Fix bitfield PixelFormatFlags

[sisco0]

Solves https://github.com/WerWolv/ImHex/issues/1744

Pattern

PixelFormatFlags, which is part of DDS_PIXELFORMAT is an already present bitfield which requires of re-work. The following actions were performed over the given bitfield:

1. Proper bitfield names were added instead of padding, adding a clear representation of each flag.
2. Comments are added for each one of the bitfield elements.
3. luminance field is now properly aligned.

For more information about the current re-worked bitfield, consult Direct-Draw Surface flags definition at GIMP.

Checklist

• [x] A pattern for this format doesn't exist yet (or this PR improves the existing one)
• [ ] The new pattern has been added to the relevant table in the Readme
• [ ] The new pattern has a description pragma (#pragma description My pattern Description here)
• [ ] The pattern was associated with all relevant MIME types (using #pragma MIME mime-type in the source code)
  • Make sure to never use application/octet-stream here as that means "Unidentifiable binary data"
• [ ] A test file for this pattern has been added to /tests/patterns/test_data
  • Try to keep this file below ~ 1 MB

[WerWolv]

Thanks a lot! Is it important that the values of the padding fields are shown? padding is a special keyword otherwise that simply skips those bits without them being shown in the pattern data view.

[sisco0]

Thank you for your kind review @WerWolv . I have now re-worked the current Pull Request with proper values after consulting GIMP repository. Only one padding is left, and that is presented at the end of the current bitfield with the name padding for not showing it.

[sisco0]

I would re-factor the current Pull Request to contain a test, so ideally I could learn more from the repository structure and could provide evidence.

[WerWolv]

There's already a test file in the repo that the current pattern is being run on to make sure it runs correctly. But you can add some std::assert() calls to the pattern file to verify values if there's any good candidates

[sisco0]

I attach graphic evidence of the file under test folder with positive results compared to current GIMP implementation in this comment: