3.6: support PDF with brotli compression

[kjk]

In latest 3.6 pre-release I've added support for brotli compression in PDF files.

This is not yet a standard feature of PDF but it'll likely become at some point (read https://grok.com/share/bGVnYWN5_98c3b7b1-f761-46be-aec6-eef7e562bebf for more details).

The advantage of using brotli compression is smaller PDF files (compared to uncompressed files or those compressed with zlib/deflate compression).

[MengXiangxi]

Cool! There is finally a new version coming out after such a long time of waiting!

[GitHubRulesOK]

@MengXiangxi whilst one day from 2025 to 2026 is a whole year that is not "a long tine of waiting" SumatraPDF is naturally a stop/start timescale and a New release may never be "tomorrow" but more than likely "this year"

[rmmbr]

"this year" ...

There are many things in the prerelease since version 3.5.2 that I would like to have now. However, for production use, I would prefer a release. In my opinion, it's about time ...

[GitHubRulesOK]

@rmmbr
The only real difference between current pre-release and a formal release is a "fixed" release has the same bugs for a looong time, but a pre-release in production will have changes from one hour or year to the next release. Personally I have a set of pre-releases to go back to a prior pre-release such as 17059 if my production pre-release 17127 copy has a new issue.

A formal release provides for a larger number of users and thus less likely to be triggered by defender as "dubious" (warns do you really want to use this lesser known variation) but that is only down to number of users of a single variation.

[rmmbr]

@GitHubRulesOK
This approach would be highly unprofessional if more than one computer needed to be supported. I don't even want to think about larger organizations. Thanks for the heads-up anyway.

[asjones987]

It sounds like the standard is still evolving. Did you add support with a 3rd party module that is updated if the standard is changed?

[GitHubRulesOK]

@asjones987 MuPDf had experimental Brotli for as long as it was mooted but only recently added the experimental formats as per their samplers and SumatraPDF has now exposed their most recent usage. So if MuPDF changes with newer variants then SumatraPDF should after a while follow those same variations.

Thus at the moment Chrome/Edge (with Acrobat code) do not support PDFs with Brotli even if Google wrote it over 10 years ago. you can see my discussion here https://stackoverflow.com/a/79847677/10802527