This is probably rather difficult but it would be very useful if you could output an ePub which already included the bizarre JSON-based hyperlinks with area magnification required for fixed layout Kindle format. Kindlegen does a great job of converting ePubs apart from the links.
Anyway, great job.
thank you for the suggestion.
I assume you are talking about the Amazon Kindle Publishing Guidelines 4.2.2 - Using Region Magnification.
That is an interesting feature, and a good suggestion. The main difficulty, is that most input files (such as PDF) don’t contain much structure, (in PDF there is no such thing as a sentence or paragraph) and therefore, the magnified content that would appear on a double tap would often just be a single character!
Fortunately we are working on some advanced structure recognition, and text simplification technologies, see posts below. So perhaps we will integrate the two together.