Mom -- Colour

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# Coloured text

Introduction to coloured text
Index of colour macros

## Introduction to coloured text

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 "black", "BLACK", "white" and "WHITE" for you.

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

Please note: Mom's colour support is for text only. She doesn't support "fill" (or "background") colour for drawn objects. Please also note that 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.

### Index of colour macros

- NEWCOLOR
- XCOLOR
- COLOR
- \*[<colorname>] inline escape

### 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 RGB (3 components, red green blue), CYM (3 components cyan yellow magenta), CMYK (4 components cyan magenta yellow black) or 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 "1 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.)

### 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 color name> [<alias>]
*<X color name> 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 legal 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, "blue" (and "blue1") are the brightest forms of (rgb) blue; "blue2", "blue3" and "blue4" are increasingly darker shades of the same blue. 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.

### 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.

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