Implement Image Properties feature of the Vision API

Mhh, I think that if nodes have images with the same colors, then these nodes are not actually similar. I don't know how it can help to the end user.
In my opinion, more useful functionality is the search of the similar images by colors.
What do you think? Can you try to propose another useful cases?

We shouldn't just write the code, we should help to the end users.

1. +++ b/google_vision.module
   @@ -29,6 +31,21 @@ function google_vision_entity_presave(EntityInterface $entity) {
   +            $vocabularies = \Drupal\taxonomy\Entity\Vocabulary::loadMultiple();
   

   use this class above and then only use "Vocabulary::loadMultiple"

2. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,73 @@
   +    $query = \Drupal::database()->select('file_managed', 'fm');
   

   inject the connection object.

3. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,73 @@
   +    $query->condition('vid', "dominant_color");
   

   why double quotes and single quotes

4. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,73 @@
   +    $terms = \Drupal\taxonomy\Entity\Term::loadMultiple($tids);
   

   use the Term class at the top and only use "Term::loadMultiple($tids)"

5. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,73 @@
   +      $query = \Drupal::database()->select('file__field_labels', 'ffl');
   

   inject the connection object here.

+++ b/google_vision.module
@@ -29,6 +31,23 @@ function google_vision_entity_presave(EntityInterface $entity) {
+              $vocabulary = \Drupal\taxonomy\Entity\Vocabulary::create(array(

use this class and only use "Vocabulary::create" method instead.

1. +++ b/google_vision.links.task.yml
   index 3d722fa..551e03b 100644
   --- a/google_vision.module
   

   While you are on this file. Please either remove the @file doc or add the description about the file.

2. +++ b/google_vision.module
   @@ -102,6 +121,53 @@ function google_vision_form_field_config_form_image_builder($entity_type, FieldC
   +  $query = \Drupal::database()->select('taxonomy_term_field_data', 'tfd');
   

   can we use the \Drupal::entityQuery here ?

3. +++ b/google_vision.module
   @@ -102,6 +121,53 @@ function google_vision_form_field_config_form_image_builder($entity_type, FieldC
   +  $file->set($field->getName(), $values);
   

   declare $values as an empty [] before foreach. if none of the condition met then it will throw error.

4. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,105 @@
   +  /**
   

   Add a new line before doc comment.

5. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,105 @@
   +   * Get the file title.
   

   Add the @param & @return types here.

6. +++ b/src/Controller/SimilarContentController.php
   @@ -0,0 +1,105 @@
   +   * Returns the list of image links which share the same dominant color.
   

   Same as above. Add the @param and @return type here.

Applied with some corrections.
Be careful, better to try to load vocabulary directly $vocabulary = Vocabulary::load($vid); instead of loading all the vocabularies.

      foreach ($files as $key => $value) {
        $build[$key] = [
          '#prefix' => '<li>',
          '#type' => 'link',
          '#title' => $this->getFileTitle($key),
          '#url' => Url::fromRoute('entity.file.canonical', ['file' => $key]),
          '#suffix' => '</li>',
        ];
      }

Multiple queries to DB in the cycle are awful. Never do it. Please correct to one query.

      $build['#prefix'] = '<ul>';
      $build['#suffix'] = '</ul>';

      foreach ($files as $key => $value) {
        $build[$key] = [
          '#prefix' => '<li>',
          '#type' => 'link',
          '#title' => $this->getFileTitle($key),
          '#url' => Url::fromRoute('entity.file.canonical', ['file' => $key]),
          '#suffix' => '</li>',
        ];
      }

I believe that you can render the list not through prefix and suffix but through something like "item_list" please investigate this point.

return (int) db_query('SELECT MAX(fid) FROM {file_managed}')->fetchField();

db_query is deprecated. Don't use it.

I think that for route google_vision.related_content you should use permission 'administer files', because actually it's the list of the files and it's not related to administration of the google vision. I did it.

looks better
Thanks

Patch committed and pushed to 8.x-1.x
Thanks!

I think that the name of this feature is confusing. Dandelion and sand can have the same color. But hardly ever somebody will think that these images are similar.
Please improve instruction, info on the module page and text in interface to let the end user understand this feature better.

Filed a followup for the same https://www.drupal.org/node/2783939