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Re: Does PDF.JS render acccessible PDF experience?

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From: Philip Kiff
Date: Jun 19, 2024 9:09AM

Ha! Your mileage definitely will vary if you try to "edit" a PDF using
Firefox!

I wish Mozilla wouldn't even use the word "edit" in their marketing
materials since it's not really an editor. You're not really editing the
PDF file, so much as adding annotations on top of it, which is why they
can end up in the comments. Having said that, I tested a version of it a
few months ago and it did allow an image to be added (to the top layer
of the page) and it did allow the alternative text to be passed through
to a screen reader, and it inserted the figure tag at the end of the tag
tree for that page. I'm surprised it works at all, given the complexity
of the PDF file structure, and I'm interested to see how/if it continues
to develop.

Thanks for the additional insight into screen reader experience and
awareness. The tendency of browsers to take over PDF rendering has been
frustrating for all users, I think, and it has created new challenges to
achieving an accessible PDF experience. So many different rendering
experiences and different tag and form support.

Phil.

On 2024-06-19 10:30 a.m., Steve Green wrote:
> It's funny you should mention editing PDFs in Firefox, because Mozilla sent out an email this morning with the subject line "All you need to edit your PDFs". It talks about how you can use Firefox to add text and "you can add images with alt text for accessibility".
>
> I upgraded to the latest version of Firefox and tried it, and it's nothing short of disastrous. The fact that the "Try it now" and "Read more" buttons in the email don't work makes me wonder if it's a draft that they sent out by accident.
>
> I edited a PDF we had already made accessible and found the following:
>
> • Editing in Firefox removed all the tags.
> • It added all the new content in the Comments panel.
> • You can't set the size of a text frame and the text doesn't wrap, so it flows off screen as you type. However, when you save the document, the text frame gets moved to the extreme left and the font size gets reduced to (almost) fit the page width.
> • When you add an image, you are prompted to add Alternate Text. However, as far as I can tell, you never see it again – it's not in the Properties or anywhere else. NVDA can't even find any images in the document.
>
> That said, Firefox is by far the best browser for reading PDFs with a screen reader because it recognises all the tags (as far as I can tell). By contrast, Chrome and Edge are terrible. They ignore the Tags panel and do not expose any semantics at all. They guess what the headings are, apparently based on font size, but every heading is level 2.
>
> I am on an email forum for screen reader users, and there is absolutely no awareness of the level of accessibility support provided by different PDF readers. The topic comes up pretty much every week, and it's clear that people just use whatever the default reader turns out to be, and it's almost always a browser because they do everything they can to hijack the PDF file association. Almost no one makes a conscious choice to use a particular application. Worse still, there are all sorts of old wives’ tales about which reader application is best, almost all of which are wrong.
>
> Steve Green
> Managing Director
> Test Partners Ltd

On 2024-06-19 9:56 a.m., Philip Kiff wrote:
> I think Malthe is right that pdf.js generally tries to support tagged
> PDF.
>
> My understanding is that the Mozilla team have been actively working
> on improving that support over the past year or two. For example, I
> know that last year they worked on trying to maintain the tag order
> and structures after you "edit" (more properly annotate) a PDF through
> the Firefox browser. And their current issue queue includes a variety
> of issues that relate to proper rendering of PDF features required for
> accessible PDFs - for example, proper processing of merged table
> header cells in tables with more than one row header
> (https://github.com/mozilla/pdf.js/issues/18090).
>
> The level of tag support in pdf.js is an active, moving target. But my
> impression is that folks who use screen readers still usually prefer
> to open PDFs in external PDF reader software?
>
> It would be interesting to see someone do a full comparison of the
> level of accessibility support provided by Firefox vs Chrome vs Acrobat.
>
> Phil.
>
> Philip Kiff
> D4K Communications
>
> On 2024-06-19 5:15 a.m., Malthe Jepsen wrote:
>> HI
>> According to this Bugzilla page, pdf.js does indeed support tagged
>> PDF. It's the default viewer in Firefox, and after a cursory
>> inspection of a tagged PDF in Firefox with a screen reader, it seems
>> to render well.
>> https://bugzilla.mozilla.org/show_bug.cgi?id†1157
>>
>> Best
>> Malthe
>>> On 18 Jun 2024, at 20.27, Duff Johnson< <EMAIL REMOVED> >  wrote:
>>>
>>>
>>>> On Jun 18, 2024, at 14:10, Jon Metz< <EMAIL REMOVED> >  wrote:
>>>>
>>>> Well, I don't know if it's for security reasons. I just assumed
>>>> "security" was why Adobe limits access to the structure in their
>>>> Reader app.
>>> So far as I know Adobe doesn't limit access to the structure in any
>>> way…
>>>
>>> Duff.
>>>
>>>>