Usually you would not index images by themselves, instead you would index images as part of a webpage. For this page, it looks like this:
 

  1. <url>
  2. <loc>http://gbyte.co/blog/image-indexation-new-features-simple-xml-sitemap-2.10</loc>
  3. <xhtml:link href="http://gbyte.co/blog/image-indexation-new-features-simple-xml-sitemap-2.10" hreflang="en" rel="alternate">
  4. <lastmod>2017-12-12T22:36:26+01:00</lastmod>
  5. <changefreq>weekly</changefreq>
  6. <priority>0.7</priority>
  7. <image:image>
  8. <image:loc>http://gbyte.co/sites/default/files/public/images/blog/sitemap_8_0_0.png</image:loc>
  9. </image:image>
  10. <image:image>
  11. <image:loc>http://gbyte.co/sites/default/files/public/inline-images/bundle_settings_2_0.png</image:loc>
  12. </image:image>
  13. </xhtml:link>
  14. </url>

So if you have an accessible index page of these images, you can use hook_simple_sitemap_arbitrary_links_alter to add that page and its images like shown above, or, if it is a routed page, just add it to the index and use hook_simple_sitemap_links_alter to add images to it.

But if you are serious about the image drop functionality, the best thing would be to build this functionality in a way which makes Drupal know the images. I implemented this functionality on gbyte.co to share documents and images with my clients. There is some custom code involved, but most of the work is done by these modules:

  • ACL
  • Content Access
  • Download
  • User Protect

ACL and Content Access handle the permissions, Download makes it possible to download all the files attached to an entity. I also implemented group accounts where many people can use the same credentials to log in to their files. To prevent them from editing the account, the User Protect module can be utilized.

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