feat: Allow to configure what dpi factors to generated in the thumbnail srcset attribute.

Author: das-peter

bundles/CoreBundle/DependencyInjection/Configuration.php

@@ -563,6 +563,17 @@ private function addAssetNode(ArrayNodeDefinition $rootNode)
                                         ->end()
                                         ->defaultTrue()
                                     ->end()
+                                    ->integerNode('max_srcset_dpi_factor')
+                                        ->info('Maximum generated srcset DPI factor for web images.')
+                                        ->addDefaultsIfNotSet()
+                                        ->beforeNormalization()
+                                            ->ifString()
+                                            ->then(function ($v) {
+                                                return (int)$v;
+                                            })
+                                        ->end()
+                                        ->defaultValue(2)
+                                    ->end()
                                     ->arrayNode('image_optimizers')
                                         ->addDefaultsIfNotSet()
                                         ->canBeDisabled()

models/Asset/Image/Thumbnail.php

@@ -471,7 +471,8 @@ private function createConfig($selector)
     private function getSrcset(Config $thumbConfig, Image $image, array $options, ?string $mediaQuery = null): string
     {
         $srcSetValues = [];
-        foreach ([1, 2] as $highRes) {
+        $maxDpiFactor = $thumbConfig::getMaxDpiFactor();
+        for ($highRes=1; $highRes <= $maxDpiFactor; $highRes++) {
             $thumbConfigRes = clone $thumbConfig;
             if ($mediaQuery) {
                 $thumbConfigRes->selectMedia($mediaQuery);

models/Asset/Image/Thumbnail/Config.php

@@ -973,4 +973,14 @@ public function generateAutoName(): void
 
         $this->setName($this->getName() . '_auto_' . md5($serialized));
     }
+
+    /**
+     * @internal
+     *
+     * @return integer
+     */
+    public static function getMaxDpiFactor(): int
+    {
+        return \Pimcore::getContainer()->getParameter('pimcore.config')['assets']['image']['thumbnails']['max_srcset_dpi_factor'];
+    }
 }