Sub-page transition effects should only affect the OCG they point to

[jpakkane]

Suppose you want to create a PDF presentation with bullet points that appear one by one like this:

A heading

- first bullet
- second bullet
- third bullet

If you specify a transition like fly, you'd expect the "new" content to fly in while the rest of the slide remains unchanged.

AFAIK the only PDF viewer that displays sub-page transitions is is Acrobat Reader and it does not behave like this. Instead what it does is to render the whole page on a different "slide" and then fly that in over the old one. Basically the behavior is identical to having a full page transition.

Indeed this seems to be allowed by the standard, which only says this in 12.4.4.2: "Transition effects, similar to the page transitions described earlier, may be specified as transition actions that are part of the NA or PA sequence; see 12.6.4.15, "Transition actions"."

This should be amended to say something like "the PDF processor should, when feasible, apply this transition effect only to the optional content group(s) that are part of the action in the navigation node".

[jpakkane]

I looked into this a bit more and apparently it is possible to do this, but only with the fly transition type. Or at least that is what Acrobat does. I currently only have the 1.7 spec and the only place that mentions this is in the transition type table that says "Changes are flown out or in". Note that subpage transitions (which this applies to) are only discussed after the table.

This should be supported in (some) other transition types as well. And if not, then at the very least the textual description could be a bit more direct on the interplay between subpage transitions and transition types.