2. Terminology

This section defines terminology used with the Font library. The definitions used here are specific to this library and may differ from the ordinary meaning of the terms.

2.1. Terms Related to Characters and Text

The following table presents a summary of character-related and text-related terms.

Table 2-1. Character-Related and Text-Related Terms
Term Description
Letters The graphical shape to render. It includes both the visually recognizable graphic image and the white space surrounding it.
Encoding A numerical value assigned to each character to facilitate handling by computer systems.
Character Sets A set of characters and their associated character codes.
Text Encoding A method of converting or arranging character codes so that a string is represented as a byte array.
ISO 8859-1

A character set formed by adding some extended Latin characters and symbols to the ASCII character set; also called Latin-1.

The range of character codes used is from 0x00 to 0xFF, but 0x00 to 0x1F and 0x80 to 0x9F are allocated to control characters that cannot be displayed.

CP1252 (Code Page 1252) An extended Latin character set defined by Microsoft for Windows. In this set, the characters in the range 0x80 to 0x9F, which are allocated to control characters in ISO 8859-1, are replaced with displayable characters, so all of the displayable characters in ISO 8859-1 can also be displayed by CP1252.
JIS X 0201 A Japanese character set defined in the JIS standards. It includes Japanese hiragana, katakana, and kanji as full-width characters.
JIS X 0208 A Japanese character set defined in the JIS standards. It includes ASCII and half-width katakana as half-width characters.
Shift JIS The standard character encoding in Japanese environments. The characters included in JIS X 0201 and JIS X 0208 can be used in this encoding.
Unicode A character system intended to represent all characters used in the world in a single character set. It includes definitions for both character sets and character encodings.
UTF-16

A character encoding defined under Unicode. In this encoding all characters are represented with two bytes, so it includes almost all other character encodings, but is not compatible with ASCII.

Depending on the endianness, it may use the notation UTF16-BE or UTF16-LE.

UTF-8 A character encoding defined under Unicode. In this encoding the number of bytes corresponding to one character depends on the character. ASCII characters are represented with one byte, so this encoding is compatible with ASCII, in contrast to UTF-16.

2.2. Terms Related to Glyphs

A glyph is defined to be a visually recognizable shape of a character. This section describes terms related to glyphs.

Figure 2-1. below illustrates parameters involved in the display of glyphs. The yellow regions are the glyphs, while the characters include both the glyphs and the surrounding green regions. Parameters of the glyphs that are supplied by the Font library are indicated in black, parameters of the fonts that are supplied by the Font library are indicated in blue, and parameters that are set by the application when displaying the glyphs as strings are indicated in red.

Figure 2-1. Glyphs

Character width, character spacing, left space width, right space width, ascender line, baseline position, cell height, ascent, descent, font height, line feed width, baseline, descender line

Table 2-2. Glyph-Related Terms
Term Description
Glyph Images A term referring to a glyph that emphasizes its aspect of being a graphic image. It may also be called a cell.
Cell height The height of a glyph image. This is common to the entire font.
Glyph width The width of a rectangle circumscribing the glyph. In the figure, the width of the yellow region.
Left space width The width of the space between the glyph and the immediately previous character.
Right space width The width of the space between the glyph and the immediately subsequent character.
Character width The width of the character. The sum of the glyph width and the left and right space widths.
Character width information Information indicating the width of a character. Consists of the following four pieces of information: the left space width, the right space width, the glyph width and the character width.
Baseline The position serving as the base in the vertical direction for all glyphs when lining up characters horizontally (that is, when rendering characters).
Ascender line A line along the upper edge of the region to be occupied by the string.
Descender line A line along the lower edge of the region to be occupied by the string.
Ascent The distance from the baseline to the ascender line.
Descent The distance from the baseline to the descender line.
Font height The distance from the ascender line to the descender line.
Font width The character width shared by all characters in a font. This width serves as the basis for the tab width.

2.3. Terms Related to Font Resources

The following table presents terms related to font data and other font resources.

Table 2-3. Terms Related to Font Resources
Term Description
BCFNT (Binary Ctr FoNT) Ordinary font data used in the Font library. Also, the extension for files that contain this font data.
BCFNA (Binary Ctr FoNt Archived)

Compressed font data used in the Font library. Also, the extension for files that contain this font data.

You can extract and decompress individual glyph sets as needed from these archives. . These archives are used when the fonts to be displayed are grouped by language, or when you want to switch only some fonts to a different typeface.

Font resource Ordinary font data used in the Font library. Synonymous with BCFNT.
Archived font Compressed font data used in the Font library. Synonymous with BCFNTA.
ctr_FontConverter A Windows tool used to create BCFNT and BCFNA data. Both a GUI version and command-line version are provided.
Alternate character A substitute character used when information for the requested character is not contained within a font.

2.3.1. Glyph Groups

A glyph group is defined as a glyph set that is subdivided into groups. In addition, a set of glyph groups is called a group set.

The Font library provides a feature for constructing a font by freely selecting and combining any of the groups within a group set. For example, from a group set comprising the four groups “ascii,” “latin,” “greek,” and “cyrillic,” it is possible to construct a font containing only the glyphs required to display text for languages that use the Latin alphabet by combining “ascii” and “latin,” or a font for languages that use the Cyrillic alphabet by combining “ascii” and “cyrillic.”

Figure 2-2. Examples of Glyph Group

ascii latin greek cyrillic

 

2.3.2. Sheets

A sheet is defined as a texture object upon which glyph images are drawn. One texture object corresponds to one sheet. Multiple glyph images can be arranged on a single sheet.

Figure 2-3. Examples of Sheets

 

2.4. Other Terms

The following table presents other terms related to the Font library.

Table 2-4. Other Terms
Term Description
Tagged strings

Strings that contain instructions related to rendering text.

The Font library provides a framework for processing tagged strings. The actual processing of tags embedded in strings must be handled by the application.


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