[bob1029]

We have to fill existing PDFs from a wide range of vendors and clients. Our approach is to raster all PDFs to 300DPI PNG images before doing anything with them.

Once you have something as a PNG (or any other format you can get into a Bitmap), throwing it against something like System.Drawing in .NET(core) is trivial. Once you are in this domain, you can do literally anything you want with that PDF. Barcodes, images, sideways text, html, OpenGL-rendered scenes, etc. It's the least stressful way I can imagine dealing with PDFs. For final delivery, we recombine the images into a PDF that simply has these as scaled 1:1 to the document. No one can tell the difference between source and destination PDF unless they look at the file size on disk.

This approach is non-ideal if minimal document size is a concern and you can't deal with the PNG bloat compared to native PDF. It is also problematic if you would like to perform text extraction. We use this technique for documents that are ultimately printed, emailed to customers, or submitted to long-term storage systems (which currently get populated with scanned content anyways).

[rahimnathwani]

You could probably reduce file size by generating your additions as a single PDF, and then combining that with the original 'form', using something like

pdftk form.pdf multibackground additions.pdf output output.pdf

[mopsi]

> No one can tell the difference between source and destination PDF unless they look at the file size on disk.

Not even when they try to select and copy text?

[hnick]

You can add PDF tag commands to make rasterised text selectable and searchable, though they probably aren't doing that.

[equasar]

Any recommended library for .NET to extract text by coordinates?

[Rury]

There's itext7 (also for java). Not sure how it compares with other libraries, but it will parse text along with coordinates. You just need to write your own execution strategy to parse how you want.

From my experience, it seems to grab text just fine, the tricky part is identifying & grabbing what you want, and ignoring what you don't want... (for reasons mentioned in the article)

https://github.com/itext/itext7-dotnet

https://itextpdf.com/en/resources/examples/itext-7/parsing-p...

[bob1029]

I don't know that this could exist for all PDFs.

Sounds like you are in need of OCR if you want to be able to use arbitrary screen coords as a lookup constraint.