/***@page m17nDatabaseFormat Data Format of the m17n database This section describes formats of data in the m17n database. @section dbformat General format The mdatabase_load () function returns the data specified by tags in the form of plist if the first tag is not @c Mchartable nor @c Mcharset. The keys of the returned plist are limited to Minteger, Msymbol, Mtext, and Mplist. The type of the value is unambiguously determined by the corresponding key. If the key is Minteger, the value is an integer. If the key is Msymbol, the value is a symbol. And so on. A number of expressions are possible to represent a plist. For instance, we can use the form (K1:V1, K2:V2, ..., Kn:Vn) to represent a plist whose first property key and value are K1 and V1, second key and value are K2 and V2, and so on. However, we can use a simpler expression here because the types of plists used in the m17n database are fairly restricted. Hereafter, we use an expression, which is similar to S-expression, to represent a plist. (Actually, the default database loader of the m17n library is designed to read data files written in this expression.) The expression consists of one or more elements. Each element represents a property, i.e. a single element of a plist. Elements are separated by one or more whitespaces, i.e. a space (code 32), a tab (code 9), or a newline (code 10). Comments begin with a semicolon (;) and extend to the end of the line. The key and the value of each property are determined based on the type of the element as explained below. EXAMPLE Here is an example of plist that is written in the expression explained above. @verbatim abc 123 (pqr 0xff) "m\"text" (_\\_ ("string" xyz) -456) @endverbatim It represents the following plist: @verbatim (Msymbol:abc, Minteger:123, Mplist:(Msymbol:pqr, Minteger:255), Mtext:m"text, Mplist:(Msymbol:_\_, Mplist:(Mtext:string, Msymbol:xyz), Minteger:-456)) @endverbatim @section fontenc Font Encoding The m17n library loads information about the encoding of each font form the m17n database by the tags \. The plist format of the data is as follows: @verbatim FONT-ENCODING ::= PER-FONT-INFO * PER-FONT-INFO ::= '(' FONT-SPEC ENCODING ')' FONT-SPEC ::= '(' [ FOUNDRY FAMILY [ WEIGHT [ STYLE [ STRETCH [ ADSTYLE ] ] ] ] ] REGISTRY ')' @endverbatim @c FOUNDRY to @c REGISTRY are symbols specifying the corresponding XLFD font name fields. Omitted symbols are regarded as @c nil, and @c nil means a wild card. For instance, this @c FONT-SPEC: @verbatim (nil alice0\ lao iso8859-1) @endverbatim should be applied to all fonts whose family is "alice0 lao", and registry is "iso8859-1". @c ENCODING is a symbol representing a charset. A font matching @c FONT-SPEC supports all characters of the charset, and a character code is mapped to the corresponding glyph code of the font by this charset. @section fontsize Font Resizing In some case, a font contains incorrect information about its size (typically in the case of a hacked TrueType font), which results in a bad text layout when such a font is used in combination with the other fonts. To overcome this problem, the m17n library loads information about font-size correction from the m17n database by the tags \. The plist format of the data is as follows: @verbatim FONT-RESIZE ::= PER-FONT-INFO * PER-FONT-INFO ::= '(' FONT-SPEC RESIZE-RATIO ')' FONT-SPEC ::= '(' [ FOUNDRY FAMILY [ WEIGHT [ STYLE [ STRETCH [ ADSTYLE ] ] ] ] ] REGISTRY ')' @endverbatim The meanings of @c FOUNDRY to @c REGISTRY are the same as @e Font @e Encoding. @c RESIZE-RATIO is an integer number specifying by percentage how much the font-size must be adjusted. For instance, this @c PER-FONT-INFO: @verbatim ((devanagari-cdac) 150) @endverbatim means that, to use a font of registry "devanagari-cdac" with a specific size, we have to open an 1.5 times bigger one. @section fontset Fontset The m17n library loads a fontset definition from the m17n database by the tags \. The plist format of the data is as follows: @verbatim FONTSET ::= PER-SCRIPT * PER-CHARSET * FALLBACK * PER-SCRIPT ::= '(' SCRIPT PER-LANGUAGE + ')' PER-LANGUAGE ::= '(' LANGUAGE FONT-SPEC-ELEMENT + ')' PER-CHARSET ::= '(' CHARSET FONT-SPEC-ELEMENT + ')' FALLBACK ::= FONT-SPEC-ELEMENT FONT-SPEC-ELEMENT ::= '(' FONT-SPEC [ FLT-NAME ] ')' FONT-SPEC ::= '(' [ FOUNDRY FAMILY [ WEIGHT [ STYLE [ STRETCH [ ADSTYLE ] ] ] ] ] REGISTRY ')' @endverbatim @c SCRIPT is a symbol of script name (e.g. latin, han) or @c nil. @c LANGUAGE is a two-letter symbol of language name code defined by ISO 639 (e.g. ja, zh) or @c nil. The meanings of @c FOUNDRY to @c REGISTRY are the same as @e Font @e Encoding. @c FLT-NAME is a name of @ref flt. For instance, this @c PER_SCRIPT: @verbatim (han (ja ((jisx0208.1983-0))) (zh ((gb2312.1980-0))) (nil ((big5-0)))) @endverbatim instructs the rendering engine to use a font of registry "jisx0208.1983-0" for a "han" character that has @c Mlanguage text propert "ja" if the character is in the repertories of such fonts. Otherwise, try a font of registry "gb2312.1980-0" or "big5-0". If a "han" character does not have @c Mlangauge text property, try all three fonts. @section flt Font Layout Table Usually, the rendering engine converts character codes of into glyph codes one by one by consulting information about encoding of each selected font. But, for rendering a text that requires complicated layouting (e.g. Thai and Indic), such an one to one conversion is not sufficient. In addition, some glyphs must be shifted 2-dimensionally on the screen. For such a case, a font layout table (FLT in short) must be used. A FLT can contain the information equivarent to OpenType Layout Table (CMAP, GSUB, and GPOS) in addition to the information about how to extract a grapheme cluster and how to re-order characters. The m17n library loads a FLT from the m17n database by the tags \. The plist format of the data is as follows: @verbinclude flt.txt @section im Input Method @verbinclude im.txt */ ////