controllers/ViewPhoto.php

@@ -46,6 +46,19 @@ class ViewPhoto extends HTMLController
 		if (isset($tag))
 			$page->setTag($tag);
 
+		// Keeping tabs on a filter?
+		if (isset($_GET['by']))
+		{
+			// Let's first verify that the filter is valid
+			$contributors = array_filter($tag->getContributorList(), fn($el) => $el['slug'] === $_GET['by']);
+			if (count($contributors) !== 1)
+				throw new UnexpectedValueException('Invalid filter for this album or tag.');
+
+			// Alright, let's run with it then
+			$filter = reset($contributors);
+			$page->setActiveFilter($filter['slug']);
+		}
+
 		$this->page->adopt($page);
 		$this->page->setCanonicalUrl($this->photo->getPageUrl());
 	}

controllers/ViewPhotoAlbum.php

@@ -94,8 +94,15 @@ class ViewPhotoAlbum extends HTMLController
 		{
 			$index = new PhotosIndex($mosaic, Registry::get('user')->isAdmin());
 			$this->page->adopt($index);
-			if ($id_tag > 1)
-				$index->setUrlSuffix('?in=' . $id_tag);
+
+			$url_params = [];
+			if (isset($tag) && $tag->id_parent != 0)
+				$url_params['in'] = $tag->id_tag;
+			if (!empty($active_filter))
+				$url_params['by'] = $active_filter;
+
+			if (!empty($url_params))
+				$index->setUrlSuffix('?' . http_build_query($url_params));
 		}
 
 		// Make a page index as needed, while we're at it.

models/Asset.php

@@ -697,7 +697,7 @@ class Asset
 			$params);
 	}
 
-	protected function getUrlForAdjacentInSet($prevNext, ?Tag $tag)
+	protected function getUrlForAdjacentInSet($prevNext, ?Tag $tag, $activeFilter)
 	{
 		$next = $prevNext === 'next';
 		$previous = !$next;
@@ -722,6 +722,14 @@ class Asset
 			$params['order_dir'] = $previous ? 'ASC' : 'DESC';
 		}
 
+		// Take active filter into account as well
+		if (!empty($activeFilter))
+		{
+			$user = Member::fromSlug($activeFilter);
+			$where[] = 'id_user_uploaded = {int:id_user_uploaded}';
+			$params['id_user_uploaded'] = $user->getUserId();
+		}
+
 		// Use complete ordering when sorting the set
 		$where[] = '(a.date_captured, a.id_asset) {raw:where_op} ' .
 			'({datetime:date_captured}, {int:id_asset})';
@@ -740,22 +748,29 @@ class Asset
 			LIMIT 1',
 			$params);
 
-		if ($row)
-		{
-			$obj = self::byRow($row, 'object');
-			return $obj->getPageUrl() . ($tag ? '?in=' . $tag->id_tag : '');
-		}
-		else
+		if (!$row)
 			return false;
+
+		$obj = self::byRow($row, 'object');
+
+		$urlParams = [];
+		if (isset($tag))
+			$urlParams['in'] = $tag->id_tag;
+		if (!empty($activeFilter))
+			$urlParams['by'] = $activeFilter;
+
+		$queryString = !empty($urlParams) ? '?' . http_build_query($urlParams) : '';
+
+		return $obj->getPageUrl() . $queryString;
 	}
 
-	public function getUrlForPreviousInSet(?Tag $tag)
+	public function getUrlForPreviousInSet(?Tag $tag, $activeFilter)
 	{
-		return $this->getUrlForAdjacentInSet('previous', $tag);
+		return $this->getUrlForAdjacentInSet('previous', $tag, $activeFilter);
 	}
 
-	public function getUrlForNextInSet(?Tag $tag)
+	public function getUrlForNextInSet(?Tag $tag, $activeFilter)
 	{
-		return $this->getUrlForAdjacentInSet('next', $tag);
+		return $this->getUrlForAdjacentInSet('next', $tag, $activeFilter);
 	}
 }

templates/PhotoPage.php

@@ -8,6 +8,7 @@
 
 class PhotoPage extends Template
 {
+	private $activeFilter;
 	private $photo;
 	private $metaData;
 	private $tag;
@@ -78,6 +79,11 @@ class PhotoPage extends Template
 				</a>';
 	}
 
+	public function setActiveFilter($filter)
+	{
+		$this->activeFilter = $filter;
+	}
+
 	public function setTag(Tag $tag)
 	{
 		$this->tag = $tag;
@@ -85,14 +91,14 @@ class PhotoPage extends Template
 
 	private function photoNav()
 	{
-		if ($previousUrl = $this->photo->getUrlForPreviousInSet($this->tag))
+		if ($previousUrl = $this->photo->getUrlForPreviousInSet($this->tag, $this->activeFilter))
 			echo '
 				<a href="', $previousUrl, '#photo_frame" id="previous_photo"><i class="bi bi-arrow-left"></i></a>';
 		else
 			echo '
 				<span id="previous_photo"><i class="bi bi-arrow-left"></i></span>';
 
-		if ($nextUrl = $this->photo->getUrlForNextInSet($this->tag))
+		if ($nextUrl = $this->photo->getUrlForNextInSet($this->tag, $this->activeFilter))
 			echo '
 				<a href="', $nextUrl, '#photo_frame" id="next_photo"><i class="bi bi-arrow-right"></i></a>';
 		else