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Re: reflow and PDFs

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From: Duff Johnson
Date: May 10, 2022 2:13PM

Hi Alan,

> I am working on a PDF with tables that have 10 columns, At zoom above 200%
> you have to do horizontal scrolling and "lose" the left most row header
> cell.

Please allow me to rephrase your statement from a file format specification point of view…

“The application fails to account for tables with many (or wide) columns at high zoom levels."

> Apart from the tables, the document is mostly 2 column layout, and
> this will not stack into 1 column, either, so you have to constantly scroll
> to read, then scroll back and down, etc.

Sounds like a pain. To support such tables the application needs to be able to represent the TH cells for the currently-displayed TD cells regardless of any given location in the table.

> These documents are legacy, and there is no way to redesign them in any
> significant way.

Nor should that be necessary, if the application would just do the right thing.

> Question: is the above a serious failure or just a nuisance?

It's no statement about the file per se, as the file may well include a correctly-tagged table. It's a problem with the zooming software, and should be reported to the developer as a necessary enhancement required in order to credibly support larger tables under high magnification.

> I suppose what I am asking relates to the question: what are the PDF/UA
> reflow requirements, as opposed to best requirements?

There are no PDF/UA requirements for reflow at all. PDF/UA specifies that the content be correctly tagged. It leaves the implementation of the tagging in a viewer (of which reflow is one such) to the viewer software developer.

I hope this helps.

Duff.