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Frank Jonen

A4 is not A4 in PDF Export

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Encountered a bug with PDF export.


The exported document has a size of 21,01 × 29,71 cm instead of 21 x 29,7 cm. This kicks off the scaling trigger in Preview's printing dialogue with a default of 96% which throws off all alignment with any pre-defined labels. Actual A4 documents don't prompt it. And yes I've set the scaling value of Preview's defaults to 'false'. That only works when the document is A4, though.


I haven't had the time to test for all paper sizes but if it's a PDFlib bug it probably affects all.



Fortunately it's easy to reproduce:

  1. Create a document in A4
  2. Check document sizes, they're correct
  3. Put some stuff on the page
  4. Export to PDF, leave everything as default
  5. Open file in Preview, sizes are incorrect now


Also while I was writing this, Affinity Designer crashed in the background, that happens a lot when it's not a foreground app.

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No I did not. I check with apps that I actually use.


Did you check the page size in Acrobat?





The values I get from the PDF itself are correct with 595.276 × 841.89 pt and all boxes set to: 0.00   0.00   595.28   841.89.


Could be that this sudden error has more to do with a macOS update than Affinity. Preview.app doesn't round the stored point values as heavily as before and uses the system's SI units to send to the printer driver. :unsure:   Still weird since that would make it 210.0001444 mm, not 210.0 mm.


If you have a macOS version above Yosemite, could someone check if that's still the case? I used to be able to print PDFs made in Affinity without getting a scaling prompt. 


Anyone able to recreate the problem with Preview.app wanting to scale AD/AP generated output?

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I managed to test it on Sierra with a PDF and Preview there shows the correct values, no rounding errors. The system doesn't yet have a printer set up so I couldn't test with an actual AD PDF. But I remembered something which indicates why my own PDFs print without forced scaling. I went through my source code and yup, I set PrintScaling to 'None' in the catalog section of the viewer settings. Preview seems to respect that.


That's why AD PDFs print scaled down and my others don't.


Not a bug, just different ways of setting up a PDF.

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