PPF-1144: Provide user feedback while running

[flywire]

Version

PyPDFForm=3.4.0

Issue Description

There is no response on screen when PyPDFForm is running. User has no way of knowing if it is still running.

[chinapandaman]

I'm not sure what you mean by this. PyPDFForm is a library. It's not a service/framework, and is up to whoever is invoking PyPDFForm to make the decision whether they want to let the user that's using their code to know if PyPDFForm is part of their code.

[flywire]

Fair enough. One of the forms is taking over an hour to add fields using the script generated by markup.py.

How can PyPDFForm be run for the best performance? Can you give me any tips (possibly a little code) to get some screen feedback without degrading performance too much?

[chinapandaman]

If you are creating a large number of fields in an iterate fashion then it's expected to take long. Right now create_widget method is not optimized for many form fields creation.

For now if your template is only meant to be created once before filling, consider storing the generated template. Otherwise at some point in the future there are plans to implement a bulk create fields method that's supposedly more performance optimal.

[flywire]

How can PyPDFForm be run for the best performance?

I tested BytesIO referred to in https://chinapandaman.github.io/PyPDFForm/install/#write-to-a-file but it was running at least 10 times slower so I just killed the run.

[chinapandaman]

It has nothing to do with BytesIO, the .write method works exactly the same way under the hood.

The problem right now is every time you create a field, there is a reportlab canvas created, then that field is created on the canvas, and finally the canvas is merged with the original PDF. This process is extremely expensive, and even more so if you are doing it in large number of iterations.

The ideal way of doing bulk creation (the implementation I said I would finish some time in the future) would be to buffer up all the field creation parameters for all the fields needed to be created, then just create one canvas, create those fields on that canvas, and merge just one canvas with the original PDF. This will by nature much faster.

[flywire]

just create one canvas, create those fields on that canvas, and merge just one canvas with the original PDF

Yes, that's how markup.py works for markup of points and ids . It's almost instant.

I look forward to your future work.