Add support for LZWDecode compression

[Lucas-C]

Please explain your intent
Currently fpdf2 supports 4 compression methods for images:
https://github.com/py-pdf/fpdf2/blob/2.8.0/fpdf/image_parsing.py#L35

The PDF standard specification (cf. PDF32000_2008.pdf section 7.4 Filters) defines several other compression filters, including LZWDecode.

Recently, this filter was implemented by @MartinThoma in our companion library pypdf: py-pdf/pypdf#2883

Describe the solution you'd like
Support LZWDecode for images compression.

[opposss]

Hi!

I'd love to work on this issue can you assign me?

[Lucas-C]

Sure, done!

[Lucas-C]

Hi @opposss

Have you been able to start working on this implementation?
Do you have any questions?

[opposss]

Hi @Lucas-C

Almost done, I will send the PR for review soon.
Before that I would like to ask 2 questions:

1. Do I understand correctly that I can completely use the code that was written by @MartinThoma ?

2. Should I add logic to use the LZW filter in case of GIF images or other image formats?

[Lucas-C]

Almost done, I will send the PR for review soon.

Great! 👍

1. Do I understand correctly that I can completely use the code that was written by @MartinThoma ?

Yes!

2. Should I add logic to use the LZW filter in case of GIF images or other image formats?

If you can find a mention that this is supported, in the PDF spec (PDF32000_2008.pdf), or that main PDF readers support it (Adobe Acrobat, Sumatra PDF, MuPDF, web browsers...), then yes!

[Lucas-C]

This was implemented by @opposss in PR #1286

[Lucas-C]

This feature has been included in the new release published today:
https://github.com/py-pdf/fpdf2/releases/tag/2.8.2