218 lines
5.9 KiB
Groff
218 lines
5.9 KiB
Groff
'\" e
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.\" This man page must be preprocessed with eqn.
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.\"
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.\" $Id: groff_out.5,v 1.2 1993/08/02 17:44:22 mycroft Exp $
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.\"
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.ie \n(.g .ds ic \/
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.el .ds ic \^
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.TH GROFF_OUT 5 "6 August 1992" "Groff Version 1.08"
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.SH NAME
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groff_out \- groff intermediate output format
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.SH DESCRIPTION
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This manual page describes the format output by GNU troff.
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The output format used by GNU troff is very similar to that used
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by Unix device-independent troff. Only the differences are documented
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here.
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.LP
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The argument to the
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.B s
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command is in scaled points (units of
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.IR points/ n ,
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where
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.I n
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is the argument to the
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.B sizescale
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command in the DESC file.)
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The argument to the
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.B x\ Height
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command is also in scaled points.
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.LP
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The first three output commands are guaranteed to be:
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.IP
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.BI x\ T\ device
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.br
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.BI x\ res\ n\ h\ v
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.br
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.B x init
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.LP
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If the
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.B tcommand
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line is present in the DESC file, troff will use the following
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two commands
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.TP
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.BI t xxx
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.I xxx
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is any sequence of characters terminated by a space or a newline;
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the first character should be printed at the current position,
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the the current horizontal position should be increased by
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the width of the first character, and so on for each character.
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The width of the character is that given in the font file,
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appropriately scaled for the current point size, and rounded
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so that it is a multiple of the horizontal resolution.
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Special characters cannot be printed using this command.
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.TP
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.BI u n\ xxx
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This is same as the
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.B t
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command except that after printing each character, the current horizontal
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position is increased by the sum of the width of that character
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and
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.IR n .
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.LP
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Note that single characters can have the eighth bit set, as can the
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names of fonts and special characters.
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.LP
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The names of characters and fonts an be of arbitrary length; drivers
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should not assume that they will be only two characters long.
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.LP
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When a character is to be printed, that character will always be
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in the current font.
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Unlike device-independent troff, it is not necessary
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for drivers to search special fonts to find a character.
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.LP
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The
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.B D
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drawing command has been extended.
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These extensions will only be used by GNU pic if the
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.B \-x
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option is given.
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.TP
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\fBDf \fIn\fR\*(ic\en
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Set the shade of gray to be used for filling solid objects to
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.IR n ;
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.I n
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must be an integer between 0 and 1000, where 0 corresponds solid white
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and 1000 to solid black, and values in between correspond to
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intermediate shades of gray.
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This applies only to solid circles, solid ellipses and solid
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polygons.
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By default, a level of 1000 will be used.
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Whatever color a solid object has, it should completely obscure
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everything beneath it.
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A value greater than 1000 or less than 0 can also be used:
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this means fill with the shade of gray that is currently being used
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for lines and text.
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Normally this will be black, but some drivers may provide
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a way of changing this.
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.TP
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\fBDC \fId\fR\*(ic\en
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Draw a solid circle with a diameter of
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.I d
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with the leftmost point at the current position.
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.TP
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\fBDE \fIdx dy\fR\*(ic\en
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Draw a solid ellipse with a horizontal diameter of
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.I dx
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and a vertical diameter of
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.I dy
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with the leftmost point at the current position.
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.EQ
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delim $$
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.EN
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.TP
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\fBDp\fR $dx sub 1$ $dy sub 1$ $dx sub 2$ $dy sub 2$ $...$ $dx sub n$ $dy sub n$\en
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Draw a polygon with,
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for $i = 1 ,..., n+1$, the
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.IR i -th
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vertex at the current position
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$+ sum from j=1 to i-1 ( dx sub j , dy sub j )$.
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At the moment,
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GNU pic only uses this command to generate triangles and rectangles.
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.TP
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\fBDP\fR $dx sub 1$ $dy sub 1$ $dx sub 2$ $dy sub 2$ $...$ $dx sub n$ $dy sub n$\en
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Like
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.B Dp
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but draw a solid rather than outlined polygon.
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.TP
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\fBDt \fIn\fR\*(ic\en
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Set the current line thickness to
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.I n
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machine units.
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Traditionally Unix troff drivers use a line thickness proportional to the current
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point size; drivers should continue to do this if no
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.B Dt
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command has been given, or if a
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.B Dt
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command has been given with a negative value of
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.IR n .
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A zero value of
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.I n
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selects the smallest available line thickness.
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.LP
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A difficulty arises in how the current position should be changed after
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the execution of these commands.
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This is not of great importance since the code generated by GNU pic
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does not depend on this.
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Given a drawing command of the form
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.IP
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\fB\eD\(fm\fIc\fR $x sub 1$ $y sub 1$ $x sub 2$ $y sub 2$ $...$ $x sub n$ $y sub n$\(fm
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.LP
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where
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.I c
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is not one of
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.BR c ,
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.BR e ,
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.BR l ,
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.B a
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or
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.BR ~ ,
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Unix troff will treat each of the $x sub i$ as a horizontal quantity,
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and each of the $y sub i$ as a vertical quantity and will assume that
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the width of the drawn object is $sum from i=1 to n x sub i$,
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and that the height is $sum from i=1 to n y sub i$.
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(The assumption about the height can be seen by examining the
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.B st
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and
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.B sb
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registers after using such a
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.B D
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command in a \ew escape sequence.)
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This rule also holds for all the original drawing commands
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with the exception of
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.BR De .
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For the sake of compatibility GNU troff also follows this rule,
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even though it produces an ugly result in the case of the
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.BR Df ,
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.BR Dt ,
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and, to a lesser extent,
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.B DE
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commands.
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Thus after executing a
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.B D
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command of the form
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.IP
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\fBD\fIc\fR $x sub 1$ $y sub 1$ $x sub 2$ $y sub 2$ $...$ $x sub n$ $y sub n$\en
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.LP
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the current position should be increased by
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$( sum from i=1 to n x sub i , sum from i=1 to n y sub i )$.
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.LP
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There is a continuation convention which permits the argument to the
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.B x\ X
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command to contain newlines:
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when outputting the argument to the
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.B x\ X
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command, GNU troff
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will follow each newline in the argument with a
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.B +
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character
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(as usual, it will terminate the entire argument with a newline);
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thus if the line after the line containing the
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.B x\ X
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command starts with
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.BR + ,
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then the newline ending the line containing the
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.B x\ X
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command should be treated as part of the argument to the
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.B x\ X
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command,
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the
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.B +
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should be ignored,
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and the part of the line following the
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.B +
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should be treated like the part of the line following the
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.B x\ X
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command.
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.SH "SEE ALSO"
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.BR groff_font (5)
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