CODEWITHSUNDEEP
.net-core
Piotr Perak
Piotr Perak

Reputation: 11088

Read pdf page size on .NET Core

I have only one requirement. I need to read PDF page size and determine if page is not bigger then 17x17 inches to not send it to some external service which rejects such pdfs.

Is there any free library working on .NET Core? I wasn't able to find it. Or maybe anyone implemented this by reading binary file?

Upvotes: 0

Views: 262

Answers (1)

K J
K J

Reputation: 11846

A PDF does not have to declare page size externally since every page can be a different size thus 100 pages may be 100 different page sizes.

However many PDF will contain a text entry for one or more pages so you can (depending on construction) parse as text for /MediaBox and or potentially /CropBox dimensions.

So the first PDF example I pick on and open to search for /MediaBox in WordPad tells me its 210 mm x 297 mm (i.e my local A4) /MediaBox [0 0 594.95996 841.91998] and for a 3 page file all 3 entries are the same.

you can try that using command line as

type "filename.pdf" | find /i "/media"

but may not work in all cases so a bigger chance of result (but more chaff) is

type "filename.pdf" | findstr /i "^/media ^/crop"

The value is based on the default number of point size units per inch (so can be divided by 72 as a rough guide), however, that's not your aim since you know you don't want more that 17x72=1224.

So in simple terms, if either value was over 1224 then I could reject as "TOO BIG".

However I need to also consider those two 0 values, thus if one was +100 then the limit becomes 100 more and more importantly, if one was -100 then your desired 17" restriction will fail at 1124.

So you can write in any method or language (even CMD) a simple test, however, that will require too much expanding to cover all cases, SO:-

I would use a one-line command tool like xpdf/poppler pdfinfo to parse all different types of PDF and then grep that output.

The output is similar for both with many lines but for your need

xpdf\pdfinfo -box filename

gives Page size: 594.96 x 841.92 pts (A4) (rotated 0 degrees)

and

poppler\pdfinfo -box filename

gives Page size: 594.96 x 841.92 pts (A4)

Thus to check the file does not exceed 17" (in either direction) it should be easy to set a comparison testing that both values are under 1224.01

Upvotes: 2

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