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

int th_chlevel ( thchar_t c )

Position for rendering:

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

int th_istis ( thchar_t c )

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.

Functions

Detailed Description

Function Documentation