From 8c32946ca1f54e98a138cc4b4bbce4ff69d10f3b Mon Sep 17 00:00:00 2001
From: Matthias Mullie <git@mullie.eu>
Date: Mon, 18 Jul 2016 14:52:08 +0200
Subject: [PATCH] Exclude duplicate srcset urls

Bug: T135550
Change-Id: I956dc155426739d60052a0dc77dafdf0414d5bd7
---
 includes/Html.php                       | 16 ++++++++++++++--
 includes/media/MediaTransformOutput.php |  6 ++++--
 tests/parser/parserTests.txt            | 14 ++++++++++++++
 tests/phpunit/includes/HtmlTest.php     | 10 ++++++++++
 4 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/includes/Html.php b/includes/Html.php
index e5128d166c..a5567fc043 100644
--- a/includes/Html.php
+++ b/includes/Html.php
@@ -1020,9 +1020,21 @@ class Html {
 	static function srcSet( array $urls ) {
 		$candidates = [];
 		foreach ( $urls as $density => $url ) {
-			// Cast density to float to strip 'x'.
-			$candidates[] = $url . ' ' . (float)$density . 'x';
+			// Cast density to float to strip 'x', then back to string to serve
+			// as array index.
+			$density = (string)(float)$density;
+			$candidates[$density] = $url;
 		}
+
+		// Remove duplicates that are the same as a smaller value
+		ksort( $candidates, SORT_NUMERIC );
+		$candidates = array_unique( $candidates );
+
+		// Append density info to the url
+		foreach ( $candidates as $density => $url ) {
+			$candidates[$density] = $url . ' ' . $density . 'x';
+		}
+
 		return implode( ", ", $candidates );
 	}
 }
diff --git a/includes/media/MediaTransformOutput.php b/includes/media/MediaTransformOutput.php
index 9176b54666..b3a555aa5c 100644
--- a/includes/media/MediaTransformOutput.php
+++ b/includes/media/MediaTransformOutput.php
@@ -421,8 +421,10 @@ class ThumbnailImage extends MediaTransformOutput {
 		}
 
 		// Additional densities for responsive images, if specified.
-		if ( !empty( $this->responsiveUrls ) ) {
-			$attribs['srcset'] = Html::srcSet( $this->responsiveUrls );
+		// If any of these urls is the same as src url, it'll be excluded.
+		$responsiveUrls = array_diff( $this->responsiveUrls, [ $this->url ] );
+		if ( !empty( $responsiveUrls ) ) {
+			$attribs['srcset'] = Html::srcSet( $responsiveUrls );
 		}
 
 		Hooks::run( 'ThumbnailBeforeProduceHTML', [ $this, &$attribs, &$linkAttribs ] );
diff --git a/tests/parser/parserTests.txt b/tests/parser/parserTests.txt
index dd506074bc..4c853b11b4 100644
--- a/tests/parser/parserTests.txt
+++ b/tests/parser/parserTests.txt
@@ -27080,3 +27080,17 @@ Empty LI (T49673)
 <li>b</li>
 </ul>
 !! end
+
+!! test
+Thumbnail output
+!! wikitext
+[[File:Thumb.png|thumb]]
+!! html/php+tidy
+<div class="thumb tright">
+<div class="thumbinner" style="width:137px;"><a href="/wiki/File:Thumb.png" class="image"><img alt="Thumb.png" src="http://example.com/images/e/ea/Thumb.png" width="135" height="135" class="thumbimage" /></a>
+<div class="thumbcaption">
+<div class="magnify"><a href="/wiki/File:Thumb.png" class="internal" title="Enlarge"></a></div>
+</div>
+</div>
+</div>
+!! end
diff --git a/tests/phpunit/includes/HtmlTest.php b/tests/phpunit/includes/HtmlTest.php
index 47217939bf..e44db83b44 100644
--- a/tests/phpunit/includes/HtmlTest.php
+++ b/tests/phpunit/includes/HtmlTest.php
@@ -738,6 +738,16 @@ class HtmlTest extends MediaWikiTestCase {
 				'1x.png 1x, 1_5x.png 1.5x, 2x.png 2x',
 				'pixel depth keys may omit a trailing "x"'
 			],
+			[
+				[ '1'  => 'small.png', '1.5' => 'large.png', '2'  => 'large.png' ],
+				'small.png 1x, large.png 1.5x',
+				'omit larger duplicates'
+			],
+			[
+				[ '1'  => 'small.png', '2'  => 'large.png', '1.5' => 'large.png' ],
+				'small.png 1x, large.png 1.5x',
+				'omit larger duplicates in irregular order'
+			],
 		];
 	}
 
-- 
2.20.1