RFR: 8160327: Support for thumbnails present in APP1 marker for JPEG [v3]

[Jeremy]

On Fri, 21 Feb 2025 02:31:42 GMT, Jeremy <duke at openjdk.org> wrote:

>> This adds support for parsing thumbnails in an APP1 Exif marker.
>> 
>> This builds on an unfinished proposal by Brian Burkhalter (around 2016). In that previous work the only additional meta info he parsed was the image creation time; this PR similarly includes the same property. (I can't speak to why he included that property, but it looks like he has a lot of experience with ImageIO so I trust his judgment.)
>> 
>> The test addresses the original images attached to the ticket plus a few extra images I found on my computer that include unusual properties. (Possibly those images are malformed, but if they exist in the wild and other platforms support them then I'd prefer to support them too.)
>
> Jeremy has updated the pull request incrementally with four additional commits since the last revision:
> 
>  - 8160327: alphabetize imports
>    
>    This is in response to:
>    https://github.com/openjdk/jdk/pull/22898#discussion_r1956718373
>  - 8160327: fallback to using MarkerSegment if ExifMarkerSegment fails
>    
>    This is in response to:
>    https://github.com/openjdk/jdk/pull/22898#discussion_r1955194737
>    
>    "I would have supposed that if there's an Exif segment we don't like it would be best to just act like the segment isn't there."
>  - 8160327: include support for JFIF *and* EXIF thumbnails together
>    
>    This is in response to:
>    https://github.com/openjdk/jdk/pull/22898#issuecomment-2666324177
>    
>    As mentioned here ( https://github.com/openjdk/jdk/pull/22898#issuecomment-2666949882 ) we'll need to update some documentation about thumbnails.
>  - 8160327: moving test + resources to separate directory
>    
>    This is in response to:
>    https://github.com/openjdk/jdk/pull/22898#issuecomment-2657721887

I don't know how to initiate a CSR. Is that something I can initiate, or does that require a more senior sponsor?

I'm not done with the test files yet. (I'll make a note in this PR when I am.)

Regarding sample files:
I replaced the jpeg file that embeds a JFIF *and* EXIF thumbnail. I still need to:
A. replace the jpeg file "exif-rgb-thumbnail" and
B. review this thread for other interesting test cases

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PR Comment: https://git.openjdk.org/jdk/pull/22898#issuecomment-2675814497