Media: improve support for lossless WebP.

When uploading lossless WebP images, WordPress now correctly outputs lossless WebP with both the Imagick and GD image editors.

Props: adamsilverstein, martinkrcho.
Fixes #60291.



git-svn-id: https://develop.svn.wordpress.org/trunk@59145 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-image-editor-gd.php

@@ -571,6 +571,38 @@ protected function _save( $image, $filename = null, $mime_type = null ) {
 		);
 	}
 
+	/**
+	 * Sets Image Compression quality on a 1-100% scale. Handles WebP lossless images.
+	 *
+	 * @since 6.7.0
+	 *
+	 * @param int $quality Compression Quality. Range: [1,100]
+	 * @return true|WP_Error True if set successfully; WP_Error on failure.
+	 */
+	public function set_quality( $quality = null ) {
+		$quality_result = parent::set_quality( $quality );
+		if ( is_wp_error( $quality_result ) ) {
+			return $quality_result;
+		} else {
+			$quality = $this->get_quality();
+		}
+
+		// Handle setting the quality for WebP lossless images, see https://php.watch/versions/8.1/gd-webp-lossless.
+		try {
+			if ( 'image/webp' === $this->mime_type && defined( 'IMG_WEBP_LOSSLESS' ) ) {
+				$webp_info = wp_get_webp_info( $this->file );
+				if ( ! empty( $webp_info['type'] ) && 'lossless' === $webp_info['type'] ) {
+					$quality = IMG_WEBP_LOSSLESS;
+					parent::set_quality( $quality );
+				}
+			}
+		} catch ( Exception $e ) {
+			return new WP_Error( 'image_quality_error', $e->getMessage() );
+		}
+		$this->quality = $quality;
+		return true;
+	}
+
 	/**
 	 * Returns stream of current image.
 	 *

src/wp-includes/class-wp-image-editor-imagick.php

@@ -215,6 +215,7 @@ public function set_quality( $quality = null ) {
 						// Use WebP lossless settings.
 						$this->image->setImageCompressionQuality( 100 );
 						$this->image->setOption( 'webp:lossless', 'true' );
+						parent::set_quality( 100 );
 					} else {
 						$this->image->setImageCompressionQuality( $quality );
 					}

tests/phpunit/tests/media.php

@@ -6103,6 +6103,34 @@ static function ( $loading_attrs ) {
 		);
 	}
 
+
+	/**
+	 * Test WebP lossless quality is handled correctly.
+	 *
+	 * @ticket 60291
+	 */
+	public function test_set_quality_webp_lossless() {
+		// Get a new editor to test that lossless WebP images are handled correctly.
+		$editor = wp_get_image_editor( DIR_TESTDATA . '/images/webp-lossless.webp' );
+
+		// If no editor is available, skip the test.
+		if ( is_wp_error( $editor ) ) {
+			$this->markTestSkipped( 'No editor available for lossless WebP images.' );
+		}
+
+		// Only test on GD when WebP lossless is supported.
+		if ( 'WP_Image_Editor_GD' === get_class( $editor ) && ! defined( 'IMG_WEBP_LOSSLESS' ) ) {
+			$this->markTestSkipped( 'No GD support available for lossless WebP images.' );
+		}
+
+		// Verify lossless quality is set correctly: IMG_WEBP_LOSSLESS for GD and 100 for Imagick.
+		if ( 'WP_Image_Editor_GD' === get_class( $editor ) ) {
+			$this->assertSame( IMG_WEBP_LOSSLESS, $editor->get_quality() );
+		} else {
+			$this->assertSame( 100, $editor->get_quality() );
+		}
+	}
+
 	/**
 	 * Test generated markup for an image with lazy loading gets auto-sizes.
 	 *