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7. Fonts and Colors

There are a lot of tricks to the fonts and colors used in X. They are not quite as simple as in some other systems, for instance, the font is not just a one-word name. You specify these resources quite explicitly, and it seems rather complex at first, but with a little explanation you'll be a whiz in no time.

7.1 Fonts Demystified

The X Logical Font Description ("XLFD") is the full name for a font. It consists of the following fields:

In light of this chaos, the program xfontsel (the default X Window font selection program) will come in enormously useful to you. Try launching it right now. You will see a strange nothing helpful in the main window, but try holding the left button down on the fndry button. If all your fonts are in order, you will see a menu of selections such as adobe and b&h and bitstream and so forth. Select one such as b&h and you will notice that the font in the lower window changes to something intelligible. This is generally the way you will select fonts with this program, starting from the left, which is the most general selection, and moving toward the right, to the more specific options. Selecting an option toward the rightmost end will not make much sense before the foundry, for instance, is selected, because the options are generally ordered by their dependence on each other.

When you go to select from the fmly selection, you will see most of the options greyed out, and only three remaining. That means that these three are the only families of font made by this foundry. Some families appear under more than one foundry, for instance, both Adobe and Bitstream make a variation of the Courier font. Now you can select the wght, and so forth. After you get far enough you will have narrowed it down to the font that you want. You don't necessarily have fill in all the options to choose a single font, there's not that many fonts on your system! The options that you do not select will be represented by a * indicating that any option will do in that spot.

When you are happy with your font selection, you can hit the select button, and your selection will be placed in the X clipboard, ready to be pasted into your document or whatever you are working on. For instance, go to your xterm window and type in something like xterm -font followed by an opening quotation mark. Then point to that spot on your screen, and click your middle mouse button (or click both the left and right, if you're middle-button impaired). This will paste the selection from the clipboard, which should be the font you just selected. Then enter the closing quote, and hit Enter. For instance, a nice big xterm with a Courier font specified would look like this: xterm -font "-adobe-courier-medium-r-*-*-14-*-*-*-*-*-*-*"A fresh xterm should the pop up using the font that you selected.

The utility xfd is very helpful for examining a font. If you launch it with a command line such as xfd -fn fixed, it will show you the character set for the font, much like the keycaps utility on a Macintosh. Note that you can also limit the number of fonts that you want xfontsel to display with the command line option -pattern, followed by a quoted font specification, as discussed above.

7.2 Font Aliases and Configuration

Sometimes it gets tiresome to remember all of the long font names, and very impractical too. Luckily, it is not necessary to type in a hundred keystrokes or so just to get the font name you want, for X provides something called font aliases.

If you look in the directory /usr/X11R6/lib/fonts/misc/fonts.alias, you will find shortcut names for many of the fonts. For example, 8x16 is listed as a shortcut for -sony-fixed-medium-r-normal--16-120-100-100-c-80-iso8859-1, and anywhere you enter 8x16 as an X font resource or at a command line for a font name, the long version of the font will be substituted. The 75dpi and 100dpi directories have similar aliases to take advantage of, on most systems the Lucida Sans font has a nice shortcut.

If you add fonts or aliases to your system, you will have to issue a few commands (probably as root). If you add fonts, you will have to issue the following two commands (these are examples, you will have to put in the correct directory, or perhaps leave it off altogether, to have your fonts re-read correctly. 

 mkfontdir /usr/lib/X11/fonts/misc
 xset fp rehash

If you change the alias file for a font, you may only have to issue the last command above, but it may be a good idea to issue them both, to be sure. With the xset command you can explicitly issue a font path you wish the server to use, you can delete a specific directory from your font path, see the man page for more information.

7.3 Colors

Let's go back to our terminal window and try some more things. Try opening an xterm with a command line like the following: 

 xterm -fg darkslateblue -bg red3 &

While that window may not be pretty, and you may not do much of your best work in it, it demonstrates one interesting theme of X, the names of the colors. While not very precise, this is a nice way to remember the colors more easily than remembering a series of hexadecimal numbers. Note that color names are never case-sensitive.

If you're interested in the gory details, or want to see the samples, or even want to replace those silly color names with your own for some strange reason, you can find the file listing all the colors with their hexadecimal representation in /usr/X11R6/lib/X11/rgb.txt on your system. There are also some extremely useful utilities with names like xcolorsel and such. They can be found in the usual locations, on SunSite and elsewhere.

A more precise way of specifying colors is through the numerical definition. This consists of a color space name and a set of values in the following syntax:

<colorspace-name>:<value>/.../<value>

An RGB Device, which you will most likely be using, is specified with the prefix "rgb:" and has the following syntax:

rgb:<red>/<green>/<blue> , where <color> is a 1 to 4 digit hexadecimal number.

As an example, you might represent the color red with rgb:ffff/0/0. For backward compatibility, you can also specify red with a syntax such as #ff0000 or #ffff00000000, and you will likely be seeing that (older) syntax a lot.

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