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https://issues.apache.org/jira/browse/PDFBOX-4189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16438540#comment-16438540
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John Hewson edited comment on PDFBOX-4189 at 4/15/18 12:11 AM:
---------------------------------------------------------------

Hi guys, this is a really welcome contribution, thank you. With regards to 
PDFont#encode(String text) being non-final I can add some insight as I was the 
original designer of our current PDFont#encode mechanism.

Basically, the PDFont classes are designed to represent fonts identically to 
how they are represented when embedded in PDF files. So there's no support for 
OpenType, by design. A Type0 font knows nothing about OpenType.

So how can we use OpenType in PDFBox? The answer is that we do it one layer of 
abstraction up, during text _layout_ instead of text _encoding_*_._* So you 
want to put your glyph substitution code inside PDPageContentStream#showText, 
actually you want 
[PDPageContentStream#showTextInternal|https://github.com/apache/pdfbox/blob/7e721643c0b1fca9fdc349f78431f36e68abc097/pdfbox/src/main/java/org/apache/pdfbox/contentstream/PDAbstractContentStream.java#L256].

That way PDFont#encode(String text) can stay non-final :)


was (Author: jahewson):
Hi guys, this is a really welcome contribution, thank you. With regards to 
PDFont#encode(String text) being non-final I can add some insight as I was the 
original designer of our current PDFont#encode mechanism.

Basically, the PDFont classes are designed to represent fonts identically to 
how they are represented when embedded in PDF files. So there's no support for 
OpenType, by design. A Type0 font knows nothing about OpenType (by design).

So how can we use OpenType in PDFBox? The answer is that we do it one layer of 
abstraction up, during text _layout_ instead of text _encoding_*_._* So you 
want to put your glyph substitution code inside PDPageContentStream#showText, 
actually you want 
[PDPageContentStream#showTextInternal|https://github.com/apache/pdfbox/blob/7e721643c0b1fca9fdc349f78431f36e68abc097/pdfbox/src/main/java/org/apache/pdfbox/contentstream/PDAbstractContentStream.java#L256].

That way PDFont#encode(String text) can stay non-final :)

> Enable rendering of Indian languages, by reading and utilizing the GSUB table
> -----------------------------------------------------------------------------
>
>                 Key: PDFBOX-4189
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-4189
>             Project: PDFBox
>          Issue Type: New Feature
>          Components: FontBox, PDModel
>            Reporter: Palash Ray
>            Priority: Major
>         Attachments: Bengali-text-after.pdf, Bengali-text-before.pdf
>
>   Original Estimate: 336h
>  Remaining Estimate: 336h
>
> Implemented proper rendering of Indian languages, which need extensive Glyph 
> substitution. The GSUB table has been read and used effectively to replace 
> some compound words with their respective Glyphs. All tests are passing. I 
> have tested this for the Bengali font. Please review these changes and let me 
> know if it makes sense to incorporate these.



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