ENH Improve quality of thumbnails in assetadmin and uploadfield

_config/config.yml

@@ -18,6 +18,7 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\AssetAdmin\Model\ThumbnailGenerator
     properties:
       Generates: true
+      thumbnailMethod: 'Fill'
   SilverStripe\AssetAdmin\Controller\AssetAdmin:
     properties:
       ThumbnailGenerator: '%$SilverStripe\AssetAdmin\Model\ThumbnailGenerator.assetadmin'
@@ -53,3 +54,4 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\AssetAdmin\Model\ThumbnailGenerator
     properties:
       Generates: false
+      thumbnailMethod: 'Fill'

code/Forms/UploadField.php

@@ -42,13 +42,13 @@ class UploadField extends FormField implements FileHandleField
      * @config
      * @var int
      */
-    private static $thumbnail_width = 60;
+    private static $thumbnail_width = 120;
 
     /**
      * @config
      * @var int
      */
-    private static $thumbnail_height = 60;
+    private static $thumbnail_height = 120;
 
     /**
      * Set if uploading new files is enabled.

code/GraphQL/Resolvers/FileTypeResolver.php

@@ -90,12 +90,27 @@ public static function resolveFileSmallThumbnail($object)
      */
     public static function resolveFileThumbnail($object)
     {
+        // If we're allowed to generate thumbnails for this file, tell the generator it's allowed to do it.
+        $generator = static::singleton()->getThumbnailGenerator();
+        $idsAllowed = FolderTypeResolver::getIdsAllowedToGenerateThumbnails();
+        $shouldGenerateThumbnail = !empty($idsAllowed) && in_array($object->ID, $idsAllowed);
+        if ($shouldGenerateThumbnail) {
+            $origGenerates = $generator->getGenerates();
+            $generator->setGenerates(true);
+        }
+
         // Make large thumbnail
         $width = AssetAdmin::config()->uninherited('thumbnail_width');
         $height = AssetAdmin::config()->uninherited('thumbnail_height');
-        return static::singleton()
-            ->getThumbnailGenerator()
-            ->generateThumbnailLink($object, $width, $height);
+
+        try {
+            return $generator->generateThumbnailLink($object, $width, $height);
+        } finally {
+            // Make sure to set the generates value back to what it was, regardless of what happens
+            if ($shouldGenerateThumbnail) {
+                $generator->setGenerates($origGenerates);
+            }
+        }
     }
 
     /**

code/GraphQL/Resolvers/FolderTypeResolver.php

@@ -18,10 +18,20 @@
 use InvalidArgumentException;
 use Exception;
 use Closure;
+use SilverStripe\AssetAdmin\Controller\AssetAdmin;
 use SilverStripe\ORM\DataQuery;
 
 class FolderTypeResolver
 {
+    /**
+     * Any IDs of files which we're allowed to generate thumbnails for.
+     * The intention is to (as much as is feasible) only allow generating thumbnails
+     * during asset admin graphQL requests and not for requests that could be performed
+     * by an attacker.
+     * @internal
+     */
+    private static array $idsAllowedToGenerateThumbnails = [];
+
     /**
      * @param Folder $object
      * @param array $args
@@ -73,6 +83,17 @@ public static function resolveFolderChildren(
         $canViewList = $list->filter('ID', $canViewIDs ?: 0)
             ->limit(null);
 
+        // If we haven't already marked IDs as being okay to generate thumbnails,
+        // and we have a safe limit for the number of children,
+        // mark these children as being okay to generate thumbnails for.
+        if (empty(self::$idsAllowedToGenerateThumbnails)
+            && !empty($args['limit'])
+            && is_numeric($args['limit'])
+            && (int)$args['limit'] <= AssetAdmin::config()->get('page_length')
+        ) {
+            self::$idsAllowedToGenerateThumbnails = $canViewIDs;
+        }
+
         return $canViewList;
     }
 
@@ -181,4 +202,9 @@ public static function sortChildren(array $context): Closure
             return $list;
         };
     }
+
+    public static function getIdsAllowedToGenerateThumbnails(): array
+    {
+        return self::$idsAllowedToGenerateThumbnails;
+    }
 }

code/Model/ThumbnailGenerator.php

@@ -60,11 +60,16 @@ class ThumbnailGenerator
     ];
 
     /**
-     * @var string
-     * @config
+     * @var string The default method to use for generating thumbnails if a specific method hasn't been
+     * set for a given generator instance.
      */
     private static $method = 'FitMax';
 
+    /**
+     * The method that this generator instance will use to generate thumbnails.
+     */
+    private string $thumbnailMethod = '';
+
     /**
      * Generate thumbnail and return the "src" property for this thumbnail
      *
@@ -108,7 +113,7 @@ public function generateThumbnail(AssetContainer $file, $width, $height)
         }
 
         // Make large thumbnail
-        $method = $this->config()->get('method');
+        $method = $this->getThumbnailMethod();
         return $file->$method($width, $height);
     }
 
@@ -173,4 +178,25 @@ public function setGenerates($generates)
         $this->generates = $generates;
         return $this;
     }
+
+    /**
+     * Get the method which will be used to generate thumbnails.
+     */
+    public function getThumbnailMethod(): string
+    {
+        if ($this->thumbnailMethod) {
+            return $this->thumbnailMethod;
+        }
+        return static::config()->get('method');
+    }
+
+    /**
+     * Set the method which will be used to generate thumbnails.
+     * Pass an empty string to reset to the default method.
+     */
+    public function setThumbnailMethod(string $method): static
+    {
+        $this->thumbnailMethod = $method;
+        return $this;
+    }
 }