Coloured text
Introduction
Mom’s support for coloured text is straightforward. You begin
by telling mom about the colours you want with
NEWCOLOR
or
XCOLOR.
Afterward, any time you want text to be coloured, you either colour
it with an
inline escape
that contains the colour name (e.g. \*[red]
or \*[blue]) or invoke the macro
COLOR
with the name of the colour you want.
For example, say you want to have the name “Jack” in the
sentence “All work and no play makes Jack a dull boy”
appear in yellow. You'd begin by telling mom about the colour,
yellow. There are two ways of doing this; see
NEWCOLOR
and
XCOLOR
for a full explanation of the difference between the two.
If you use XCOLOR, you'd enter this:
.XCOLOR yellow
If you use NEWCOLOR, you might enter:
.NEWCOLOR yellow RGB #FFFF00
After “defining” (or “initializing”) the
colour “yellow”, you'd colourize the name, Jack, either
with an inline escape
All work and no play makes \*[yellow]Jack\*[black] a dull boy.
or with the
COLOR
macro
All work and no play makes
.COLOR yellow
Jack
.COLOR black
a dull boy.
Notice, in both examples, that a) you have to set the colour back
to black after “Jack”, and b) you don’t have to
define or intialize the colour, black. Mom predefines it for you.
For information on using colour during
document processing,
see
Colour support in document processing.
Note:
Mom’s colour support is for text only. She doesn’t
support “fill” (or “background”) colour for
solid, enclosed graphical objects (polygons, ellipses) drawn with
groff’s \D
inline escapes,
although you may give a colour as one of the arguments to
mom’s “box” and “circle” macros,
DBX
and
DCL
when the first argument to these macros is SOLID.
Experts:
If you’re accustomed to using groff’s
.defcolor to define colours, and groff’s inline
\m[<colorname>] to call them, you may continue to
do so without confusing mom.
Creating (initializing) a colour with NEWCOLOR
Macro: NEWCOLOR <colour name> [<colour scheme>] <colour components>
NEWCOLOR lets you create a colour, rather like an artist mixing
paint on a palette. The colour isn’t used immediately;
NEWCOLOR merely tells mom how to mix the colour when you need it.
If you haven’t invoked .NEWCOLOR (or
.XCOLOR),
mom doesn’t have a clue what you mean when you reference a
colour (with
COLOR
or
\*[<color name>]).
The first argument to NEWCOLOR is a name for your colour. It
can be anything you like—provided it’s just one word
long—and can be caps, lower case, or any combination of the
two.
The second argument, which is entirely optional, is the
“colour scheme” you want mom to use when mixing the
colour. Valid arguments are
RBG (3 components: red green blue)
CYM (3 components: cyan yellow magenta)
CMYK (4 components: cyan magenta yellow black)
GRAY (1 component)
If you omit the second argument, mom assumes you
want RGB.
The final argument is the components of your colour. This can be
hexadecimal string starting with a pound sign (#) (for
colour values in the 0-255 range) or two pound signs (##)
(for colour values in the 0-65535 range), or it can be a series of
decimal digits, separated by spaces, one digit per component, with
the argument enclosed in double quotes. (If this is all gibberish
to you, see
Tips for newbies.)
Thus, to tell mom about a colour named “YELLOW”, you
could enter one of the following:
.NEWCOLOR YELLOW #FFFF00 \"or ##FFFFFFFF0000 or "1 1 0"
.NEWCOLOR YELLOW RGB #FFFF00 \"or ##FFFFFFFF0000 or "1 1 0"
.NEWCOLOR YELLOW CYM #00FF00 \"or ##0000FFFF0000 or "0 1 0"
.NEWCOLOR YELLOW CYMK #00FF0000 \"or ##0000FFFF00000000 or "0 0 1 0"
After you've told mom about a colour, you can then get her to set
text in that colour either with the
inline escape,
\*[<colorname>],
or the macro
COLOR.
(See the
example,
above.)
Note:
The colorname you give to NEWCOLOR may be used with groff’s
\m[<colorname>] inline escape (the \m
escape is used to set text and rule colours). Thus, assuming
a colorname “blueblack” set with NEWCOLOR,
\*[blueblack] and \m[blueblack] are
equivalent. Furthermore, the colorname can be given as an argument
to groff’s
primitive
request, .gcolor (which does the same thing as
\m[<colorname>]).
Equally, the colorname may be used with
\M[<colorname>] and .fcolor, which set
the “fill” colour for solid graphical objects.
Tips for newbies:
Colour manipulation can be tremendously confusing if you don’t
have a background in graphic arts or computing. My advice, if color
intimidates you, is to stick to using mom’s default RGB colour
scheme, and to fire up a color chooser that gives you the RGB values
you want for the colour you select. Plug those values into the
components argument to NEWCOLOR, and you’ll get the colour
you want. Both the KDE and gnome desktops have colour selectors
that provide you with the shorter RGB hexadecimal string. If
you’re not running KDE or gnome, the X utility, xcolorsel,
provides you with a similar functionality, although it only provides
RGB values for 256 pre-defined colours. If you use xcolorsel, be
sure to click the button “Display format” and select
“8 bit truncated rgb”.
Alternatively, you can use mom’s simpler
XCOLOR
macro to initialize one of the 256 pre-defined X colours by
supplying the name of the color as an argument.
Initializing a colour with XCOLOR
Macro: XCOLOR <X colorname> [<alias>]
<X colorname> must be all one word, all lower case.
(See
Finding X color names
for how to get a list of valid colour names.)
XCOLOR is similar to NEWCOLOR in that it tells mom to initialize a
colour, but it’s easier to use. All you have to do is pass
it, as an argument, the valid name of one of the 256 pre-defined
X colours. The name must be all one word, and, breaking with mom
policy, it must be entered in lower case.
For example, if you want to intialize the X colour, coral, all you
have to do is enter
.XCOLOR coral
Afterwards
.COLOR coral
will colourize subsequent text coral until you instruct mom to
return to black, or some other pre-defined, initialized colour.
(The
inline escape
\*[coral] will equally colourize text coral after you've
initialized the colour with XCOLOR.)
The downside of XCOLOR is that you can’t create custom
colours. This restriction, however, is mitigated by the fact that
for many users, 256 colours is more than enough to play around with.
While some X colours have fanciful names (peachpuff, papayawhip,
thistle, snow), many are self-explanatory and self-descriptive
in ordinary colour terms. “blue” is pure (rgb)
blue, “green” is pure (rgb) green, and so on.
Furthermore, for many X colors, there exist four variants, each
representing increasingly darker shades of the same colour.
For example, “blue1” is a relatively bright blue;
“blue2”, “blue3” and “blue4” are
increasingly darker shades. For that reason, you may find XCOLOR is
a better choice than NEWCOLOR when it comes to initializing common
colors.
The whimsical nature of X colour names sometimes makes for names
that are long to type in, e.g. “mediumspringgreen”. The
optional second argument to XCOLOR allows you to come up with more
convenient name by which to reference the colour. For example, you
could enter
.XCOLOR mediumspringgreen mygreen
or
.XCOLOR mediumspringgreen MYGREEN
so that whenever you want text mediumspringgreen-ed, you
can use either .COLOR mygreen (or
.COLOR MYGREEN) or the inline escape
\*[mygreen] (or \*[MYGREEN].)
Finding X color names
There are two ways of finding the names of the pre-defined X
colours. One is to consult the file, rgb.txt, included with all
X11 installations. The location of the file on a Debian GNU/Linux
distribution is typically /etc/X11/rgb.txt. Other distributions and
other X installations may have the file in another location. The
file lists the colour names, but doesn’t show you what the
colours actually look like.
A better way to get the colour names, as well as to see what the
colours look like, is to fire up a colour chooser (like xcolorsel)
that both lists the colour names and shows a swatch of the colour
as well.
Whichever method you use to find X color names, remember that the
names, passed as arguments to XCOLOR, must be all one word, all in
lower case.
Note:
Both the colorname and the alias you give to XCOLOR may be
used with groff’s \m[<colorname>]
inline escape (the \m escape is used to set
text and rule colours). Thus, assuming an X-colorname
“mediumspringgreen” set with XCOLOR, and an alias,
“mygreen”, \*[mediumspringgreen],
\m[mediumspringgreen], \*[mygreen] and
\m[mygreen] are all equivalent. Furthermore, both the
colorname and the alias can be given as an argument to groff’s
primitive
request, .gcolor (which does the same thing as
\m[<colorname>]).
The colorname initialized with XCOLOR but not the
alias may also be used with groff’s inline escape,
\M[<colorname>], and the corresponding primitive,
.fcolor, both of which set the “fill” colour
for solid graphical objects. If you need a colour initialized with
XCOLOR for \M or .fcolor, you MUST give the
full colorname; the alias won’t work.
Invoking a color
Macro: COLOR <colorname>
Inline: \*[<colorname>]
Once you've told mom about a colour (via
NEWCOLOR
or
XCOLOR,
you use either the macro COLOR or the
inline escape,
\*[<colorname>], to cause mom to
set subsequent text in that colour. See the
example,
above, which shows both in action.
Note:
You can use the \*[<colorname>] inline escape in
any
document processing
macro that takes a
string argument.
However, you must remember to reset the colour at the end of the
argument (typically with \*[black]) unless you want all
subsequent invocations of that particular macro to be colourized.
Furthermore, if you use \*[<colorname>] in the
string argument passed to
HEAD,
SUBHEAD
or
PARAHEAD,
and you've requested that any of these types of heads be numbered,
the numbers themselves will not be coloured, only the text you
passed the macro. If you wish the numbers to be colourized as well,
you must explicitly tell mom that you wish all of the head(s),
subhead(s) or parahead(s), including the numbers, colourized by
invoking the appropriate
control macro.
For colorizing underscored text, see
Colorizing underscored text
in the notes at the end of
UNDERSCORE.