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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. Afterwards, 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 colourise 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 initialize the colour, black. Mom predefines it for you.

For information on using colour during document processing, see Colour support in document processing.

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 \*[<colour 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
RGB (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 CMY #0000FF \"or ##0000FFFF0000 or "0 0 1" .NEWCOLOR YELLOW CMYK #0000FF00 \"or ##00000000FFFF0000 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, \*[<colourname>], or the macro COLOR. (See the example, above.)

<X colourname> must be all one word, all lower case.
(See Finding X colour 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 initialize the X colour, coral, all you have to do is enter
.XCOLOR coral Afterwards
.COLOR coral will colourise subsequent text coral until you instruct mom to return to black, or some other pre-defined, initialized colour. (The inline escape \*[coral] will equally colourise 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 colours, 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 colours.

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 colour 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 colour names, remember that the names, passed as arguments to XCOLOR, must be all one word, all in lower case.

Inline: \*[<colourname>]

Once you’ve told mom about a colour (via NEWCOLOR or XCOLOR, you use either the macro COLOR or the inline escape, \*[<colourname>], to cause mom to set subsequent text in that colour. See the example, above, which shows both in action.

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