[2] := center texts[t][i][j] ;
+        else :
+          % nothing
+        fi ;
+        p[1] := p[1] shifted (0,+line_v_offset) ;
+        p[2] := p[2] shifted (0,-line_v_offset) ;
+        p[3] := p[3] shifted (0,+line_v_offset) ;
+        (p[1] {up} ... p[2] ... {down} p[3])
+      else :
+        origin 
+      fi 
+    else :
+      origin 
+    fi 
+  else :
+    origin 
+  fi 
+enddef ; 
+
+vardef get_step_chart_bot_line (expr i, j) =
+  if bbwidth(cells[b][i])>0 :
+    if bbwidth(texts[b][i][j])>0 :
+      if bbwidth(cells[b][j+1])>0 :
+        p[1] := (bot do(b, b,   i, .6)) shifted (0,-bbheight(cells[b][i])) ;
+        p[3] := (bot do(b, b, j+1, .4)) shifted (0,-bbheight(cells[b][j+1])) ;
+        p[2] := .5[p[1],p[3]] ;
+        if line_method = 1 :
+          p[2] := p[2] shifted (0, -ypart
+            (llcorner cells[b][j+1] - ulcorner texts[b][i][j])) ;
+        elseif line_method = 2 :
+          p[2] := center texts[b][i][j] ;
+        fi ;
+        p[1] := p[1] shifted (0,-line_v_offset) ;
+        p[2] := p[2] shifted (0,+line_v_offset) ;
+        p[3] := p[3] shifted (0,-line_v_offset) ;
+        (p[1] {down} ... p[2] ... {up} p[3])
+      else :
+        origin 
+      fi 
+    else :
+      origin 
+    fi 
+  else :
+    origin 
+  fi 
+enddef ;
+
+def end_step_chart =
+  for i=1 upto nofcells :                         for nn = t, b : 
+      if bbwidth(cells[nn][i])   >0 : draw cells[nn][i]    ; fi ; 
+  endfor ;          endfor ;
+  for i=1 upto nofcells : for j=i upto nofcells : for nn = t, b : 
+    if known lines[nn][i][j] :
+      if bbwidth(lines[nn][i][j])>0 : draw lines[nn][i][j] ; fi ;
+    fi ; 
+  endfor ; endfor ; endfor ;
+  for i=1 upto nofcells : for j=i upto nofcells : for nn = t, b :
+      if bbwidth(texts[nn][i][j])>0 : draw texts[nn][i][j] ; fi ;
+  endfor ; endfor ; endfor ;
+enddef ;
+
+%D Step tables. 
+
+def begin_step_table =
+  initialize_step_variables ;
+  picture cells[], texts[], lines[] ;
+  numeric nofcells ; nofcells := 0 ;
+enddef ;
+
+def end_step_table =
+  for i=1 upto nofcells : if known cells[i] : if bbwidth(cells[i])>0 : 
+    draw cells[i] ; 
+  fi ; fi ; endfor ;
+  for i=1 upto nofcells : if known lines[i] : if bbwidth(lines[i])>0 : 
+    draw lines[i] ; 
+  fi ; fi ; endfor ;
+  for i=1 upto nofcells : if known texts[i] : if bbwidth(texts[i])>0 : 
+    draw texts[i] ;
+  fi ; fi ; endfor ;
+enddef ;
+
+vardef get_step_table_line (expr i) =
+  pair prev, self, next ;
+  if known texts[i] :
+    self := lft .5[llcorner texts[i], ulcorner texts[i] ] ;
+    prev := rt if known texts[i-1] : .3 else : .5 fi [lrcorner cells[i]  , urcorner cells[i]  ] ;
+    next := rt if known texts[i+1] : .7 else : .5 fi [lrcorner cells[i+1], urcorner cells[i+1]] ;
+    self := self shifted (-line_h_offset,0) ;
+    prev := prev shifted (+line_h_offset,0) ;
+    next := next shifted (+line_h_offset,0) ;
+    prev {right} ... self ... {left} next
+  else :
+    origin
+  fi
+enddef ;
+
+endinput
+
+%D The older method let \METAPOST\ do the typesetting. The
+%D macros needed for that are included here for educational
+%D purposes.
+%D
+%D \starttypen
+%D def initialize_step_variables =
+%D   save line_color, line_width, arrow_alternative,
+%D     text_fill_color, text_line_color, text_line_width, text_offset,
+%D     cell_fill_color, cell_line_color, cell_line_width, cell_offset,
+%D     line_h_offset, line_v_offset ;
+%D   color   line_color       ; line_color       := .4white ;
+%D   numeric line_width       ; line_width       := 1.5pt ;
+%D   color   text_fill_color  ; text_fill_color  := white ;
+%D   color   text_line_color  ; text_line_color  := red ;
+%D   numeric text_line_width  ; text_line_width  := 1pt ;
+%D   numeric text_offset      ; text_offset      := 2pt ;
+%D   color   cell_fill_color  ; cell_fill_color  := white ;
+%D   color   cell_line_color  ; cell_line_color  := blue ;
+%D   numeric cell_line_width  ; cell_line_width  := 1pt ;
+%D   numeric cell_offset      ; cell_offset      := 2pt ;
+%D   numeric line_alternative ; line_alternative := 1 ;
+%D   numeric line_h_offset    ; line_h_offset    := 3pt ;
+%D   numeric line_v_offset    ; line_v_offset    := 3pt ;
+%D enddef ;
+%D
+%D def begin_step_chart =
+%D   begingroup ;
+%D   initialize_step_variables ;
+%D   save steps, texts, t, b ;
+%D   picture cells[][]   ; numeric nofcells ; nofcells := 0 ;
+%D   picture texts[][][] ; numeric noftexts ; noftexts := 0 ;
+%D   numeric t, b ; t := 1 ; b := 2 ;
+%D enddef ;
+%D \stoptypen
+%D
+%D We use a couple of macros to store the content. In the
+%D second (third) alternative we will directly fill the
+%D cells.
+%D
+%D \starttypen
+%D def set_step_chart_cells (expr one, two) =
+%D   nofcells := nofcells + 1 ; noftexts := 0 ;
+%D   cells[t][nofcells] := textext.rt(one) ;
+%D   cells[b][nofcells] := textext.rt(two) ;
+%D enddef ;
+%D
+%D def set_step_chart_texts (expr one, two) =
+%D   noftexts := noftexts + 1 ;
+%D   texts[t][nofcells][noftexts] := textext.rt(one) ;
+%D   texts[b][nofcells][noftexts] := textext.rt(two) ;
+%D enddef ;
+%D \stoptypen
+%D
+%D If you compare the building macro with the later
+%D alternative, you will notice that here we explicitly
+%D have to calculate the distances and positions.
+%D
+%D \starttypen
+%D def end_step_chart =
+%D   numeric dx ; dx :=  0 ; path p ;
+%D   numeric n[] ; n[t] := n[b] := 0 ;
+%D   numeric stepsvdistance[] ;
+%D   vardef bbwidth  (expr p) = (xpart (lrcorner p - llcorner p)) enddef ;
+%D   vardef bbheight (expr p) = (ypart (urcorner p - lrcorner p)) enddef ;
+%D   stepsvdistance[t] := stepsvdistance[b] := 0 ;
+%D   for i=1 upto nofcells :
+%D     % find largest bbox
+%D     p := boundingbox steps
+%D       [if bbwidth(cells[t][i])>bbwidth(cells[b][i]): t else: b fi][i] ;
+%D     % assign largest bbox
+%D     for nn = t, b :
+%D       if bbwidth(cells[nn][i])>0 :
+%D         setbounds cells[nn][i] to p enlarged cell_offset ;
+%D         n[nn] := n[nn] + 1 ;
+%D       fi ;
+%D     endfor ;
+%D     % determine height
+%D     if n[t]>0 :
+%D       stepsvdistance[t] := bbheight(cells[t][1]) + intertextdistance ;
+%D     fi ;
+%D     % add to row
+%D     for nn = t, b :
+%D       cells[nn][i] := cells[nn][i] shifted (dx,stepsvdistance[nn]) ;
+%D       if bbwidth(cells[nn][i])>0 :
+%D         dowithpath (boundingbox cells[nn][i],
+%D           cell_line_width, cell_line_color, cell_background_color) ;
+%D       fi ;
+%D     endfor ;
+%D     % calculate position
+%D     dx := dx + interstepdistance + bbwidth(cells[b][i]) ;
+%D   endfor ;
+%D   boolean stacked ; stacked := false ;
+%D   numeric l[][], r[][], l[][], r[][] ;
+%D   pair pa, pb, pc ; path p[] ;
+%D   for i=1 upto nofcells :
+%D     l[t][i] := r[t][i] := l[b][i] := r[b][i] := 0 ;
+%D   endfor ;
+%D   % count left and right points
+%D   for i=1 upto nofcells : for j=1 upto nofcells : for nn = t, b :
+%D     if known texts[nn][i][j] : if bbwidth(texts[nn][i][j])>0 :
+%D       l[nn][i]   := l[nn][i]   + 1 ;
+%D         r[nn][j+i] := r[nn][j+i] + 1 ;
+%D         stacked := (stacked or (j>1)) ;
+%D         setbounds texts[nn][i][j] to boundingbox texts[nn][i][j] enlarged cell_offset ;
+%D     fi fi ;
+%D     endfor ; endfor ; endfor ;
+%D     % calculate left and right points
+%D     vardef do (expr nn, mm, ii, ss) =
+%D       if (l[nn][ii] > 0) and (r[nn][ii] > 0) : ss else : .5 fi
+%D         [ ulcorner cells[mm][ii],urcorner cells[mm][ii] ]
+%D     enddef ;
+%D     % draw arrow from left to right point
+%D     def dodo (expr nn, ii, jj, dd) =
+%D       drawarrow p[nn]
+%D         withpen pencircle scaled arrow_line_width
+%D         withcolor arrow_line_color ;
+%D       transform tr ; tr := identity
+%D         shifted point .5 along p[nn]
+%D         shifted -center texts[nn][ii][jj]
+%D         if not stacked : shifted (0,dd) fi ;
+%D         dowithpath ((boundingbox texts[nn][ii][jj]) transformed tr,
+%D           text_line_width, text_line_color, text_fill_color) ;
+%D     enddef ;
+%D     % draw top and bottom text boxes
+%D     for i=1 upto nofcells : for j=1 upto nofcells :
+%D       pickup pencircle scaled arrow_line_width ;
+%D       if known texts[t][i][j] : if bbwidth(texts[t][i][j]) > 0 :
+%D         pa := top do(t, if n[t]>0 : t else : b fi,   i, .6) ;
+%D         pb := top do(t, if n[t]>0 : t else : b fi, j+i, .4) ;
+%D         pc := .5[pa,pb] shifted (0,+step_arrow_depth) ;
+%D         p[t] := pa {up} .. if not stacked : pc .. fi {down} pb ;
+%D         dodo(t, i, j, +intertextdistance) ;
+%D       fi fi ;
+%D       if known texts[b][i][j] : if bbwidth(texts[b][i][j]) > 0 :
+%D         pa := (bot do(b, b,   i, .6)) shifted (0,-bbheight(cells[b][i])) ;
+%D         pb := (bot do(b, b, j+i, .4)) shifted (0,-bbheight(cells[b][j+i])) ;
+%D         pc := .5[pa,pb] shifted (0,-step_arrow_depth) ;
+%D         p[b] := pa {down} .. if not stacked : pc .. fi {up} pb ;
+%D         dodo(b, i, j, -intertextdistance) ;
+%D       fi fi ;
+%D     endfor ; endfor ;
+%D   endgroup ;
+%D enddef ;
+%D \stoptypen
+%D
+%D If you compare both methods, you will notice that the
+%D first method is the cleanest, but not the most efficient
+%D (since it needs \TEX\ runs within \METAPOST\ runs within
+%D \TEX\ runs).
diff --git a/metapost/context/mp-tool.mp b/metapost/context/mp-tool.mp
index 76c7708cf..408d56dfb 100644
--- a/metapost/context/mp-tool.mp
+++ b/metapost/context/mp-tool.mp
@@ -11,6 +11,8 @@
 %C therefore copyrighted by \PRAGMA. See mreadme.pdf for
 %C details.
 
+% a cleanup is needed, like using image and alike
+
 %D This module is rather preliminary and subjected to
 %D changes.
 
@@ -23,7 +25,28 @@ boolean context_tool ; context_tool := true ;
 prologues    := 2 ; % 1 = troff, 2 = tex
 warningcheck := 0 ;
 
-%D A semicolor to be used in specials:
+%D Namespace handling:
+
+% let exclamationmark = ! ; 
+% let questionmark    = ? ; 
+% 
+% def unprotect = 
+%   let ! = relax ; 
+%   let ? = relax ; 
+% enddef ;
+% 
+% def protect = 
+%   let ! = exclamationmark ;
+%   let ? = questionmark ; 
+% enddef ; 
+% 
+% unprotect ; 
+% 
+% mp!some!module = 10 ; show mp!some!module ; show somemodule ; 
+% 
+% protect ;
+
+%D A semicolor to be used in specials: ? ? ? 
 
 string semicolor ; semicolor := char 59 ;
 
@@ -31,7 +54,8 @@ string semicolor ; semicolor := char 59 ;
 %D high resolution boundingbox to the \POSTSCRIPT\ file. This
 %D hack is due to John Hobby himself.
 
-% somehow the first one gets no HiRes.
+% When somehow the first one gets no HiRes, then make sure 
+% that the format matches the mem sizes in the config file. 
 
 vardef ddecimal primary p =
   " " & decimal xpart p &
@@ -352,21 +376,21 @@ enddef;
 % TODO TODO TODO TODO, not yet ok 
 
 primarydef p xsized w =
-  (p scaled (w/(xpart urcorner p - xpart llcorner p)))  
+  (p if bbwidth(p)>0 : scaled (w/bbwidth(p)) fi) 
 enddef ;
 
 primarydef p ysized h =
-  (p scaled (h/(ypart urcorner p - ypart llcorner p)))  
+  (p if bbheight(p)>0 : scaled (h/bbheight(p)) fi) 
 enddef ;
 
-primarydef p sized wh =
-  (p xscaled (xpart wh/(xpart urcorner p - xpart llcorner p))  
-     yscaled (ypart wh/(ypart urcorner p - ypart llcorner p)))  
+primarydef p xysized wh =
+  (p if (bbwidth(p)>0) and (bbheight(p)>0) : 
+       xscaled (xpart wh/bbwidth(p)) yscaled (ypart wh/bbheight(p))
+     fi) 
 enddef ;
 
-primarydef p xysized wh =
-  (p xscaled (xpart wh/(xpart urcorner p - xpart llcorner p))  
-     yscaled (ypart wh/(ypart urcorner p - ypart llcorner p)))  
+primarydef p sized wh =
+  (p xysized wh) 
 enddef ;
 
 def xscale_currentpicture(expr w) =
@@ -617,6 +641,26 @@ primarydef p ulmoved d =
   ((ulcorner p) shifted (-xpart paired(d),+ypart paired(d)))
 enddef ;
 
+primarydef p leftenlarged d = 
+  (llcorner p shifted (-d,0) -- lrcorner p -- 
+   urcorner p -- ulcorner p shifted (-d,0) -- cycle)
+enddef ; 
+
+primarydef p rightenlarged d = 
+  (llcorner p -- lrcorner p shifted (d,0) -- 
+   urcorner p shifted (d,0) -- ulcorner p -- cycle) 
+enddef ; 
+
+primarydef p topenlarged d = 
+  (llcorner p -- lrcorner p -- 
+   urcorner p shifted (0,-d) -- ulcorner p shifted (0,-d) -- cycle) 
+enddef ; 
+
+primarydef p bottomenlarged d = 
+  (llcorner p shifted (0,d) -- lrcorner p shifted (0,d) -- 
+   urcorner p -- ulcorner p -- cycle) 
+enddef ; 
+
 %D Nice too:
 
 primarydef p superellipsed s =
@@ -705,6 +749,12 @@ enddef ;
 vardef  leftpath expr p = leftrightpath(p,true ) enddef ; 
 vardef rightpath expr p = leftrightpath(p,false) enddef ; 
 
+%D Drawoptions 
+
+def saveoptions =
+  save _op_ ; def _op_ = enddef ; 
+enddef ; 
+ 
 %D Tracing. 
 
 let normaldraw = draw ;
@@ -739,6 +789,16 @@ vardef drawarrowpath expr p =
   drawarrow p _pth_opt_ 
 enddef ; 
 
+def midarrowhead expr p =
+  arrowhead p cutafter 
+    (point length(p cutafter point .5 along p)+ahlength on p) 
+enddef ; 
+
+vardef arrowheadonpath (expr p, s) =
+  save autoarrows ; boolean autoarrows ; autoarrows := true ;
+  arrowhead p if s<1 : cutafter (point (s*arclength(p)+.5ahlength) on p) fi
+enddef ;
+ 
 %D Points.
 
 def drawpoint expr c = 
@@ -1126,8 +1186,6 @@ vardef anglebetween (expr a, b, str) = % path path string
   curve
 enddef ;
 
-
-
 % Stack
 
 picture currentpicturestack[] ; 
@@ -1337,7 +1395,11 @@ inner end ;
 
 % real fun
 
-color color_map[][][] ;
+def resetcolormap = 
+  color color_map[][][] ;
+enddef ; 
+
+resetcolormap ; 
 
 %color_map_resolution := 1000 ;
 %
@@ -1463,6 +1525,108 @@ vardef cmyk(expr c,m,y,k) =
   (1-c-k,1-m-k,1-y-k)
 enddef ;
 
+% handy 
+
+vardef bbwidth  (expr p) = 
+  (if known p : xpart (lrcorner p - llcorner p) else : 0 fi)
+enddef ; 
+
+vardef bbheight (expr p) = 
+  (if known p : ypart (urcorner p - lrcorner p) else : 0 fi)
+enddef ; 
+
+color nocolor ; numeric noline ; % both unknown signals 
+
+def dowithpath (expr p, lw, lc, bc) =
+  if known p : 
+    if known bc : 
+      fill p withcolor bc ;
+    fi ; 
+    if known lw and known lc : 
+      draw p withpen pencircle scaled lw withcolor lc ;
+    elseif known lw : 
+      draw p withpen pencircle scaled lw ;
+    elseif known lc : 
+      draw p withcolor lc ;
+    fi ; 
+  fi ; 
+enddef ;
+
+% result from metafont discussion list (denisr/boguslawj)
+
+def ]]  = ] ] enddef ; def ]]] = ] ] ] enddef ;
+def [[  = [ [ enddef ; def [[[ = [ [ [ enddef ;
+
+% not prefect, but useful since it removes redundant points.
+
+vardef dostraightened(expr sign, p) = 
+  if length(p)>1 : 
+    save pp ; path pp ; 
+    pp := point 0 of p ;
+    for i=1 upto length(p)-1 : 
+      if round(point i of p) <> round(point length(pp) of pp) : 
+        pp := pp -- point i of p ;
+      fi ; 
+    endfor ;
+    save n ; numeric n ; 
+    n := length(pp) ; 
+    for i=0 upto n : % evt hier ook round 
+     if unitvector(point i                        of pp  - 
+                   point if i=0 : n else : i-1 fi of pp) <> 
+ sign * unitvector(point if i=n : 0 else : i+1 fi of pp  - 
+                   point i                        of pp) : 
+        point i of pp --
+     fi 
+%
+% to test: 
+%
+%     if round(unitvector(point i                        of pp)) <> 
+% sign * round(unitvector(point if i=n : 0 else : i+1 fi of pp)) : 
+%        point i of pp --
+%     fi 
+%
+    endfor   
+    cycle 
+  else : 
+    p 
+  fi 
+enddef ; 
+
+% simplified : remove same points as well as redundant points 
+% unspiked   : remove same points as well as areas with zero distance 
+
+vardef simplified expr p = dostraightened(+1,p) enddef ;  
+vardef unspiked   expr p = dostraightened(-1,p) enddef ;  
+
+% path p ; 
+% p := (2cm,1cm) -- (2cm,1cm) -- (2cm,1cm) -- (3cm,1cm) -- 
+%      (4cm,1cm) -- (4cm,2cm) -- (4cm,2.5cm) -- (4cm,3cm) -- 
+%      (3cm,3cm) -- (2cm,3cm) -- (1cm,3cm) -- (-1cm,3cm) -- 
+%      .5[(-1cm,3cm),(1cm,1cm)] -- (1cm,1cm) -- cycle ; 
+% 
+% p := unitcircle scaled 4cm ; 
+% 
+% drawpath p ; drawpoints p ; drawpointlabels p ; 
+% p := p shifted (4cm,0) ; p := straightened p ; 
+% drawpath p ; drawpoints p ; drawpointlabels p ; 
+% p := p shifted (4cm,0) ; p := straightened p ; 
+% drawpath p ; drawpoints p ; drawpointlabels p ; 
+
+% new 
+
+path originpath ; originpath := origin -- cycle ;
+
+vardef unitvector primary z = 
+  if abs z = abs origin : z else : z/abs z fi  
+enddef;
+
+% also new 
+
+vardef anchored@#(expr p, z) =  
+  p shifted (z + (labxf@#*lrcorner p + labyf@#*ulcorner p
+       + (1-labxf@#-labyf@#)*llcorner p))
+enddef ;
+
 % done 
 
 endinput ;