Begin cleanup of scaling units.

Note that we use 240u := 1i for all devices, even -Tps and -Tpdf.
Big fix of -Tascii rendering of f, m, and u.
Small fix of -Tascii rendering of c.
Big fix of -Thtml rendering of u.
Big fix of -Tps rendering of m, p, and u.
Clarify -Tps rendering of c.
Correct documentation of scaling units, in particular with respect to u.
This for example improves rendering of the OpenGL manuals.
Joint work with kristaps@.

4 files changed, 60 insertions, 32 deletions

diff --git a/share/man/man7/roff.7 b/share/man/man7/roff.7
index ef2c03ae4bf..299d67fce7b 100644
--- a/share/man/man7/roff.7
+++ b/share/man/man7/roff.7
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: roff.7,v 1.34 2014/07/07 11:34:41 schwarze Exp $
+.\"	$OpenBSD: roff.7,v 1.35 2014/08/13 22:09:28 schwarze Exp $
 .\"
 .\" Copyright (c) 2010, 2011, 2012 Kristaps Dzonsons <kristaps@bsd.lv>
 .\" Copyright (c) 2010, 2011, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: July 7 2014 $
+.Dd $Mdocdate: August 13 2014 $
 .Dt ROFF 7
 .Os
 .Sh NAME
@@ -237,8 +237,9 @@ pica (~1/6 inch)
 .It p
 point (~1/72 inch)
 .It f
-synonym for
+scale
 .Sq u
+by 65536
 .It v
 default vertical span
 .It m
@@ -252,7 +253,7 @@ width of rendered
 .Pq en
 character
 .It u
-default horizontal span
+default horizontal span for the terminal
 .It M
 mini-em (~1/100 em)
 .El
@@ -260,7 +261,6 @@ mini-em (~1/100 em)
 Using anything other than
 .Sq m ,
 .Sq n ,
-.Sq u ,
 or
 .Sq v
 is necessarily non-portable across output media.
@@ -1346,6 +1346,12 @@ refers to groff version 1.15.
 .Pp
 .Bl -dash -compact
 .It
+The
+.Sq u
+scaling unit is the default terminal unit.
+In traditional troff systems, this unit would change depending on the
+output media.
+.It
 In mandoc, the
 .Sx \&EQ ,
 .Sx \&TE ,
diff --git a/usr.bin/mandoc/html.c b/usr.bin/mandoc/html.c
index 9cf447c7e4e..27a0a0949d1 100644
--- a/usr.bin/mandoc/html.c
+++ b/usr.bin/mandoc/html.c
@@ -1,4 +1,4 @@
-/*	$Id: html.c,v 1.39 2014/08/13 15:19:24 schwarze Exp $ */
+/*	$Id: html.c,v 1.40 2014/08/13 22:09:28 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2011, 2012, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -758,6 +758,8 @@ bufcat_su(struct html *h, const char *p, const struct roffsu *su)
 	v = su->scale;
 	if (SCALE_MM == su->unit && 0.0 == (v /= 100.0))
 		v = 1.0;
+	else if (SCALE_BU == su->unit)
+		v /= 24.0;
 
 	bufcat_fmt(h, "%s: %.2f%s;", p, v, roffscales[su->unit]);
 }
diff --git a/usr.bin/mandoc/term_ascii.c b/usr.bin/mandoc/term_ascii.c
index a1b02b525ff..2086699bca5 100644
--- a/usr.bin/mandoc/term_ascii.c
+++ b/usr.bin/mandoc/term_ascii.c
@@ -1,4 +1,4 @@
-/*	$Id: term_ascii.c,v 1.16 2014/08/08 16:00:23 schwarze Exp $ */
+/*	$Id: term_ascii.c,v 1.17 2014/08/13 22:09:28 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -209,32 +209,42 @@ ascii_hspan(const struct termp *p, const struct roffsu *su)
 	double		 r;
 
 	/*
-	 * Approximate based on character width.  These are generated
-	 * entirely by eyeballing the screen, but appear to be correct.
+	 * Approximate based on character width.
+	 * None of these will be actually correct given that an inch on
+	 * the screen depends on character size, terminal, etc., etc.
 	 */
-
 	switch (su->unit) {
+	case SCALE_BU:
+		r = su->scale * 10.0 / 240.0;
+		break;
 	case SCALE_CM:
-		r = su->scale * 4.0;
+		r = su->scale * 10.0 / 2.54;
+		break;
+	case SCALE_FS:
+		r = su->scale * 2730.666;
 		break;
 	case SCALE_IN:
 		r = su->scale * 10.0;
 		break;
+	case SCALE_MM:
+		r = su->scale / 100.0;
+		break;
 	case SCALE_PC:
-		r = (su->scale * 10.0) / 6.0;
+		r = su->scale * 10.0 / 6.0;
 		break;
 	case SCALE_PT:
-		r = (su->scale * 10.0) / 72.0;
-		break;
-	case SCALE_MM:
-		r = su->scale / 1000.0;
+		r = su->scale * 10.0 / 72.0;
 		break;
 	case SCALE_VS:
 		r = su->scale * 2.0 - 1.0;
 		break;
-	default:
+	case SCALE_EN:
+	case SCALE_EM:
 		r = su->scale;
 		break;
+	case SCALE_MAX:
+		abort();
+		break;
 	}
 
 	return(r);
diff --git a/usr.bin/mandoc/term_ps.c b/usr.bin/mandoc/term_ps.c
index 542a7c37853..5f0fdc31a5d 100644
--- a/usr.bin/mandoc/term_ps.c
+++ b/usr.bin/mandoc/term_ps.c
@@ -1,4 +1,4 @@
-/*	$Id: term_ps.c,v 1.27 2014/08/08 16:00:23 schwarze Exp $ */
+/*	$Id: term_ps.c,v 1.28 2014/08/13 22:09:28 schwarze Exp $ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -1110,31 +1110,41 @@ ps_hspan(const struct termp *p, const struct roffsu *su)
 	 * All of these measurements are derived by converting from the
 	 * native measurement to AFM units.
 	 */
-
 	switch (su->unit) {
-	case SCALE_CM:
-		r = PNT2AFM(p, su->scale * 28.34);
-		break;
-	case SCALE_IN:
-		r = PNT2AFM(p, su->scale * 72.0);
-		break;
-	case SCALE_PC:
-		r = PNT2AFM(p, su->scale * 12.0);
+	case SCALE_BU:
+		/*
+		 * Traditionally, the default unit is fixed to the
+		 * output media.  So this would refer to the point.  In
+		 * mandoc(1), however, we stick to the default terminal
+		 * scaling unit so that output is the same regardless
+		 * the media.
+		 */
+		r = PNT2AFM(p, su->scale * 72.0 / 240.0);
 		break;
-	case SCALE_PT:
-		r = PNT2AFM(p, su->scale * 100.0);
+	case SCALE_CM:
+		r = PNT2AFM(p, su->scale * 72.0 / 2.54);
 		break;
 	case SCALE_EM:
 		r = su->scale *
 		    fonts[(int)TERMFONT_NONE].gly[109 - 32].wx;
 		break;
-	case SCALE_MM:
-		r = PNT2AFM(p, su->scale * 2.834);
-		break;
 	case SCALE_EN:
 		r = su->scale *
 		    fonts[(int)TERMFONT_NONE].gly[110 - 32].wx;
 		break;
+	case SCALE_IN:
+		r = PNT2AFM(p, su->scale * 72.0);
+		break;
+	case SCALE_MM:
+		r = su->scale *
+		    fonts[(int)TERMFONT_NONE].gly[109 - 32].wx / 100.0;
+		break;
+	case SCALE_PC:
+		r = PNT2AFM(p, su->scale * 12.0);
+		break;
+	case SCALE_PT:
+		r = PNT2AFM(p, su->scale * 1.0);
+		break;
 	case SCALE_VS:
 		r = su->scale * p->ps->lineheight;
 		break;