Page properties extraction

[meghanaviyyapu]

Can you let me know how page margin values (left,top,right,bottom) can be extracted from PDF?

[JorjMcKie]

There is no such thing.
You can however determine the union of all text bboxes easily by computing them e.g. from get_text("blocks").
Or build other types of sub areas in similar ways (drawings, images, ...).

[JorjMcKie]

Then, according to your logic the bottom "margin" is margins.y1 (or rather the difference page.rect.height margins.y1). And top is margins.y0.

I cannot image why you would want this info at all. But given you need it, you should probably build the union of text rectangles for every page and take the maximum rect (i.e. the union) of all those across all pages.

[meghanaviyyapu]

I have modified the logic for top and bottom margins. The actual margin values of the input PDF are (left 36pt, right 72pt, top 108pt, bottom 180pt) but only the left margin value seems to be accurate using the below logic.

margin1.pdf

Can a PDF be created from an existing PDF without specifying margin values?

[JorjMcKie]

The actual margin values of the input PDF are (left 36pt, right 72pt, top 108pt, bottom 180pt)

Who told you that? In PDF, there exists no such concept like a "margin".

Can a PDF be created from an existing PDF without specifying margin values?

Of course, because a PDF page has no such thing like a "margin". Such values are not stored anywhere in a PDF document. So you cannot find them. The best approximation you can ever get, is what I explained already.
If you believe you have better insight, please tell me where to find such values.

only the left margin value seems to be accurate

No, all values are correct!

[meghanaviyyapu]

I found a code to create a PDF with margins using a library called OpenPDF.
Document document = new Document(PageSize.A5, 36, 72, 108, 180);
Here 36, 72, 108, 180 are margin values. If a PDF is created without specifying these values, will there be any effect on alignment of text?

[JorjMcKie]

without specifying these values, will there be any effect on alignment of text?

Presumably yes.
But this does not mean that you can extract those values from the PDF again once it has been created!