On 28/10/15 04:03, William Bader wrote: > > >> To: [email protected]; [email protected] >> From: [email protected] >> Date: Tue, 27 Oct 2015 23:08:54 +1030 >> Subject: Re: [poppler] Printing of certain PDF files does not work > with "fit-to-page" because of wrong BoundingBox values in the PostScript >> >> On 25/10/15 21:08, Stefan Brandner wrote: >> > I want to summarize how the problem appears when printing the file >> > Dirichlet.pdf with okular. >> > Find the file at: https://bugzilla.opensuse.org/attachment.cgi?id=616147 >> > >> > 1. with OpenSuse 13.1 and okular 4.11.2 the CUPS command was without the >> > fit-to-page option >> > following commands are executed: >> > pdftops Dirichlet.pdf >> > lpr Dirichlet.ps >> > The file was printed unscaled but centered and the printout was useful. >> > >> > 2. with the actual OpenSuse 13.2 and okular 4.14.9 the CUPS command is >> > now with fit-to-page and then the file is shifted to the right with half >> > of the text cut >> > this can be reproduced with following commands: >> > pdftops Dirichlet.pdf >> > lpr -o fit-to-page Dirichlet.ps >> > This does not work since the BoundingBox values are incorrect. >> > See explanation at CUPS documentation: >> > http://www.cups.org/documentation.php/options.html >> >> I'm not sure which application is enabling the fit-to-page or why it >> changed. The fit to page would be better performed in pdftops which >> already has this capability. The problem with performing a fit-to-page >> based on the PS output is the Adobe Document Structuring Conventions >> define the BoundingBox to be the smallest box that encloses all marks on >> the page. >> >> A PS file with correctly calculated PageBoundingBox comments is likely >> have a different bounding box on each page depending on the content. If >> fit-to-page is applied based on the bounding box, each page will have a >> different scale factor applied. A blank page with just a page number at >> the bottom will be scaled up to fit the page number to the entire page. >> This is probably not what you want. >> >> The fit-to-page feature relies on the fact that a lot of applications >> just set the bounding box to the page size since computing the ink >> extents of all marks on the page is not trivial. >> >> If a future version of poppler tightened up the PageBoundingBox to make >> it more correct you may find this workflow which relies on an incorrect >> interpretation of the BoundingBox comment may no longer work for you. > > > The problem is that the pdftops -paper option creates a > PageBoundingBoxes that can point to empty space instead of to the image. > It is not that the PageBoundingBox is too large but that it is > completely wrong.
Yes, I understand the current bounding box is bogus and the patch fixes it to ensure the bounding box does not truncate any of the page content. That alone is a good enough reason to apply the patch. But my point is the new bounding box still does not comply with the DSC spec. A future version of poppler may make the bounding box "more correct" and as a result the CUPS fit-to-page feature will not work the same as it does with the current patch. > pdftops always writes the PageBoundingBox as 0,0 to > the width,height of the image, but if pdftops is run with -paper, it > shifts the image up and to the right to center it on the page but it > does not make a corresponding shift to the PageBoundingBox. > > > The issue is not setting the PageBoundingBox to cover the smallest > rectangle necessary to cover the marks on the page. An application that > creates a document where a page has only a page number or a "this page > intentionally left blank" notice will usually still write a normal > page-sized crop box. But if you have a document that was created for a > small paper size like a note card and then you want to print it on A4, > if you use pdftops -paper A4, pdftops will correctly center the note > card pages on the A4 paper (and enlarge them if you use -expand), but it > will leave the PageBoundingBox comments as a note card sized rectangle > at the lower left corner, so viewers or applications that read the > PageBoundingBox will look at empty space. > > > Regards, William > > > _______________________________________________ poppler mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/poppler
