cmake script to auto download and install the openjpeg dependency

[grdanny]

Description

sub task of : #4387
for sep 2025 dev days.

Adding a autobuild cmake file for openjpeg.

Matching the latest version like in the yet unmerged:
#4910

Tests

I built it locally - I can see it's downloading the files from github and building them.
I can run the tests.

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable. (Check if there is no
  need to update the documentation, for example if this is a bug fix that
  doesn't change the API.)
• I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• If I added or modified a C++ API call, I have also amended the
  corresponding Python bindings (and if altering ImageBufAlgo functions, also
  exposed the new functionality as oiiotool options).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format before submitting, I definitely will look at the CI
  test that runs clang-format and fix anything that it highlights as being
  nonconforming.

[lgritz]

I think this is correct, but in ci.yml, in the "all local builds" job, you'll want to remove the setting of env variable OPENJPEG_VERSION=v2.5.4 because that will trigger the external script build_OpenJPEG.bash before the build. You don't want that, in this case you want to be sure you're forcing the autobuild one.

[lgritz]

I pushed some fixes to the OpenJPEG build methodology. It was all about getting correct static libraries built and recognized.

[grdanny]

I see, so if I'm running the bash script the does the OpenJpeg build and install I end up with these files:

oiio/ext/dist/lib64/pkgconfig/libopenjp2.pc
oiio/ext/dist/lib64/libopenjp2.a
oiio/ext/dist/lib64/libopenjp2.so
oiio/ext/dist/lib64/libopenjp2.so.7
oiio/ext/dist/lib64/libopenjp2.so.2.5.4

So basically we are telling the OpenImageIO build to prefer the "libopenjp2.a"?

Thanks for the help with this.

[grdanny]

this looks good to me now if it looks good to you btw. Thanks again.

[lgritz]

Aha, thanks for reminding me about the bash script. I need to adjust that, too.

[lgritz]

I pushed one more amendment, to build_OpenJPEG.bash:

• Build it with position independent code always (lets us use the static library from a dynamic library).
• Allow a control to optionally disable building the dynamic libs.

That's for the bash script. The cmake auto-builder already does this (in my prior patch) and should default to the static library.

[lgritz]

Seems to fully work now

[lgritz]

Wait, I think I need one more adjustment. Stay tuned.

[lgritz]

I think it all works now

[grdanny]

Thanks for helping me take this to the finish line.