Azure Image OCR

[dkotter]

Description of the Change

Add support for Azure image OCR.

Adds a new setting that is turned off by default but can be turned on to run OCR scanning on images. When an image is initially uploaded, we run a few checks on that image. First, we check if the image matches one of the supported types (JPEG, PNG, GIF, BMP). If so, we then check if we have a previous image scan and if so, we check if we have either the handwriting or text tags set, with a high confidence level (above 90%). If all those checks pass, we then run OCR scanning.

If we get a successful response back, we then parse the text out of that response, save that text to wp_content for that image and then save the full response to post meta.

We also add scan/recan functionality to the media modal and single media edit screens. If a scan is run from here, we bypass our checks, as we assume if someone is manually starting a scan, they don't care about the checks. Also added some better error handling to the scan/rescan buttons, so if a scan fails, we don't continue to show the loading icon but instead remove that, keep the button disabled and change the button text to say error (ideally we would add even better error handling in a separate PR). This is now in a separate PR: #231

TODO: last piece is to add describedby text into the content when needed. Need to support the block editor and the classic editor

Alternate Designs

Benefits

Images with text can now have that text automatically read and then inserted into the content, with the proper describedby tags. This helps provide more context for images, especially images that are screenshots of text (like social media posts).

Possible Drawbacks

With this feature turned on, will cause a slight slowdown (seems like roughly 5 extra seconds), in image processing.

Verification Process

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

#111

[jeffpaul]

Noting here that @dinhtungdu is going to work on scaffolding in the Gutenberg bits

[helen]

This is feeling pretty good to me for a first run. I think what we might want to do is add a field to wp_prepare_attachment_for_js() that's a bool for whether classifai_computer_vision_ocr is non-empty (like classifaiHasOcr or something) and only show the prompt in that case, not just if the description field is populated because that description field could be populated manually or from unrelated EXIF data.

[dinhtungdu]

@helen I fixed the REST API response issue. This PR is working on my live site.

[helen]

Nice work here, everybody!