thctype.h File Reference

Thai character classifications. More...

## Functions

int | th_istis (thchar_t c)
| Is the character a valid TIS-620 code?
int | th_isthai (thchar_t c)
| Is the character a Thai character?
int | th_iseng (thchar_t c)
| Is the character an English character?
int | th_isthcons (thchar_t c)
| Is the character a Thai consonant?
int | th_isthvowel (thchar_t c)
| Is the character a Thai vowel?
int | th_isthtone (thchar_t c)
| Is the character a Thai tone mark?
int | th_isthdiac (thchar_t c)
| Is the character a Thai diacritic?
int | th_isthdigit (thchar_t c)
| Is the character a Thai digit?
int | th_isthpunct (thchar_t c)
| Is the character a Thai punctuation?
int | th_istaillesscons (thchar_t c)
| Is the character a Thai consonant that fits the x-height?
int | th_isovershootcons (thchar_t c)
| Is the character a Thai consonant with stem above ascender?
int | th_isundershootcons (thchar_t c)
| Is the character a Thai consonant with stem below baseline?
int | th_isundersplitcons (thchar_t c)
| Is the character a Thai consonant with split part below baseline?
int | th_isldvowel (thchar_t c)
| Is the character a Thai leading vowel?
int | th_isflvowel (thchar_t c)
| Is the character a Thai following vowel?
int | th_isupvowel (thchar_t c)
| Is the character a Thai upper vowel?
int | th_isblvowel (thchar_t c)
| Is the character a Thai below vowel?
int | th_chlevel (thchar_t c)
| Position for rendering:
int | th_iscombchar (thchar_t c)
| Is the character a combining character?

## Detailed Description

Thai character classifications.

The Thai Standard Industrial Standards Institute (TIS) defined the Thai character set for using with computer named TIS-620. This character set is 8-bit encoded including both English and Thai characters. Aliases of TIS-620 are TIS620, TIS620-0, TIS620.2529-1, TIS620.2533-0 and ISO-IR-166.

The followings are the enconding values in hexadecimal, unicode values and their names.

    0x00   <U0000> NULL (NUL)
    0x01   <U0001> START OF HEADING (SOH)
    0x02   <U0002> START OF TEXT (STX)
    0x03   <U0003> END OF TEXT (ETX)
    0x04   <U0004> END OF TRANSMISSION (EOT)
    0x05   <U0005> ENQUIRY (ENQ)
    0x06   <U0006> ACKNOWLEDGE (ACK)
    0x07   <U0007> BELL (BEL)
    0x08   <U0008> BACKSPACE (BS)
    0x09   <U0009> CHARACTER TABULATION (HT)
    0x0A   <U000A> LINE FEED (LF)
    0x0B   <U000B> LINE TABULATION (VT)
    0x0C   <U000C> FORM FEED (FF)
    0x0D   <U000D> CARRIAGE RETURN (CR)
    0x0E   <U000E> SHIFT OUT (SO)
    0x0F   <U000F> SHIFT IN (SI)
    0x10   <U0010> DATALINK ESCAPE (DLE)
    0x11   <U0011> DEVICE CONTROL ONE (DC1)
    0x12   <U0012> DEVICE CONTROL TWO (DC2)
    0x13   <U0013> DEVICE CONTROL THREE (DC3)
    0x14   <U0014> DEVICE CONTROL FOUR (DC4)
    0x15   <U0015> NEGATIVE ACKNOWLEDGE (NAK)
    0x16   <U0016> SYNCHRONOUS IDLE (SYN)
    0x17   <U0017> END OF TRANSMISSION BLOCK (ETB)
    0x18   <U0018> CANCEL (CAN)
    0x19   <U0019> END OF MEDIUM (EM)
    0x1A   <U001A> SUBSTITUTE (SUB)
    0x1B   <U001B> ESCAPE (ESC)
    0x1C   <U001C> FILE SEPARATOR (IS4)
    0x1D   <U001D> GROUP SEPARATOR (IS3)
    0x1E   <U001E> RECORD SEPARATOR (IS2)
    0x1F   <U001F> UNIT SEPARATOR (IS1)
    0x20   <U0020> SPACE
    0x21   <U0021> EXCLAMATION MARK
    0x22   <U0022> QUOTATION MARK
    0x23   <U0023> NUMBER SIGN
    0x24   <U0024> DOLLAR SIGN
    0x25   <U0025> PERCENT SIGN
    0x26   <U0026> AMPERSAND
    0x27   <U0027> APOSTROPHE
    0x28   <U0028> LEFT PARENTHESIS
    0x29   <U0029> RIGHT PARENTHESIS
    0x2A   <U002A> ASTERISK
    0x2B   <U002B> PLUS SIGN
    0x2C   <U002C> COMMA
    0x2D   <U002D> HYPHEN-MINUS
    0x2E   <U002E> FULL STOP
    0x2F   <U002F> SOLIDUS
    0x30   <U0030> DIGIT ZERO
    0x31   <U0031> DIGIT ONE
    0x32   <U0032> DIGIT TWO
    0x33   <U0033> DIGIT THREE
    0x34   <U0034> DIGIT FOUR
    0x35   <U0035> DIGIT FIVE
    0x36   <U0036> DIGIT SIX
    0x37   <U0037> DIGIT SEVEN
    0x38   <U0038> DIGIT EIGHT
    0x39   <U0039> DIGIT NINE
    0x3A   <U003A> COLON
    0x3B   <U003B> SEMICOLON
    0x3C   <U003C> LESS-THAN SIGN
    0x3D   <U003D> EQUALS SIGN
    0x3E   <U003E> GREATER-THAN SIGN
    0x3F   <U003F> QUESTION MARK
    0x40   <U0040> COMMERCIAL AT
    0x41   <U0041> LATIN CAPITAL LETTER A
    0x42   <U0042> LATIN CAPITAL LETTER B
    0x43   <U0043> LATIN CAPITAL LETTER C
    0x44   <U0044> LATIN CAPITAL LETTER D
    0x45   <U0045> LATIN CAPITAL LETTER E
    0x46   <U0046> LATIN CAPITAL LETTER F
    0x47   <U0047> LATIN CAPITAL LETTER G
    0x48   <U0048> LATIN CAPITAL LETTER H
    0x49   <U0049> LATIN CAPITAL LETTER I
    0x4A   <U004A> LATIN CAPITAL LETTER J
    0x4B   <U004B> LATIN CAPITAL LETTER K
    0x4C   <U004C> LATIN CAPITAL LETTER L
    0x4D   <U004D> LATIN CAPITAL LETTER M
    0x4E   <U004E> LATIN CAPITAL LETTER N
    0x4F   <U004F> LATIN CAPITAL LETTER O
    0x50   <U0050> LATIN CAPITAL LETTER P
    0x51   <U0051> LATIN CAPITAL LETTER Q
    0x52   <U0052> LATIN CAPITAL LETTER R
    0x53   <U0053> LATIN CAPITAL LETTER S
    0x54   <U0054> LATIN CAPITAL LETTER T
    0x55   <U0055> LATIN CAPITAL LETTER U
    0x56   <U0056> LATIN CAPITAL LETTER V
    0x57   <U0057> LATIN CAPITAL LETTER W
    0x58   <U0058> LATIN CAPITAL LETTER X
    0x59   <U0059> LATIN CAPITAL LETTER Y
    0x5A   <U005A> LATIN CAPITAL LETTER Z
    0x5B   <U005B> LEFT SQUARE BRACKET
    0x5C   <U005C> REVERSE SOLIDUS
    0x5D   <U005D> RIGHT SQUARE BRACKET
    0x5E   <U005E> CIRCUMFLEX ACCENT
    0x5F   <U005F> LOW LINE
    0x60   <U0060> GRAVE ACCENT
    0x61   <U0061> LATIN SMALL LETTER A
    0x62   <U0062> LATIN SMALL LETTER B
    0x63   <U0063> LATIN SMALL LETTER C
    0x64   <U0064> LATIN SMALL LETTER D
    0x65   <U0065> LATIN SMALL LETTER E
    0x66   <U0066> LATIN SMALL LETTER F
    0x67   <U0067> LATIN SMALL LETTER G
    0x68   <U0068> LATIN SMALL LETTER H
    0x69   <U0069> LATIN SMALL LETTER I
    0x6A   <U006A> LATIN SMALL LETTER J
    0x6B   <U006B> LATIN SMALL LETTER K
    0x6C   <U006C> LATIN SMALL LETTER L
    0x6D   <U006D> LATIN SMALL LETTER M
    0x6E   <U006E> LATIN SMALL LETTER N
    0x6F   <U006F> LATIN SMALL LETTER O
    0x70   <U0070> LATIN SMALL LETTER P
    0x71   <U0071> LATIN SMALL LETTER Q
    0x72   <U0072> LATIN SMALL LETTER R
    0x73   <U0073> LATIN SMALL LETTER S
    0x74   <U0074> LATIN SMALL LETTER T
    0x75   <U0075> LATIN SMALL LETTER U
    0x76   <U0076> LATIN SMALL LETTER V
    0x77   <U0077> LATIN SMALL LETTER W
    0x78   <U0078> LATIN SMALL LETTER X
    0x79   <U0079> LATIN SMALL LETTER Y
    0x7A   <U007A> LATIN SMALL LETTER Z
    0x7B   <U007B> LEFT CURLY BRACKET
    0x7C   <U007C> VERTICAL LINE
    0x7D   <U007D> RIGHT CURLY BRACKET
    0x7E   <U007E> TILDE
    0x7F   <U007F> DELETE (DEL)
    0xA1   <U0E01> THAI CHARACTER KO KAI
    0xA2   <U0E02> THAI CHARACTER KHO KHAI
    0xA3   <U0E03> THAI CHARACTER KHO KHUAT
    0xA4   <U0E04> THAI CHARACTER KHO KHWAI
    0xA5   <U0E05> THAI CHARACTER KHO KHON
    0xA6   <U0E06> THAI CHARACTER KHO RAKHANG
    0xA7   <U0E07> THAI CHARACTER NGO NGU
    0xA8   <U0E08> THAI CHARACTER CHO CHAN
    0xA9   <U0E09> THAI CHARACTER CHO CHING
    0xAA   <U0E0A> THAI CHARACTER CHO CHANG
    0xAB   <U0E0B> THAI CHARACTER SO SO
    0xAC   <U0E0C> THAI CHARACTER CHO CHOE
    0xAD   <U0E0D> THAI CHARACTER YO YING
    0xAE   <U0E0E> THAI CHARACTER DO CHADA
    0xAF   <U0E0F> THAI CHARACTER TO PATAK
    0xB0   <U0E10> THAI CHARACTER THO THAN
    0xB1   <U0E11> THAI CHARACTER THO NANGMONTHO
    0xB2   <U0E12> THAI CHARACTER THO PHUTHAO
    0xB3   <U0E13> THAI CHARACTER NO NEN
    0xB4   <U0E14> THAI CHARACTER DO DEK
    0xB5   <U0E15> THAI CHARACTER TO TAO
    0xB6   <U0E16> THAI CHARACTER THO THUNG
    0xB7   <U0E17> THAI CHARACTER THO THAHAN
    0xB8   <U0E18> THAI CHARACTER THO THONG
    0xB9   <U0E19> THAI CHARACTER NO NU
    0xBA   <U0E1A> THAI CHARACTER BO BAIMAI
    0xBB   <U0E1B> THAI CHARACTER PO PLA
    0xBC   <U0E1C> THAI CHARACTER PHO PHUNG
    0xBD   <U0E1D> THAI CHARACTER FO FA
    0xBE   <U0E1E> THAI CHARACTER PHO PHAN
    0xBF   <U0E1F> THAI CHARACTER FO FAN
    0xC0   <U0E20> THAI CHARACTER PHO SAMPHAO
    0xC1   <U0E21> THAI CHARACTER MO MA
    0xC2   <U0E22> THAI CHARACTER YO YAK
    0xC3   <U0E23> THAI CHARACTER RO RUA
    0xC4   <U0E24> THAI CHARACTER RU
    0xC5   <U0E25> THAI CHARACTER LO LING
    0xC6   <U0E26> THAI CHARACTER LU
    0xC7   <U0E27> THAI CHARACTER WO WAEN
    0xC8   <U0E28> THAI CHARACTER SO SALA
    0xC9   <U0E29> THAI CHARACTER SO RUSI
    0xCA   <U0E2A> THAI CHARACTER SO SUA
    0xCB   <U0E2B> THAI CHARACTER HO HIP
    0xCC   <U0E2C> THAI CHARACTER LO CHULA
    0xCD   <U0E2D> THAI CHARACTER O ANG
    0xCE   <U0E2E> THAI CHARACTER HO NOKHUK
    0xCF   <U0E2F> THAI CHARACTER PAIYANNOI
    0xD0   <U0E30> THAI CHARACTER SARA A
    0xD1   <U0E31> THAI CHARACTER MAI HAN-AKAT
    0xD2   <U0E32> THAI CHARACTER SARA AA
    0xD3   <U0E33> THAI CHARACTER SARA AM
    0xD4   <U0E34> THAI CHARACTER SARA I
    0xD5   <U0E35> THAI CHARACTER SARA II
    0xD6   <U0E36> THAI CHARACTER SARA UE
    0xD7   <U0E37> THAI CHARACTER SARA UEE
    0xD8   <U0E38> THAI CHARACTER SARA U
    0xD9   <U0E39> THAI CHARACTER SARA UU
    0xDA   <U0E3A> THAI CHARACTER PHINTHU
    0xDF   <U0E3F> THAI CHARACTER SYMBOL BAHT
    0xE0   <U0E40> THAI CHARACTER SARA E
    0xE1   <U0E41> THAI CHARACTER SARA AE
    0xE2   <U0E42> THAI CHARACTER SARA O
    0xE3   <U0E43> THAI CHARACTER SARA AI MAIMUAN
    0xE4   <U0E44> THAI CHARACTER SARA AI MAIMALAI
    0xE5   <U0E45> THAI CHARACTER LAKKHANGYAO
    0xE6   <U0E46> THAI CHARACTER MAIYAMOK
    0xE7   <U0E47> THAI CHARACTER MAITAIKHU
    0xE8   <U0E48> THAI CHARACTER MAI EK
    0xE9   <U0E49> THAI CHARACTER MAI THO
    0xEA   <U0E4A> THAI CHARACTER MAI TRI
    0xEB   <U0E4B> THAI CHARACTER MAI CHATTAWA
    0xEC   <U0E4C> THAI CHARACTER THANTHAKHAT
    0xED   <U0E4D> THAI CHARACTER NIKHAHIT
    0xEE   <U0E4E> THAI CHARACTER YAMAKKAN
    0xEF   <U0E4F> THAI CHARACTER FONGMAN
    0xF0   <U0E50> THAI DIGIT ZERO
    0xF1   <U0E51> THAI DIGIT ONE
    0xF2   <U0E52> THAI DIGIT TWO
    0xF3   <U0E53> THAI DIGIT THREE
    0xF4   <U0E54> THAI DIGIT FOUR
    0xF5   <U0E55> THAI DIGIT FIVE
    0xF6   <U0E56> THAI DIGIT SIX
    0xF7   <U0E57> THAI DIGIT SEVEN
    0xF8   <U0E58> THAI DIGIT EIGHT
    0xF9   <U0E59> THAI DIGIT NINE
    0xFA   <U0E5A> THAI CHARACTER ANGKHANKHU
    0xFB   <U0E5B> THAI CHARACTER KHOMUT

Thai characters consist of 44 consonants, vowels, tonemarks, diacritics and Thai digits. Thai vowels are divided into 4 groups, Leading Vowels (LV), Following Vowels (FV), Below Vowels (BV) and Above Vowels (AV). There are 4 tonemarks whose position is above a consonant. Diacritics are divided into 2 groups, Above Diacritics (AD) and Below Diacritics (BD).

Libthai has defined 4 levels for the position of a character.

- Below level: a character is placed below the consonant. th_chlevel() will return the value -1 for these characters.

- Base level: this includes consonants, FV and LV. A character is placed on baseline. th_chlevel() will return the value 0 for these characters.

- Above level: a character is placed just above the consonant. th_chlevel() will return the value 1 for these characters.

- Top level: this includes tone marks and diacritics. For plain character cell rendering, it is safe to put these characters at top-most level. However, some rendering engines may lower them down on absence of character at Above level, for typographical quality. th_chlevel() will return the value 2 for these characters.

There is an extra level value 3 for certain characters which are usually classified as characters at Above level, but are also allowed to be placed at Top level for some rare cases. Two characters fall in this category, namely MAITAIKHU and NIKHAHIT.

MAITAIKHU can be placed at Top level when writing some minority languages such as Kuy, to shorten some syllables with compound vowels, such as Sara Ia and Sara Uea. NIKHAHIT can be placed at Top level in Pali/Sanskrit words, to represent -ng final sound above SARA I.

The following figure illustrates a Thai word and characters' level.

    --------------------------- Top(2)
    ------*-------------------- Top(2)
    ------*-------------------- Top(2)
    ---------------------------
    --------------------------- Above(1)
    ------*---------------*---- Above(1)
    ---****---------------*---- Above(1)
    --------------------------- Above(1)
    ---------------------------
    --------------------------- Base(0)
    --*---*----***-----*--*---- Base(0)
    -*-*-*-*--*---*---*-*-*---- Base(0)
    --**-*-*------*---**--*---- Base(0)
    ---**--*---*--*---*---*---- Base(0)
    ---**--*--*-*-*----*--*---- Base(0)
    ---*---*--**--*---*---*---- Base(0)
    ---*---*--*---*---*---*---- Base(0)
    ---*---*--*****---*****---- Base(0)
    --------------------------- Baseline
    --------------------------- Below(-1)
    -------------------**-*---- Below(-1)
    --------------------***---- Below(-1)
    --------------------------- Below(-1)

A character placed at below, above or top level is also called dead character. It is usually combined with a consonant, after a dead character is typed, the cursor will not be advanced to the next display cell. BV, BD, TONE, AD and AV are classified as dead character.

## Function Documentation

## th_chlevel()

int th_chlevel | ( | thchar_t | c | ) |

extern

Position for rendering:

- 3 = above/top
- 2 = top
- 1 = above
- 0 = base
- -1 = below

## th_istis()

int th_istis | ( | thchar_t | c | ) |

extern

Is the character a valid TIS-620 code?

TIS-620 here means US-ASCII plus TIS-620 extension. Character codes in CR area (0x80-0x9f), non-breaking space (0xa0), code gap range (0xdb-0xde and 0xfc-0xff) are excluded.