Solaris supports two types of font representation: outline fonts and bitmap fonts. To display a letter from an outline font, the server scales and rotates only the outline of the character. This repositioned outline is then rendered into pixel form (bitmap) for display on the screen. This rendered bitmap is also stored in the glyph cache for reuse.
Because certain font sizes occur frequently, they are also kept in separate files in pre-rendered bitmap form. This saves the server from having to scale and render them. However, the resulting bitmap fonts can be displayed in only one size and orientation. Some of the fonts have also been hand-tuned to look better and be more readable. As they are encountered, these bitmaps are also placed in the glyph cache. The recommended bitmap format is the portable compiled format (.pcf).
The /usr/openwin/bin directory contains the following tools to convert fonts between the outline and bitmap font representation, as well as between various bitmap formats. See the corresponding man pages for more detailed information.
As illustrated in Table 4-4, many bitmap font file formats are architecture-dependent binary files. They cannot be shared between machines of different architectures (for example, between SPARC and IA).
Table 4-4 Bitmap Font Binaries
The Solaris environment contains compressed .pcf files (files with .pcf.Z extensions). You can uncompress these if you want. If you add fonts to your system, you can either compress the files or not. Use uncompressed files if you want the fonts to display somewhat faster. Leave the files compressed if you want to conserve disk space. For more information, see the compress(1) man page.
The Solaris environment automatically replaces some outline fonts with bitmap fonts when the size is appropriate. This improves performance, and in some cases improves the aesthetics and readability of the text. There may be several sizes at which replacement occurs for a given outline font.
Currently in DPS, the .pcf bitmap format is substituted for F3 outline fonts, Type1 and TrueType fonts. Substitution occurs when there is no rotation, the requested pixel size is within one half of a pixel of the .pcf font size, and the .pcf font is a resource in a .upr (PostScript resource) file. The .pcf format can be substituted for all scalable versions of the fonts mentioned above.