Preliminary implementation of Special:SubcatImagesGallery

This can be used to add the link "Show images from subcategories"
to category pages.

RelatedImages.alias.php

@@ -0,0 +1,14 @@
+<?php
+
+/**
+ * Aliases for Special:SubcatImagesGallery
+ *
+ * @file
+ */
+
+$specialPageAliases = [];
+
+/** English */
+$specialPageAliases['en'] = [
+	'SubcatImagesGallery' => [ 'SubcatImagesGallery' ]
+];

extension.json

@@ -10,7 +10,11 @@
 	},
 	"type": "other",
 	"AutoloadClasses": {
-		"MediaWiki\\RelatedImages\\Hooks": "includes/Hooks.php"
+		"MediaWiki\\RelatedImages\\Hooks": "includes/Hooks.php",
+		"MediaWiki\\RelatedImages\\SpecialSubcatImagesGallery": "includes/specials/SpecialSubcatImagesGallery.php"
+	},
+	"ExtensionMessagesFiles": {
+		"RelatedImagesAlias": "RelatedImages.alias.php"
 	},
 	"HookHandlers": {
 		"main": {
@@ -71,6 +75,10 @@
 		"RelatedImagesDoNotRecommendExtensions": {
 			"value": [ "ogg", "pdf" ],
 			"description": "Related Images box won't recommend files with these file extensions."
+		},
+		"RelatedImagesMaxSubcatImages": {
+			"value": 100,
+			"description": "Maximum number of additional thumbnails to show when user clicks \"Show images from subcategories\" link on category pages."
 		}
 	},
 	"ResourceModules": {
@@ -104,5 +112,13 @@
 		"localBasePath": "modules",
 		"remoteExtPath": "RelatedImages/modules"
 	},
+	"SpecialPages": {
+		"SubcatImagesGallery": {
+			"class": "MediaWiki\\RelatedImages\\SpecialSubcatImagesGallery",
+			"services": [
+				"DBLoadBalancer"
+			]
+		}
+	},
 	"manifest_version": 2
 }

i18n/en.json

@@ -8,5 +8,6 @@
 	"relatedimages-desc": "Displays \"Related images\" navigation box on File pages.",
 	"relatedimages-header": "Related media",
 	"relatedimages-more": "Show more",
-	"relatedimages-more-loading": "Loading..."
+	"relatedimages-more-loading": "Loading...",
+	"subcatimagesgallery-empty": "No images found."
 }

includes/specials/SpecialSubcatImagesGallery.php

@@ -0,0 +1,111 @@
+<?php
+
+/**
+ * Implements RelatedImages extension for MediaWiki.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+namespace MediaWiki\RelatedImages;
+
+use ImageGalleryBase;
+use Title;
+use UnlistedSpecialPage;
+use Wikimedia\Rdbms\ILoadBalancer;
+
+/**
+ * Implements hidden special page [[Special:SubcatImagesGallery/CategoryNameHere]],
+ * which returns HTML of the gallery of images from subcategories of CategoryNameHere.
+ * This can be used to add the link "Show images from subcategories" to category pages.
+ */
+class SpecialSubcatImagesGallery extends UnlistedSpecialPage {
+	/** @var ILoadBalancer */
+	protected $loadBalancer;
+
+	/**
+	 * @param ILoadBalancer $loadBalancer
+	 */
+	public function __construct( ILoadBalancer $loadBalancer ) {
+		parent::__construct( 'SubcatImagesGallery' );
+
+		$this->loadBalancer = $loadBalancer;
+	}
+
+	/**
+	 * @param string|null $param
+	 */
+	public function execute( $param ) {
+		$this->setHeaders();
+
+		$target = $param ? Title::makeTitleSafe( NS_CATEGORY, $param ) : null;
+		if ( !$target || !$target->exists() ) {
+			$out = $this->getOutput();
+			$out->setStatusCode( 404 );
+			$out->addWikiMsg( 'badtitletext' );
+			return;
+		}
+
+		$this->displayGallery( $target );
+	}
+
+	/**
+	 * Find all images in subcategories of $categoryTitle and output HTML of the resulting gallery.
+	 * @param Title $categoryTitle
+	 */
+	public function displayGallery( Title $categoryTitle ) {
+		$dbr = $this->loadBalancer->getConnection( DB_REPLICA );
+		$filenames = $dbr->newSelectQueryBuilder()
+			->select( [
+				'DISTINCT subcatpage.page_title'
+			] )
+			->from( 'categorylinks', 'topcat' )
+			->join( 'page', 'topcatpage', [
+				'topcatpage.page_id=topcat.cl_from',
+				'topcatpage.page_namespace' => NS_CATEGORY
+			] )
+			->join( 'categorylinks', 'subcat', [
+				'subcat.cl_to=topcatpage.page_title'
+			] )
+			->join( 'page', 'subcatpage', [
+				'subcatpage.page_id=subcat.cl_from',
+				'subcatpage.page_namespace' => NS_FILE
+			] )
+			->where( [
+				'topcat.cl_to' => $categoryTitle->getDbKey()
+			] )
+			->limit( $this->getConfig()->get( 'RelatedImagesMaxSubcatImages' ) )
+			->caller( __METHOD__ )
+			->fetchFieldValues();
+
+		$out = $this->getOutput();
+		if ( !$filenames ) {
+			$out->addWikiMsg( 'subcatimagesgallery-empty' );
+			return;
+		}
+
+		$gallery = ImageGalleryBase::factory( false, $this->getContext() );
+		$gallery->setHideBadImages( true );
+
+		foreach ( $filenames as $filename ) {
+			$title = Title::makeTitle( NS_FILE, $filename );
+			$gallery->add( $title );
+		}
+
+		$out->addHTML( $gallery->toHTML() );
+	}
+}