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_ASeidel_
Known Participant
May 14, 2003
Question

feature ss01 overwrites feature liga

  • May 14, 2003
  • 3 replies
  • 989 views
Maybe its a bug of InDesign 2.02 Win. I use a ss01 feature to switch T
T.alt by T.alt2.

But an existing ligature feature T.alt2 T.alt2 by T_T will not be
performed by InDesign if this ss01 feature is present in the font data.

Think the ss01 feature is not really supported by InDesign 2.02. It is a
bug of InDesign?

Think the liga feature should have priority over any ss0x feature.


Andreas
This topic has been closed for replies.

3 replies

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_J_Hudson_
Participant
May 14, 2003
The <locl> feature should be first, since this is particular to Language System and should set up the glyphs for all following features. Think of the <locl> feature as substituting new default forms for specific Language Systems, with all subsequent features treating the <locl> substitutions as if they were the default glyphs. [The Windows text/OT engine, Uniscribe, forces ordering of some featues, and always processes <ccmp> and <locl> as the first two features.]<br /><br />Putting <ss01> etc. immediately after <locl> is a good idea, although they could also go after <aalt> without any problems.<br /><br />The <kern> feature might as well go last, since GPOS features are always processed after GSUB features.
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_Adam_Twardoch_
Known Participant
May 14, 2003
Andreas,
I don't think any feature should have priority over any other feature. The lookups in OpenType fonts are applied in the sequence according to the lookup sequence. I think it's a good mechanism.
Adam
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_J_Hudson_
Participant
May 14, 2003
How are your lookups ordered? In order to be reactive to output from <ss01>, your <liga> feature lookups need to be ordered after <ss01>. Using the FDK or FontLab, you can only order complete features, not individual lookups, so you either need to put the <liga> feature after the <ss01> feature or include lookups in the latter to maintain ligatures, e.g. putting a lookup in the <ss01> feature that precedes lookups involving T and that maps T_T to itself. Obviously reordering the features is more efficient.
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_ASeidel_Author
Known Participant
May 14, 2003
J Hudson wrote:<br />> <br />> How are your lookups ordered? In order to be reactive to output from <ss01>, your <liga> feature lookups need to be ordered after <ss01>. Using the FDK or FontLab, you can only order complete features, not individual lookups, so you either need to put the <liga> feature after the <ss01> feature or include lookups in the latter to maintain ligatures, e.g. putting a lookup in the <ss01> feature that precedes lookups involving T and that maps T_T to itself. Obviously reordering the features is more<br /><br /><br />Hello John,<br /><br />thank you for your comment. I reordered the ss0x feature and now it<br />works. It`s best to place ss0x on top after the kerning feature? Because<br />it overwrites my dlig hlig & calt features too.<br /><br />my the feature order is now:<br /><br />kern<br />ss01 - ss10<br />aalt<br />locl<br />onum<br />pnum<br />tnum<br />numr<br />dnom<br />frac<br />liga<br />dlig<br />hlig<br />salt<br />#ss01 - ss10 <br />liga<br />hist<br />calt<br />ordn<br />ornm<br /><br />ps. I use the FDK only - it an FDK group ;-)<br /><br /><br />Andreas
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