To accurately represent a printer font on the screen, the font vendor must make available a reasonable range of screen fonts. However, each screen font uses memory. Therefore, a font vendor should carefully weigh performance against a large screen-font variety.
The most important factor to consider when creating screen-font files is memory use. Fewer and smaller screen fonts use less memory, but may degrade the WYSIWYG quality of the display.
Other factors to consider include the following:
Legibility Threshold. There is a certain size at which the fonts are difficult, if not impossible, to read. For most screens, the value is 6 lines. For high-resolution screens, the value is around 9–10 lines. Therefore, it does not make sense to provide fonts below these sizes.
Doubling and Tripling. The screen driver may double or triple a small-size font to take the place of an unavailable large font. For example, it may double an 18-line font to make a 36-line font, or it may triple a 24-line font to make a 72-line font. Doubling is not attractive, but acceptable and difficult to avoid. Tripling is unacceptable and can be avoided by providing a well-chosen range of screen line sizes.
Specific Applications. The application can control how the screen driver will select a font for such things as text greeking, doubling and tripling, vector font substitution, and downsizing to match widths.