WebAIM - Web Accessibility In Mind

E-mail List Archives

Re: Disappearing PDF content

for

From: Duff Johnson
Date: Jul 28, 2014 4:05PM

Hi Michelangelo,

We professionals call this the “z-order problem”, but it’s known to most users as “<howl of pain> I hate fixing this! !@#%^^&* Acrobat!?!? </howl of pain>"

You asked “is there a way to avoid it” - there are a couple of key mitigation strategies.

You said that you are using Acrobat to tag, so this is remedial. Bevi’s absolutely right - ideally this should be done when the file is authored.. but that’s not your case, it seems.

With Acrobat as presently designed, the only way to conclusively avoid the problem you are encountering is to be sure that you only select the items you want selected prior to setting a tag. This isn’t always easy. In particular, this usually means avoiding any paths and images when you are trying to select text, and conversely, avoiding all unassociated objects when you attempt to select a bunch of paths and text that you might want to tag as a single <Figure> (for example, a diagram).

What’s going on is that Acrobat just assumes that you want to tag all the objects you’ve got selected - whatever they are. It’s not smart enough to say (if applications could talk): “Hey, my user selected a big block of text that looks like a paragraph, and he going for a <P> tag. I should probably ignore the fact that he also selected a large image when he zoned that paragraph, at least by default."

The current-generation “brains” aren’t super-awesome at the big-picture questions like that.

Pay careful attention to the items you are selecting. You can use shift-click to add content to your current selection, or option-click (on a Mac) to zone content for removal from the selection. Note the cursor changes to indicate the current mode. These are important tools for this purpose. They aren’t perfectly implemented… and PDF files can be very hairy as you now know, but they really help.

Also, be sure to save your work at frequent intervals - and hopefully, right before you make a move that screws up the content’s z-order. You can’t really undo from content-reordering very frequently, the content ordering is screwed up in several places, or putting it back into the right order is daunting (for example, with lots of objects on the page).

It’s much easier and safer to dump your current file and go back to a PDF from just before you made the move which screwed up your z-order. V

Save yourself the suffering, and dump that file!, revert to your last save! In practice, when I’ve do this hand-work I’m saving the file every 10 minutes or so.

Go in peace with your file, my brother.

Duff.


On Jul 28, 2014, at 3:10 PM, Iaffaldano, Michelangelo < <EMAIL REMOVED> > wrote:

> Recently I have had to use Acrobat to make a PDF newsletter more accessible. The document had been created in Microsoft Publisher and its reading order was especially bad. One problem I encountered is that sometimes, when moving a tag to its appropriate place in the reading order pane - for example, placing a heading above the pertinent paragraph - the corresponding text would become invisible in the document viewer. Has anyone encountered this and is there a way to avoid it?
>
> Michelangelo
>
> > >