mdocml: Begin cleaning up scaling units.

[kristaps@mdocml.bsd.lv]

Log Message:
-----------
Begin cleaning up scaling units.
Start with the horizontal terminal specifiers, making sure that they match
up with troff.
Then move on to PS, PDF, and HTML, noting that we stick to the terminal 
default width for "u".
Lastly, fix some completely-wrong documentation and note that we diverge
from troff w/r/t "u".

Modified Files:
--------------
    mdocml:
        html.c
        roff.7
        term_ascii.c
        term_ps.c

Revision Data
-------------
Index: roff.7
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/roff.7,v
retrieving revision 1.55
retrieving revision 1.56
diff -Lroff.7 -Lroff.7 -u -p -r1.55 -r1.56
--- roff.7
+++ roff.7
@@ -239,8 +239,9 @@ 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
@@ -254,7 +255,7 @@ 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
@@ -262,7 +263,6 @@ 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.
@@ -1347,6 +1347,12 @@ The term
 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 ,
Index: term_ascii.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/term_ascii.c,v
retrieving revision 1.28
retrieving revision 1.29
diff -Lterm_ascii.c -Lterm_ascii.c -u -p -r1.28 -r1.29
--- term_ascii.c
+++ term_ascii.c
@@ -230,31 +230,41 @@ ascii_hspan(const struct termp *p, const
 	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;
 	}
 
Index: html.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/html.c,v
retrieving revision 1.161
retrieving revision 1.162
diff -Lhtml.c -Lhtml.c -u -p -r1.161 -r1.162
--- html.c
+++ html.c
@@ -760,6 +760,8 @@ bufcat_su(struct html *h, const char *p,
 	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]);
 }
Index: term_ps.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/term_ps.c,v
retrieving revision 1.63
retrieving revision 1.64
diff -Lterm_ps.c -Lterm_ps.c -u -p -r1.63 -r1.64
--- term_ps.c
+++ term_ps.c
@@ -1115,30 +1115,40 @@ ps_hspan(const struct termp *p, const st
 	 * 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);
+	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_PC:
-		r = PNT2AFM(p, su->scale * 12.0);
-		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;
--
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