Added file modification timestamps for media images

system/src/Grav/Common/Page/Medium/AbstractMedia.php

@@ -62,6 +62,22 @@ abstract class AbstractMedia extends Getters implements MediaCollectionInterface
         return $object;
     }
 
+    /**
+     * Set file modification timestamps (query params) for all the media files.
+     *
+     * @param string|int|null $timestamp
+     * @return $this
+     */
+    public function setTimestamps($timestamp = null)
+    {
+        /** @var Medium $instance */
+        foreach ($this->instances as $instance) {
+            $instance->setTimestamp($timestamp);
+        }
+
+        return $this;
+    }
+
     /**
      * Get a list of all media.
      *

system/src/Grav/Common/Page/Medium/Medium.php

@@ -112,6 +112,35 @@ class Medium extends Data implements RenderableInterface, MediaObjectInterface
         return false;
     }
 
+    /**
+     * Get file modification time for the medium.
+     *
+     * @return int|null
+     */
+    public function modified()
+    {
+        $path = $this->get('filepath');
+
+        if (!file_exists($path)) {
+            return null;
+        }
+
+        return filemtime($path) ?: null;
+    }
+
+    /**
+     * Set querystring to file modification timestamp (or value provided as a parameter).
+     *
+     * @param string|int|null $timestamp
+     * @return $this
+     */
+    public function setTimestamp($timestamp = null)
+    {
+        $this->set('querystring', (string)($timestamp ?? $this->modified()));
+
+        return $this;
+    }
+
     /**
      * Returns an array containing just the metadata
      *

system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php

@@ -73,7 +73,7 @@ trait FlexMediaTrait
             }
         }
 
-        return $this->media;
+        return $this->media->setTimestamps();
     }
 
     public function checkUploadedMediaFile(UploadedFileInterface $uploadedFile)