The FontMap module handles two naming systems, but has scope to be expanded with more in the future. The module specifically handles the RISC OS naming system, and the Windows naming system. Although the system is called 'Windows', it is actually a more widely adopted naming scheme due to the specification of fonts on websites and the availability of fonts.

There is another naming system which is not supported by FontMap at present - the PostScript font naming system. This is partially catered for by the Printer driver system, so is not explicitly handled in the FontMap module.

The font naming systems use the following values: RISC OS Windows Reserved

Fonts consist of four major features which can be recognised by the FontMap module:

The font family name, for example 'Homerton' or 'Helvetica'. The weight of the font, for example 'Bold', or 'Light'. The obliqueness of the font, which is commonly given as 'Oblique' or 'Italic'. The stretchedness of the font, which is commonly given as 'Condensed' or 'Expanded'.

The properties recognised here take their inspiration from the SVG 'font-face' element, which is itself based on the CSS 2 '@font-face' facility.

The font family generally groups fonts which have the stylistic design. How characters are formed, and how they relate to one another is what distinguishes the families of fonts. The FontMap module can perform a mapping between these font families where they are sufficiently similar. This is necessary because RISC OS does not use the same standardised names for its fonts as are used elsewhere.

For example, the RISC OS font family has similar stylistic design to the font used elsewhere as 'Helvetica'. The FontMap module allows a translation between these font names to produce an approximation of the original intent. This translation is (commonly) bidirectional, so that as well as importing content which uses the foreign naming schemes to RISC OS, the RISC OS font names can be translated to the equivalent foreign font names.

The weight of a font indicates the relative darkness or heaviness of the text. There is no standardised naming scheme for the weights of gonts, but there are commonly used weight names that are used in a self-consistent continuum within a family.

The FontMap module assigns these weights values which can be compared and used to understand the relationship between different fonts within the family.

Don't care - a value that can be requested when any suitable weight is accepted Thin Extra light Light Regular Medium Semi-bold Bold Extra bold Black

The obliqueness of a font indicates whether the font is set at an angle (which is usually used for emphasis), or not. Within the FontMap module this is a binary choice - either the font is at an angle or it is not.

Stylistically, the font may differentiate the manner in which it is angled. Generally, 'Oblique' fonts are the same as the non-oblique font, but with a simple transformation applied to make the top of the font lean rightwards. 'Italic' fonts are those that have been specially crafted to look different when set at an angle, sometimes with different ornamentation or flourishes, or with different emphasis on components of the characters.

The FontMap module does not differentiate between 'Italic' and 'Oblique' variants of a font, but treats both as the same state in its values. The FontMap module has no support for the degree to which the font is angled, and has no support for reverse leaning fonts. The values used by the module for obliqueness are:

Don't care - a value that can be requested when any suitable obliqueness is accepted Plain, not at any angle Oblique or italic

The stretch of a font gives a relative measure of how much wider or thinner a font is than others within the same family. As with the font weight names, there is no standardised naming for these features, but a continuum within a given font is usually expected.

The values used by FontMap are:

Don't care - a value that can be requested when any suitable stretch is accepted Ultra-condensed Extra-condensed Condensed Semi-condensed Normal Semi-expanded Expanded Extra-expanded Ultra-expanded

The Font Mapping file describes the translation between formats. It is configured through the variable.

The translation file is a text file containing lines for mappings between the formats. The file has a simple line oriented format, which uses '#' character prefix for comments. Other lines consist of:

The source system format, either an 'R' or a 'W' for RISC OS or Windows format of font family. The conversion type, either a '-' or a '>'. '-' indicates a bidirectional conversion between the source and destination system formats. '>' indicates a unidirectional conversion. The destination system format, either an 'R' or a 'W' for RISC OS or Windows format of font family. A colon (':') separator. The source font family name. A colon (':') separator. The destination font family name.

Described in ABNF the format is:

By default the FontMap module will use a font mapping file that looks similar to the following:

# Foreign font mappings # # Cut down form as fallback for ROM. # Standard mappings for RISC OS and Windows fonts R-W:Trinity:Times New Roman R-W:Homerton:Arial W>R:Helvetica:Homerton R-W:Corpus:Courier New

The SWI provides a means of applying these properties and mappings to font names. The FontMap module will try to satisfy requests using the information available to it from the FontManager and the font mapping file.

The translation process goes through simple steps to translate the fonts:

Identify the input font and its properties in the input font system. This means extracting the font properties from the name, and identifying the font family. Replace any of the properties from the input font with those supplied by the user. Map the font family name from the input system to the output system. Search the output font system for a suitable font name for the closest match to the font required. Return the result to the caller.

This process is expected to be inexact when translating between font systems. Different property inputs may match multiple fonts - for example, if an Extra Bold weight font is requested, but only Bold is available, the Bold will be returned, just as it would if Bold weight had been requested.

When translating RISC OS fonts, the FontMap module is able to synthesise oblique fonts by using a font transformation matrix. This is only performed when there is no suitable oblique or italic font.