Dissecting a Font (Mastering Perl/Tk)

3.2. Dissecting a Font

In the font viewer, we see that the Entry's font is changed with the -font option using an anonymous array. From this we know a font consists of the following things:

Family

If you are used to working with fonts on a Unix system, you are probably familiar with X Logical Font Descriptions (XFLD). This is the dash-delimited format used for fonts under X, for example:

*-helvetica-bold-r-*-*-*-240-*-*-*-*-*-*

This font description indicates a 24-point bold Helvetica font with Roman slant. The field order is as follows: -foundry-family-weight-slant-sWdth-adstyl-pixelsize-pointsize-resx-resy-spacing-avgWidth-registry-encoding.

When specifying a font in XLFD notation, an asterisk means you don't care what is used for that value, and the system will choose a default for you.

While a full description of X fonts is beyond the scope of this book, there are a few things you should know. First, it is entirely acceptable to specify a font in XLFD notation under either Unix or Windows. The code is:

font => '-*-helvetica-bold-r-*-*-*-240-*-*-*-*-*-*'

When you use this format under Unix, you get exactly what you ask for. Every field is honored. Under Windows, only family, weight, slant, pixelsize, and pointsize are honored. All the other fields are ignored.

If you would like to learn more about fonts under X, a good beginner's guide and bibliography may be found in "The X Window User HOWTO" by Ray Brigleb. This document may be found in many, many places on the Web, but the definitive location is http://www.linuxdoc.org/HOWTO/XWindow-User-HOWTO.html.