我正在为Sgaw Karen开发字体，这种语言要求根据上下文对字符（和连字）进行整形。我的字体工作得很好，但是，我希望在Mac上添加一个AAT MORX表以获得更好的支持。
但是，我很难理解AAT字体功能的语法。特别是上下文类型。我已经阅读了Apple参考和教程文档，并看到了here列出的示例。
基本上，我有两个字符，假设X和Y需要替换为连字，如果后跟一组特定字符，比如说N和M.对于FontLab Studio中的OpenType特性，我只想说：
sub X' Y' [N M] by X_Y.alt;
它工作得很漂亮。我如何在AAT中做同样的事情？
这是我的完整OT代码：
feature clig {
script mymr;
@needSpaceOnTop = [uni102B uni1032 uni102D uni102E];
sub uni1000' uni103C' @needSpaceOnTop by uni1000_uni103C.alt;
sub uni1003' uni103C' @needSpaceOnTop by uni1003_uni103C.alt;
sub uni1006' uni103C' @needSpaceOnTop by uni1006_uni103C.alt;
sub uni1010' uni103C' @needSpaceOnTop by uni1010_uni103C.alt;
sub uni1011' uni103C' @needSpaceOnTop by uni1011_uni103C.alt;
sub uni1018' uni103C' @needSpaceOnTop by uni1018_uni103C.alt;
sub uni101C' uni103C' @needSpaceOnTop by uni101C_uni103C.alt;
sub uni101E' uni103C' @needSpaceOnTop by uni101E_uni103C.alt;
sub uni101F' uni103C' @needSpaceOnTop by uni101F_uni103C.alt;
sub uni1001' uni103C' @needSpaceOnTop by uni1001_uni103C.alt;
sub uni1002' uni103C' @needSpaceOnTop by uni1002_uni103C.alt;
sub uni100E' uni103C' @needSpaceOnTop by uni100E_uni103C.alt;
sub uni1004' uni103C' @needSpaceOnTop by uni1004_uni103C.alt;
sub uni1005' uni103C' @needSpaceOnTop by uni1005_uni103C.alt;
sub uni1007' uni103C' @needSpaceOnTop by uni1007_uni103C.alt;
sub uni1012' uni103C' @needSpaceOnTop by uni1012_uni103C.alt;
sub uni1015' uni103C' @needSpaceOnTop by uni1015_uni103C.alt;
sub uni1016' uni103C' @needSpaceOnTop by uni1016_uni103C.alt;
sub uni1019' uni103C' @needSpaceOnTop by uni1019_uni103C.alt;
sub uni101D' uni103C' @needSpaceOnTop by uni101D_uni103C.alt;
sub uni1065' uni103C' @needSpaceOnTop by uni1065_uni103C.alt;
} clig;
以下是OS X字体工具文档的上下文示例：
------------------------------------------------------------------
// Turn medial s into long s
------------------------------------------------------------------
Type Contextual
Name Smart Swashes
Namecode 8
Setting Medial Long-s
Settingcode 8
Default no
Orientation H
Forward yes
Exclusive no
Ess s
Lower a b c d e f g h i j k l m n o p q r t u v w x y z
EOT OOB DEL EOL Ess Lower
StartText 1 1 1 1 2 1
StartLine 1 1 1 1 2 1
SawS 1 1 1 1 3 4
SawSS 1 1 1 1 3 4
GoTo Mark? Advance? SubstMark SubstCurrent
1 StartText no yes none none
2 SawS yes yes none none
3 SawSS yes yes ToLongS none
4 StartText no yes ToLongS none
ToLongS
s slong
答案 0 :(得分：2)
好的，我已经把它弄清楚了。 AAT不直接支持上下文连字。但你可以通过使用两个传递来实现它，如下：
如果后跟N或M，则将X Y更改为X_Y：
//====================================================
// Step 1: change Y to an arbitrary high glyph number
// if it is preceded by X and followed by N or M
//====================================================
Type Contextual
Name NULL
Namecode 7
Setting NULL
Settingcode 0
Default yes
Orientation HV
Forward yes
Exclusive no
// Define some classes
X X
Y Y
NM N M
// Define what action to take for state/action
EOT OOB DEL EOL X Y NM
StartText 1 1 1 1 2 1 1
StartLine 1 1 1 1 2 1 1
SawX 1 1 1 1 1 3 1
SawY 1 1 1 1 1 1 4
// The state machine starts off in the StartText or StartLine state.
// If it sees an X in one of those states, it changes to the SawX
// state. If it's in the SawX state and sees a Y, then it changes to
// the SawY state and marks that character (the Y) for possible
// future processing. Then if it sees an N or M in the SawY state,
// it runs the DoSub on the marked Y, and returns to the StartText state.
// Actions - the Goto column tells what state to take for
// the next round.
GoTo Mark? Advance? SubstMark SubstCurrent
1 StartText no yes none none
2 SawX no yes none none
3 SawY yes yes none none
4 StartText no yes DoSub none
// Subs Y by 5999
DoSub
Y 5999
//====================================================
// Step 2: Change the X 5999 to X_Y
//====================================================
Type LigatureList
Name NULL
Namecode 7
Setting NULL
Settingcode 0
Default yes
Orientation HV
Forward yes
Exclusive no
// Replace X 5999 by X_Y
List
X_Y X 5999
当然，要使其正常工作，5999必须不是以前存在的字形ID。