Overlays, underlays, watermarks, n-up¶
You can use pikepdf to overlay pages or other content on top of other pages.
This might be used to do watermarks (typically an underlay, drawn before everything else), n-up (compositing multiple individual pages on a large page, such as converting slides from a presentation to 4-up for reading and printing).
If you are looking to merge pages from different PDFs, see Merge (concatenate) PDF from several PDFs.
In this example we use
pikepdf.Page.add_overlay() to draw a thumbnail of
of the second page onto the first page.
In : from pikepdf import Pdf, Page, Rectangle In : pdf = Pdf.open(...) In : destination_page = Page(pdf.pages) In : thumbnail = Page(pdf.pages) In : destination_page.add_overlay(thumbnail, Rectangle(0, 0, 300, 300)) In : pdf.save("page1_with_page2_thumbnail.pdf")
pikepdf.Rectangle specifies the position on the target page into which
the other page can be drawn. The object will be drawn centered in a way that
fills as much space as possible while preserving aspect ratio.
pikepdf.Page.add_underlay() instead if you want content drawn underneath.
It is possible content drawn this way will be overdrawn by other objects.
pikepdf.Page.trimbox to get a page’s dimensions.
add_overlay will copy content across
add_overlay also preserves aspect ratio.
pikepdf.Page.calc_form_xobject_placement() if you want more precise control
Composition works using Form XObjects, which is how PDF captures of a group of related objects for drawing. Some very basic PDF software may not support them, or may fail to detect images contained within.
When perform n-up composition, it will work better to create your composition within the existing document, rather than in a new document. Transforming the existing document will ensure that metadata, annotations and hyperlinks are preserved. For example, to convert 16 slides to 4×4-up pages for printing, add four pages onto the end of the file, draw the slides onto the target pages, and then delete the slides.
add_overlay encapsulates the existing content stream in a way
that ensures the transformation matrix is first reset, since this behavior
aligns with user expectations. This adds a
q/Q pair to (push/pop graphics
stack) to existing content streams. To disable this (usually desired) behavior