FontForge -- An Outline Font Editor

Quoting James Cloos <cloos@...>:

> ,----< from DejaVu Serif >
> | lookup ligaStandardLigatures {
> |   lookupflag 0;
> |     sub \f \f  by \uniFB00;
> |     sub \f \l  by \fl;
> |     sub \f \f \l  by \uniFB04;
> |     sub \uniFB00 \l  by \uniFB04;
> | } ligaStandardLigatures;
> `----
> 
> What I can't tell is whether anything can be done in the .sfd to
> optimize the lookups, putting longer RHSs ahead of shorter.
No. Because you don't need to. That should be done for you by fontforge as there
is no ambiguity involved. "ffl" should always be tried before "ff".

Do you have some reason to believe that there is an error?

On Mon, 2008-07-21 at 06:58, James Cloos wrote:
> ,----< from DejaVu Serif >
> | lookup ligaStandardLigatures {
> |   lookupflag 0;
> |     sub \f \f  by \uniFB00;
> |     sub \f \l  by \fl;
> |     sub \f \f \l  by \uniFB04;
> |     sub \uniFB00 \l  by \uniFB04;
> | } ligaStandardLigatures;
> `----
> 
> What I can't tell is whether anything can be done in the .sfd to
> optimize the lookups, putting longer RHSs ahead of shorter.
Here's the quote I was looking for:
http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html#5.d
A contiguous set of ligature rules does not need to be ordered in any
particular way by the font editor; the implementation software must do
the appropriate sorting.

>>>>> "George" == George Williams <gww@...> writes:

George> Here's the quote I was looking for:
George> http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html#5.d
George> A contiguous set of ligature rules does not need to be ordered
George> in any particular way by the font editor; the implementation
George> software must do the appropriate sorting.

Interesting.  The slides from:

http://blogs.adobe.com/typblography/atypi2006/slye_lisbon-05.pdf

around page 53-55 or so claim otherwise.  They state that you have to
have ffi before ff else ffi will be ignored.

I have no idea which reference is correct, but that talk discussed how
Adobe currently does their font design.

-JimC
-- 
James Cloos <cloos@...>         OpenPGP: 1024D/ED7DAEA6

On Mon, 2008-07-21 at 13:19, James Cloos wrote:
> I have no idea which reference is correct, but that talk discussed how
> Adobe currently does their font design.
The quote I provided is directly from Adobe's online documentation of
the feature file format.

I am not aware of any other source of information on this format.

The quotation is very clear, the example given even clearer, both
directly address the issue. At one point someone at Adobe put some
thought into the matter and came up with that answer, and documented it.

If there is a problem it is up to Adobe to fix it.
  If their software does not conform to their specification that is
     their problem.
  If they have changed the specification internally they must do so
     externally as well.

>>>>> "George" == George Williams <gww@...> writes:

George> The quote I provided is directly from Adobe's online
George> documentation of the feature file format.

I know that.  That is why I said that I don't know which is correct.

George> I am not aware of any other source of information on this format.

The pdf I quoted was slides from a presentation about how to create
OpenType fonts.  It does say that the order in the feature file is
preserved in the generated font when using their tools.

George> The quotation is very clear,

No debate there.  Just two Adobe publications which disagree.

I just checked DejaVu Serif in ttx, and it gives:

      <Lookup index="3">
        <LookupType value="4"/>
        <LookupFlag value="0"/>
        <!-- SubTableCount=1 -->
        <LigatureSubst index="0" Format="1">
          <LigatureSet glyph="f">
            <Ligature components="f,l" glyph="uniFB04"/>
            <Ligature components="l" glyph="fl"/>
            <Ligature components="f" glyph="uniFB00"/>
          </LigatureSet>
          <LigatureSet glyph="uniFB00">
            <Ligature components="l" glyph="uniFB04"/>
          </LigatureSet>
        </LigatureSubst>
      </Lookup>

so that suggests that ff does what I suggested when generating fonts,
just not when exporting feature files.

Which is all I really care about.  I'd rather use a script than export,
edit and import a feature file anyway.

It just happened that feature file were being discussed here at the same
time I followed a pointer to that pdf an was reading it, so I got
curious about what Deja's features looked like in adobe syntax.

I should've checked the exported font before posting......

-JimC
-- 
James Cloos <cloos@...>         OpenPGP: 1024D/ED7DAEA6

On Sun, 2008-07-20 at 23:35, kuoping wrote:
> The BitmapsAvail function of script dose not work.
Here is the fix.