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Re: reflow and PDFs

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From: Steve Green
Date: May 10, 2022 11:58PM

In terms of WCAG conformance, there is an exemption for data tables, so it is ok if there are both horizontal and vertical scrollbars. My (possibly incorrect) recollection is that VIP PDF Reader allows users to freeze rows or columns so they are always visible when scrolling the rest of the table.

VIP PDF Reader should also linearise the 2-column content into a single column even if Adobe Reader doesn't. However, it should do unless the 2-column layout has been created using tables or if the pages contain other content that prevents them from reflowing, such as images that have Alternate Text.

Have you investigated why the 2-column pages do not reflow? I'd be happy to take a look if you want to send me the document.

Steve Green
Managing Director
Test Partners Ltd


-----Original Message-----
From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of Duff Johnson
Sent: 10 May 2022 21:14
To: WebAIM Discussion List < <EMAIL REMOVED> >
Subject: Re: [WebAIM] reflow and PDFs

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.