to get crop box, bleed box, trim box and art box always fails

[Han Chipset]

I test many pdf files got on the net. To get the crop box, trim box, bleed box and art box, always fails, but for the media box and bounding box always succeeds. All related function protocols hereby are in file fpdf_tranformpage.h

If we cannot get the crop box, trim box, bleed box and art box, how to differentiate the header and footer from other contents in one page? Can anyone else tell me how?

Thanks in advance.

[Lei Zhang]

For the files you tested, do they have crop/trim/bleed/art boxes to
start with? Can you provide an example of a PDF to demonstrate the
issue?

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[Han Chipset]

Hi, Zhang

Thanks for your response.

I am not sure whether there are crop/trim/bleed/art boxes or not as I do not use any PDF editors. I downloaded the PDF files from Internet. Here are some.

https://www.nasa.gov/connect/ebooks/ebooks_archive_1.html

https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/PDF32000_2008.pdf

Then, there is another point. If there is no such boxes, using pdfium, how to identify header and footer in the pages of PDF files?

Thanks.

[Lei Zhang]

Many PDFs do not have these boxes. The crop box is relatively common.
e.g. PDF32000_2008.pdf has them. The others are much rarer. As such,
APIs like FPDFPage_GetBleedBox() will likely fail because the bleed
box simply does not exist.

If you read the PDF spec you linked to, section 7.7.3.3 explains the
bleed box is optional, and what the default value is when it does not
exist. PDFium APIs simply retrieve the box values if they exist. They
do not interpret the spec and fill in the default.

As for headers and footers on a page, in general, I don't think PDFs
have such a concept.

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