Keep reference to metadata before regenerating images.

[aaronfc]

Fixes #136

Description of the change

Starting from WP 5.3 "sizes" attribute on metadata is reset to empty when passed to intermediate_image_sizes_advanced filter. The fix saves temporarily the metadata for the original file before calling the intermediate_image_sizes_advanced filter, so we can keep the same logic that was being applied before.

Alternatives

I have been tempted to just remove the check for metadata sizes completely. I don't quite understand why it was introduced and doesn't seem really needed to me. But I finally decided to keep logic the same.

Testing instructions

• Checkout to the branch.
• Run yarn (see detailed instructions below).
• Upload some images to the media library.
• Go to Tools > Regenerate Thumbnails.
• Make sure the option "Skip regenerating existing correctly sized thumbnails (faster)." is marked.
• Click on Regenerate Thumbnails for ... button.
• Check that the images are not regenerated – you can do that by going manually to the wp-content/uploads/... folder and checking that the file modification time does not change.

Extra details on build step (troubleshooting)

I had some trouble setting up the development environment – here are the details I followed:

• Open terminal using Rosetta with arch -x86_64 zsh.
• nvm install v8 && nvm use v8.
• npm install yarn --no-save
• node_modules/.bin/yarn
• node_modules/.bin/yarn build

[MarcGuay]

My understanding of the need for checking the metadata sizes is that is how we know which sizes the image is supposed to have matching files for. Once we know what sizes we should have, then we can know which ones already have existing files and don't need to be regenerated.

[aaronfc]

My understanding of the need for checking the metadata sizes is that is how we know which sizes the image is supposed to have matching files for. Once we know what sizes we should have, then we can know which ones already have existing files and don't need to be regenerated.

Thanks for your input, @MarcGuay. Let me develop a bit further my concern below.

If I am not missing anything, the sizes we "expect" are passed to the intermediate_image_sizes_advanced hook as its first parameter. Then, as you mentioned, we check the sizes in the metadata here and here.

But the thing is that, we are already doing something similar in the get_thumbnail method called here. Since we are generating the filename based on the expected sizes and later it's checked if the file_exists.

It's not exactly the same, but I see it just as an extra measure in case the file existed (with the expected image dimensions in the file name) but having different real dimensions.

Anyway, I think that explaining it out loud here made me convince that it's not that bad to keep the extra check. Thanks for commenting on it!

[ddur]

There is another regenerate thumbnails issue created by WP 5.3 disaster changes. You have opportunity to fix it now. Issue https://github.com/Automattic/regenerate-thumbnails/issues/102

[aaronfc]

There is another regenerate thumbnails issue created by WP 5.3 disaster changes. You have opportunity to fix it now. Issue https://github.com/Automattic/regenerate-thumbnails/issues/102

Hey @ddur, thanks for your feedback. I would rather have the issues separated. Hopefully we will be able to work on that one soon. Meanwhile, just a reminder that you can raise a PR yourself if you have a clear solution in mind.