Chapter 13. Examples of I18N

100

  a font with charset of JISX0208.1983 0 or JISX0208.1990 0, and

  a font with charset of JISX0201.1976 0

are used.

1

Again assume that

GetFont

received a string of   adobe helvetica bold r normal * 

120 * * * * * *  as

font >name

. This string is a very likely specification of font. Actually, I got the

example from the default title font for TWM. Now review the behavior of

XLoadQueryFont()

.

Since it always gets at most one font, it can succeed or fail. However, since

XCreateFontSet()

may get multiple fonts, it may success only to get a part of the set of requred fonts. The assumed

calling of

XCreateFontSet()

with the

font >name

in

ja_JP.eucJP

locale goes into just such

a situation. For usual systems, only a font for ISO8859 1 or JISX0201.1976 0 is available.

2

It is

easy to solve this situation. Unlike

XLoadQueryFont()

,

XCreateFontSet()

can take a list of

patterns of fonts with wildcards.

XCreateFontSet()

chooses necessary fonts from the set of

fonts which match the patterns.  *  can match all fonts. This works for character sets for which

the given

font >name

failed to match any fonts.

There were two solutions I imagined.

  Adding  ,*  for all font specifications in the configuration file.

  Adding  ,*  just before calling

XCreateFontSet()

. (the solution I took.)

The first solution may fail because users can rewrite the configuration file. Though it is likely

that a user knows necessary character sets for the encoding (s)he uses, the second way is safer.

And more, recent window managers are coming to support themes where a set of configuration

is packaged and distributed, just as in

http://www.themes.org/

. It is very unlikely that all

developers of these themes know this problem and adds  ,*  for every font specifications. Thus,

window managers which support themes must take the 2nd solution, though TWM does not

support themes.

Which font exactly is choosed for wild cards? It depends on the configuration of X Window

System. I imagine that the first font in the list generated by

xlsfonts

. You may think the choice

of the font should be cleverer. It would be adequate to say that  ,*  mechanism is not less cleverer;

it has entirely no intelligence. It is not clever at all. Yes, though I didn't implement it to TWM, I

also wrote a cleverer guessing mechanism.

3

1

Read

/usr/X11R6/lib/X11/locale/ja/XLC_LOCALE

for detail.

2

In such a case,

XCreateFontSet()

does not fail. Instead, it returns informations on missing fonts.

3

I implemented cleverer mechanism to window managers such as Blackbox, Sawfish, and so on where I think

beauty is important than simplicity. The intended algorithm is:

  Choose a font with similar pixel sizes.

  If availavle, choose a font with similar weight and slant.