PDFlib 8 Windows COM/.NET Tutorial

will prevent them from being replaced by a ligature even if ligatures are enabled in the
features option. For example, the following sequence will not create any f+i ligature:
Schilf‌insel
Script- and language-specific OpenType layout features. OpenType features may apply
in all situations, or can be implemented for a particular script or even a particular
script and language combination. For this reason the script and language text options
can optionally be supplied along with the features option. They will have a noticeable effect
only if the feature is implement in a script- or language-specific manner in the font.
As an example, the ligature for the f and i glyphs is not available in some fonts if the
Turkish language is selected (since the ligated form of i could be confused with the dotless
i which is very common in Turkish). Using such a font the following Textflow option
will create a ligature since no script/language is specified:
fi
However, the following Textflow option list will not create any ligature due to the Turkish
language option:
fi
The locl feature explicitly selects language-specific character forms. The liga feature contains
language-specific ligatures. Some examples for language-specific features:
Variant character for Serbian:
б
Variant figures for Urdu:
٢٣٤٥
See Section 6.4.2, »Script and Language«, page 166, for supported script and language
keywords.
Combining OpenType features and shaping. Shaping for complex scripts (see Section
6.4, »Complex Script Output«, page 164) heavily relies on OpenType font features which
will be selected automatically. However, for some fonts it may make sense to combine
OpenType features selected automatically for shaping with OpenType features which
have been selected by the client application. PDFlib will first apply user-selected Open-
Type features (option features) before applying shaping-related features automatically
(options shaping, script and language).
Querying OpenType features programmatically. You can query OpenType features in
a font programmatically with info_font( ). The following statement retrieves a spaceseparated
list with all OpenType features which are available in the font and are supported
by PDFlib:
result = (int) p.info_font(font, "featurelist", "");
if (result != -1)
{
/* retrieve string containing space-separated feature list */
featurelist = p.get_parameter("string", result);
}
else
6.3 OpenType Layout Features 161