Tilman Hausherr created PDFBOX-5700:
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Summary: Ligature substitution cannot be switched off
Key: PDFBOX-5700
URL: https://issues.apache.org/jira/browse/PDFBOX-5700
Project: PDFBox
Issue Type: Bug
Components: FontBox
Affects Versions: 3.0.0 PDFBox
Reporter: Tilman Hausherr
It is not possible to switch off the ligature substitution if one doesn't
ligatures or if the ligatures are faulty, as mentioned in the linked SO
question.
The {{disableGsubFeature}} call works only for vertical fonts, which uses a
strategy that is completely different than ligatures or indian font
substitution.
How it works currently: PDAbstractContentStream uses GsubWorkerFactory to get a
GsubWorker. That one doesn't have access to the information whether
GsubFeatures are enabled or disabled. It doesn't even have access to a
TrueTypeFont object.
The simplest solution would be to enable or disable substitutions at the
PDType0Font level. A better solution would be to switch individual Gsub
features (FEATURES_IN_ORDER in the GSubworkers) on and off.
What's also unclear is if it should be on by default or off by default. Indian
substitutions should be on. European ligatures are nice, but not really
important. Then there are some "fun" features like "Swash" (swsh).
https://en.wikipedia.org/wiki/List_of_typographic_features
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