Improve overstriking. When overstriking a wider character with a

narrower one, center the latter horizontally.  After a group of
characters printed in the same position, advance by the width of
the widest one among them.

diff --git a/usr.bin/mandoc/term_ps.c b/usr.bin/mandoc/term_ps.c
index 08cefaf..4fc73db 100644 (file)
--- a/usr.bin/mandoc/term_ps.c
+++ b/usr.bin/mandoc/term_ps.c
@@ -1,7 +1,7 @@
-/*     $OpenBSD: term_ps.c,v 1.36 2014/12/19 17:10:42 schwarze Exp $ */
+/*     $OpenBSD: term_ps.c,v 1.37 2015/01/21 19:40:22 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -58,6 +58,7 @@ struct        termp_ps {
 #define        PS_NEWPAGE       (1 << 2)       /* new page, no words yet */
 #define        PS_BACKSP        (1 << 3)       /* last character was backspace */
        size_t            pscol;        /* visible column (AFM units) */
+       size_t            pscolnext;    /* used for overstrike */
        size_t            psrow;        /* visible row (AFM units) */
        char             *psmarg;       /* margin buf */
        size_t            psmargsz;     /* margin buf size */
@@ -1067,7 +1068,7 @@ ps_fclose(struct termp *p)
 static void
 ps_letter(struct termp *p, int arg)
 {
-       size_t          savecol;
+       size_t          savecol, wx;
        char            c;
 
        c = arg >= 128 || arg <= 0 ? '?' : arg;
@@ -1139,7 +1140,30 @@ ps_letter(struct termp *p, int arg)
                        ps_setfont(p, p->ps->nextf);
                }
                p->ps->nextf = TERMFONT_NONE;
+
+               /*
+                * For an overstrike, if a previous character
+                * was wider, advance to center the new one.
+                */
+
+               if (p->ps->pscolnext) {
+                       wx = fonts[p->ps->lastf].gly[(int)p->ps->last-32].wx;
+                       if (p->ps->pscol + wx < p->ps->pscolnext)
+                               p->ps->pscol = (p->ps->pscol +
+                                   p->ps->pscolnext - wx) / 2;
+               }
+
                ps_pletter(p, p->ps->last);
+
+               /*
+                * For an overstrike, if a previous character
+                * was wider, advance to the end of the old one.
+                */
+
+               if (p->ps->pscol < p->ps->pscolnext) {
+                       ps_pclose(p);
+                       p->ps->pscol = p->ps->pscolnext;
+               }
        }
 
        /*
@@ -1153,13 +1177,19 @@ ps_letter(struct termp *p, int arg)
 
        /*
         * For an overstrike, back up to the previous position.
+        * If the previous character is wider than any it overstrikes,
+        * remember the current position, because it might also be
+        * wider than all that will overstrike it.
         */
 
        if (savecol != SIZE_MAX) {
+               if (p->ps->pscolnext < p->ps->pscol)
+                       p->ps->pscolnext = p->ps->pscol;
                ps_pclose(p);
                p->ps->pscol = savecol;
                p->ps->flags &= ~PS_BACKSP;
-       }
+       } else
+               p->ps->pscolnext = 0;
 }
 
 static void