> What's needed is a macro that can be called inline in arg
> 3 to start underlining, and another macro in arg 4 to stop
> underlining. Even if ul.tmac could be coerced into behaving
> this way (I've tussled with it, without success), it seems
> to me that the macros in ul.tmac are an awful lot of hoops
> to jump through for something as basic as underlining.
>
> Hence wondering about .cu.
If you're satisfied with a solution that works *only* with the
postscript device, then this can be achieved with device-control
escapes. Here's something to play around with. It redefines[*]
grops's basic text-printing functions to memorize the position
at the start of a piece of text and once the text is printed
draws a line to the remembered beginning position.
[*] You can also write the modified definitions directly into
the prologue file instead.
.\"
.\" ----------------------------------------------------------------
.de XX
ps: def
grops begin
/strikethrough
{ grops begin
/X { currentpoint currentfont /FontMatrix get 3 get 250 mul add
/y0 exch def /x0 exch def } def
/Y { currentpoint 0 currentfont /FontMatrix get 3 get dup
50 mul setlinewidth 250 mul rmoveto x0 y0 lineto stroke moveto } def
end }
def
/underline
{ grops begin
/X { currentpoint currentfont /FontMatrix get 3 get -60 mul add
/y0 exch def /x0 exch def } def
/Y { currentpoint 0 currentfont /FontMatrix get 3 get dup
50 mul setlinewidth -60 mul rmoveto x0 y0 lineto stroke moveto } def
end }
def
/normal
{ grops begin
/X { } def
/Y { } def
end }
def
normal
/A { X show Y } def
/B { 0 SC 3 -1 roll X widthshow Y } def
/C { 0 exch X ashow Y } def
/D { 0 exch 0 SC 5 2 roll X awidthshow Y } def
/E { 0 rmoveto X show Y } def
/F { 0 rmoveto 0 SC 3 -1 roll X widthshow Y } def
/G { 0 rmoveto 0 exch X ashow Y } def
/H { 0 rmoveto 0 exch 0 SC 5 2 roll X awidthshow Y } def
/I { 0 exch rmoveto X show Y } def
/J { 0 exch rmoveto 0 SC 3 -1 roll X widthshow Y } def
/K { 0 exch rmoveto 0 exch X ashow Y } def
/L { 0 exch rmoveto 0 exch 0 SC 5 2 roll X awidthshow Y } def
/M { rmoveto X show Y } def
/N { rmoveto 0 SC 3 -1 roll X widthshow Y } def
/O { rmoveto 0 exch X ashow Y } def
/P { rmoveto 0 exch 0 SC 5 2 roll X awidthshow Y } def
/Q { moveto X show Y } def
/R { moveto 0 SC 3 -1 roll X widthshow Y } def
/S { moveto 0 exch X ashow Y } def
/T { moveto 0 exch 0 SC 5 2 roll X awidthshow Y } def
end
..
.de underline
\X'ps: exec underline'\c
..
.de normal
\X'ps: exec normal'\c
..
.de strikethrough
\X'ps: exec strikethrough'\c
..
.\" ----------------------------------------------------------------
.sp 3c
.ll 4c
\Y[XX]\c
.strikethrough
The general syntax for writing groff documents is relatively easy,
but writing extensions to the roff language can be a bit harder.
.normal
The roff language is line-oriented.
.underline
There are only two kinds of lines,
control lines and text lines.
.normal
The control lines start with a control character,
by default a period \(lq.\(rq or a single quote \(lq'\(rq;
all other lines are text lines.
