I just implement to put the render of Khmer Unicode in iText 5.5.4-SNAPSHOT and try, I could produce the PDF with the right display as following image.

iText is a core pdf writer in most of the opensource library for outputting report or rendering text but unfortunately, it’s not working with Khmer Unicode as I stated previously in my post.
itext-with-khmer-render-start

 

It’s just only the initial work and not yet done and sure that it’s fully working fine yet.

Remark: I have read: http://www.redlab.be/blog/2011/developer-guide/

And I have tried:

itext/src/main/java/com/itextpdf/text/pdf/TrueTypeFont.java
itext/src/main/java/com/itextpdf/text/pdf/languages/khmer
itext/src/main/java/com/itextpdf/text/pdf/languages/khmer/UnicodeRender.java
itext/src/main/java/com/itextpdf/text/pdf/languages/khmer/UnicodeUtil.java
itext/src/main/java/com/itextpdf/text/pdf/languages/KhmerLigaturizer.java

Update:

There won’t be an easy task to integrate the latest iText (5.x) version to some opensource product such as JasperReport to test Khmer render since they are still using very old version 2.1.7.

One more remark on iText product about its revolution since version 2.1.7, 4.2.0 to 5.x:

 

Source Code