Warn users about the PDF size limit and consequences

[holloway]

PDF 1.4 has a maximum page size that's enforced by Adobe Acrobat. If you open a large document in Adobe Acrobat 9.3.2 (Linux) then it will show a blank document and not report any error.

The feature/bug in Inkscape is that it says it's exporting PDF 1.4 but it doesn't warn/respect the limits of PDF 1.4. I suggest that a popup warning occurs when exporting PDF as PDF 1.4 if the document dimensions are too large.

To reproduce this make a page that's 6 metres by 3 metres, draw a big circle in it, and then export as PDF. Open the resulting file in Acrobat and see a blank document.

According to the PDF Reference 1.6 documentation:

"177. In PDF versions earlier than PDF 1.6, the size of the default user space
unit is fixed at 172 inch. In Acrobat viewers earlier than version 4.0, the
minimum allowed page size is 72 by 72 units in default user space (1 by 1
inch); the maximum is 3240 by 3240 units (45 by 45 inches). In Acrobat
versions 5.0 and later, the minimum allowed page size is 3 by 3 units (approximately
0.04 by 0.04 inch); the maximum is 14,400 by 14,400 units
(200 by 200 inches).
Beginning with PDF 1.6, the size of the default user space unit may be set
with the UserUnit entry of the page dictionary. Acrobat 7.0 supports a
maximum UserUnit value of 75,000, which gives a maximum page dimension
of 15,000,000 inches (14,400 * 75,000 * 172). The minimum
UserUnit value is 1.0 (the default)."

[knut (mr-knut)]

Using Inkscape 0.48.0 on Ubuntu 10.04 the "save as PDF" dialog offers the possibility to restrict to PDF Version 1.4 (actually there are no other choices) but the generated file starts with %PDF-1.5

It would also be nice to have command line parameters corresponding to the save dialog options.

[su_v (suv-lp)]

knut wrote:
> Using Inkscape 0.48.0 on Ubuntu 10.04 the "save as PDF" dialog offers
> the possibility to restrict to PDF Version 1.4 (actually there are no
> other choices) but the generated file starts with %PDF-1.5

That's tracked in Bug #664335 in Inkscape: “pdf export with cairo 1.10 defaults to version PDF-1.5”
<https://bugs.launchpad.net/inkscape/+bug/664335>
(As described in comment #9 there, Inkscape does not make any use of cairo's supported PDF-1.5 features for now).

[jazzynico (jazzynico)]

Since it's a PDF 1.4 and 1.5 format restriction, there's nothing we can do except warning the users that the exported files can't be read with Acrobat tools (note that it works correctly with Evince, and probably some other PDF readers).

Proposing to change the bug report to a wishlist report with "Warn users about the PDF size limit and consequences" as a title.

[su_v (suv-lp)]

Related: the risk of cairo crashing on PDF export of a drawing area of roughly 5'645 x 5'645 m probably could be mitigated by checking PDF export dimensions first, and prompting the user whether to proceed or not:
* Bug #1474884 “crash on save as PDF”
  https://bugs.launchpad.net/inkscape/+bug/1474884