Annotations in HTML and TXT files

Hey Guys,

I need to know, how can I annotate highlights in TXT & HTML files, I learned to annotate in PDF files by using co-ordinates, how do we track annotations in HTML or TXT files? by co-ordinates? Do we convert HTML/TXT files to PDF and then use PDFtron on them or what?
Please help me out here!!

Hello, I’m Ron, an automated tech support bot :robot:

While you wait for one of our customer support representatives to get back to you, please check out some of these documentation pages:


PDF ISO format specifies annotations and how they are positioned and sized. This is unambiguous since PDF pages are fixed layout.

HTML and TXT files are reflowable, they do not have a fixed position or scale.

Generally with our SDK you convert files to PDF and then annotate them.

Though specifically for HTML there is annotation options not necessarily tied to a PDF file.

The best way for me to help you is if you could elaborate on:
what you are doing now?
what you are trying to accomplish?
and why the above is important for you?

1 Like

Hi Ryan,

I’m developing a functionality where problem statement is,

  1. We will receive some coordinates in case of PDF files, xpath & offsets in case of Text & HTML files.
  2. We need to highlight these specific areas in all three PDF, HTML, & TXT files.

Well PDFtron helped in implementing this feature on PDFs, I was stuck because I couldn’t think of anything in case of TXT & HTML, but now I have finally managed to make a custom feature for HTML & TXT, so that’s it.

Thanks for your reply, I will update this conversation if I’ll get stuck on PDFs in future!