Developing OpenType Fonts for Bangla Script [ Microsoft Volt & Fontlab ]

 Character reordering Classes for Bangla:
Table 2
Characters                                                                               Reorder Class

U+09B0 - র ,  U+09F0 - ৰ  (reph)                                              AfterSubscript


U+09BF- ি , U+09C7-ে, U+09C8-ৈ                                       BeforeHalf


U+09C1- ু , U+09C2-ূ,  U+09C3-ৃ,                                         AfterSubscript
U+09C4-U+09E2-U+09E3-ৡ, U+09F5-ৣ


U+09BE-া, U+09C0-ী, U+09D7-                                         AfterPostscript


U+0981-  ঁ,                                                                                 AfterPostscript




Invalid Combining Marks


U+200C    ‌   [  ZWNJ ]            Zero width non-joiner

 

U+200D      ‍ [ ZWJ ]              Zero width joiner 


U+25CC                                Dotted Circle


OpenType features used for Bengali scripts, applied in the following order:

FeatureFeature functionLayout operation

Localized forms:

locl

Localization form substitution

GSUB

Basic shaping forms:

nukt

Nukta form substitution

GSUB

akhn

Akhand ligature substitution

GSUB

rphf

Reph form substitution

GSUB

blwf

Below-base form substitution

GSUB

half

Half-form substitution

GSUB

pstf

Post-base form substitution

GSUB

vatu

Vattu variants

GSUB

cjct

Conjunct form substitution

GSUB

Mandatory presentation forms:

init

Initial form

GSUB

pres

Pre-base substitution

GSUB

abvs

Above-base substitution

GSUB

blws

Below-base substitution

GSUB

psts

Post-base substitution

GSUB

haln

Halant form substitution

GSUB

Discretionary presentation forms:

calt

Contextual alternates

GSUB

Positioning features:

kern

Kerning

GPOS

dist

Distances

GPOS

abvm

Above-base mark positioning

GPOS

blwm

Below-base mark positioning

GPOS


[GSUB = glyph substitution, GPOS = glyph positioning]

Localized forms

Feature Tag: "locl" - OpenType language system tags



Nukta form substitution

Feature Tag:   "nukt"   

Microsoft Volt:  


Fontlab 5/6:-

feature nukt {

# Nukta Forms

sub u09AC u09BC by u09B0;

sub u09A1 u09BC by u09DC;

sub u09A2 u09BC by u09DD;

sub u09AF u09BC by u09DF;

#> feature

#< feature

} nukt;



Akhand

Feature Tag: "akhn"



Fontlab 5/6:-

feature akhn {

# Akhand


sub u0995 u09CD u09B7 by u0995_u09CD_u09B7;

sub u099C u09CD u099E by u099C_u09CD_u099E;


#> feature

#< feature

} akhn;







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