Adjust WebP generation for only certain JPEG sizes

src/wp-admin/includes/image.php

@@ -451,6 +451,9 @@ function _wp_make_subsizes( $new_sizes, $file, $image_meta, $attachment_id ) {
 
 	if ( method_exists( $editor, 'make_subsize' ) ) {
 		foreach ( $new_sizes as $new_size_name => $new_size_data ) {
+			// Include size name in the data.
+			$new_size_data['name'] = $new_size_name;
+
 			$new_size_meta = $editor->make_subsize( $new_size_data );
 
 			if ( is_wp_error( $new_size_meta ) ) {

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

@@ -227,7 +227,7 @@ protected function _resize( $max_w, $max_h, $crop = false ) {
 	 * @since 3.5.0
 	 *
 	 * @param array $sizes {
-	 *     An array of image size data arrays.
+	 *     Associative array of image size names and their data.
 	 *
 	 *     Either a height or width must be provided.
 	 *     If one of the two is set to null, the resize will
@@ -247,6 +247,9 @@ public function multi_resize( $sizes ) {
 		$metadata = array();
 
 		foreach ( $sizes as $size => $size_data ) {
+			// Include size name in the data.
+			$size_data['name'] = $size;
+
 			$meta = $this->make_subsize( $size_data );
 
 			if ( ! is_wp_error( $meta ) ) {
@@ -261,13 +264,15 @@ public function multi_resize( $sizes ) {
 	 * Create an image sub-size and return the image meta data value for it.
 	 *
 	 * @since 5.3.0
+	 * @since 6.1.0 The $sizes parameter may now include a $name key for each entry.
 	 *
 	 * @param array $size_data {
 	 *     Array of size data.
 	 *
-	 *     @type int  $width  The maximum width in pixels.
-	 *     @type int  $height The maximum height in pixels.
-	 *     @type bool $crop   Whether to crop the image to exact dimensions.
+	 *     @type int    $width  The maximum width in pixels.
+	 *     @type int    $height The maximum height in pixels.
+	 *     @type bool   $crop   Whether to crop the image to exact dimensions.
+	 *     @type string $name   Image size name.
 	 * }
 	 * @return array|WP_Error The image data array for inclusion in the `sizes` array in the image meta,
 	 *                        WP_Error object on error.
@@ -277,7 +282,8 @@ public function make_subsize( $size_data ) {
 			return new WP_Error( 'image_subsize_create_error', __( 'Cannot resize the image. Both width and height are not set.' ) );
 		}
 
-		$orig_size = $this->size;
+		$orig_size      = $this->size;
+		$orig_size_name = $this->size_name;
 
 		if ( ! isset( $size_data['width'] ) ) {
 			$size_data['width'] = null;
@@ -291,6 +297,10 @@ public function make_subsize( $size_data ) {
 			$size_data['crop'] = false;
 		}
 
+		if ( isset( $size_data['name'] ) ) {
+			$this->update_size_name( $size_data['name'] );
+		}
+
 		$resized = $this->_resize( $size_data['width'], $size_data['height'], $size_data['crop'] );
 
 		if ( is_wp_error( $resized ) ) {
@@ -301,6 +311,7 @@ public function make_subsize( $size_data ) {
 		}
 
 		$this->size = $orig_size;
+		$this->size_name = $orig_size_name;
 
 		if ( ! is_wp_error( $saved ) ) {
 			unset( $saved['path'] );

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

@@ -438,7 +438,7 @@ protected function thumbnail_image( $dst_w, $dst_h, $filter_name = 'FILTER_TRIAN
 	 * @since 3.5.0
 	 *
 	 * @param array $sizes {
-	 *     An array of image size data arrays.
+	 *     Associative array of image size names and their data.
 	 *
 	 *     Either a height or width must be provided.
 	 *     If one of the two is set to null, the resize will
@@ -458,6 +458,9 @@ public function multi_resize( $sizes ) {
 		$metadata = array();
 
 		foreach ( $sizes as $size => $size_data ) {
+			// Include size name in the data.
+			$size_data['name'] = $size;
+
 			$meta = $this->make_subsize( $size_data );
 
 			if ( ! is_wp_error( $meta ) ) {
@@ -472,13 +475,15 @@ public function multi_resize( $sizes ) {
 	 * Create an image sub-size and return the image meta data value for it.
 	 *
 	 * @since 5.3.0
+	 * @since 6.1.0 The $sizes parameter may now include a $name key for each entry.
 	 *
 	 * @param array $size_data {
 	 *     Array of size data.
 	 *
-	 *     @type int  $width  The maximum width in pixels.
-	 *     @type int  $height The maximum height in pixels.
-	 *     @type bool $crop   Whether to crop the image to exact dimensions.
+	 *     @type int    $width  The maximum width in pixels.
+	 *     @type int    $height The maximum height in pixels.
+	 *     @type bool   $crop   Whether to crop the image to exact dimensions.
+	 *     @type string $name   Image size name.
 	 * }
 	 * @return array|WP_Error The image data array for inclusion in the `sizes` array in the image meta,
 	 *                        WP_Error object on error.
@@ -488,8 +493,9 @@ public function make_subsize( $size_data ) {
 			return new WP_Error( 'image_subsize_create_error', __( 'Cannot resize the image. Both width and height are not set.' ) );
 		}
 
-		$orig_size  = $this->size;
-		$orig_image = $this->image->getImage();
+		$orig_size      = $this->size;
+		$orig_size_name = $this->size_name;
+		$orig_image     = $this->image->getImage();
 
 		if ( ! isset( $size_data['width'] ) ) {
 			$size_data['width'] = null;
@@ -503,6 +509,10 @@ public function make_subsize( $size_data ) {
 			$size_data['crop'] = false;
 		}
 
+		if ( isset( $size_data['name'] ) ) {
+			$this->update_size_name( $size_data['name'] );
+		}
+
 		$resized = $this->resize( $size_data['width'], $size_data['height'], $size_data['crop'] );
 
 		if ( is_wp_error( $resized ) ) {
@@ -515,8 +525,9 @@ public function make_subsize( $size_data ) {
 			$this->image = null;
 		}
 
-		$this->size  = $orig_size;
-		$this->image = $orig_image;
+		$this->size      = $orig_size;
+		$this->size_name = $orig_size_name;
+		$this->image     = $orig_image;
 
 		if ( ! is_wp_error( $saved ) ) {
 			unset( $saved['path'] );

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

@@ -14,6 +14,7 @@
 abstract class WP_Image_Editor {
 	protected $file              = null;
 	protected $size              = null;
+	protected $size_name         = '';
 	protected $mime_type         = null;
 	protected $output_mime_type  = null;
 	protected $default_mime_type = 'image/jpeg';
@@ -117,7 +118,7 @@ abstract public function resize( $max_w, $max_h, $crop = false );
 	 * @abstract
 	 *
 	 * @param array $sizes {
-	 *     An array of image size arrays. Default sizes are 'small', 'medium', 'large'.
+	 *     Associative array of image size names and their data. Default sizes are 'small', 'medium', 'large'.
 	 *
 	 *     @type array ...$0 {
 	 *         @type int  $width  Image width.
@@ -185,7 +186,7 @@ abstract public function stream( $mime_type = null );
 	 *
 	 * @since 3.5.0
 	 *
-	 * @return int[] {
+	 * @return array {
 	 *     Dimensions of the image.
 	 *
 	 *     @type int $width  The image width.
@@ -201,9 +202,9 @@ public function get_size() {
 	 *
 	 * @since 3.5.0
 	 *
-	 * @param int $width
-	 * @param int $height
-	 * @return true
+	 * @param int $width  The image width.
+	 * @param int $height The image height.
+	 * @return true True on success, false on failure.
 	 */
 	protected function update_size( $width = null, $height = null ) {
 		$this->size = array(
@@ -213,6 +214,28 @@ protected function update_size( $width = null, $height = null ) {
 		return true;
 	}
 
+	/**
+	 * Gets the current image size name.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @return string Image size name, or empty string if none set.
+	 */
+	public function get_size_name() {
+		return $this->size_name;
+	}
+
+	/**
+	 * Sets the current image size name.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param string $size_name The image size name.
+	 */
+	protected function update_size_name( $size_name ) {
+		$this->size_name = (string) $size_name;
+	}
+
 	/**
 	 * Gets the Image Compression quality on a 1-100% scale.
 	 *
@@ -364,6 +387,7 @@ protected function get_output_format( $filename = null, $mime_type = null ) {
 		 * @see WP_Image_Editor::get_output_format()
 		 *
 		 * @since 5.8.0
+		 * @since 6.1.0 The $size_name parameter was added.
 		 *
 		 * @param string[] $output_format {
 		 *     An array of mime type mappings. Maps a source mime type to a new
@@ -373,8 +397,9 @@ protected function get_output_format( $filename = null, $mime_type = null ) {
 		 * }
 		 * @param string $filename  Path to the image.
 		 * @param string $mime_type The source image mime type.
+		 * @param string $size_name The image size name to create, or empty string if not set.
 		 */
-		$output_format = apply_filters( 'image_editor_output_format', array(), $filename, $mime_type );
+		$output_format = apply_filters( 'image_editor_output_format', array(), $filename, $mime_type, $this->size_name );
 
 		if ( isset( $output_format[ $mime_type ] )
 			&& $this->supports_mime_type( $output_format[ $mime_type ] )

src/wp-includes/default-filters.php

@@ -632,7 +632,7 @@
 add_filter( 'image_send_to_editor', 'image_add_caption', 20, 8 );
 add_filter( 'media_send_to_editor', 'image_media_send_to_editor', 10, 3 );
 
-add_filter( 'image_editor_output_format', 'wp_default_image_output_mapping' );
+add_filter( 'image_editor_output_format', 'wp_default_image_output_mapping', 10, 4 );
 
 // Embeds.
 add_action( 'rest_api_init', 'wp_oembed_register_route' );

src/wp-includes/functions.php

@@ -2690,7 +2690,7 @@ function wp_unique_filename( $dir, $filename, $unique_filename_callback = null )
 		 */
 		if ( $is_image ) {
 			/** This filter is documented in wp-includes/class-wp-image-editor.php */
-			$output_formats = apply_filters( 'image_editor_output_format', array(), $_dir . $filename, $mime_type );
+			$output_formats = apply_filters( 'image_editor_output_format', array(), $_dir . $filename, $mime_type, '' );
 			$alt_types      = array();
 
 			if ( ! empty( $output_formats[ $mime_type ] ) ) {

src/wp-includes/media.php

@@ -3912,9 +3912,39 @@ function _wp_image_editor_choose( $args = array() ) {
  * @since 6.1.0
  *
  * @param array $output_mapping Map of mime type to output format.
- * @retun array The adjusted default output mapping.
+ * @param string $filename  Path to the image.
+ * @param string $mime_type The source image mime type.
+ * @param string $size_name Optional. The image size name to create, or empty string if not set. Default empty string.
+ * @return array The adjusted default output mapping.
  */
-function wp_default_image_output_mapping( $output_mapping ) {
+function wp_default_image_output_mapping( $output_mapping, $filename, $mime_type, $size_name = '' ) {
+	// If size name is specified, check whether the size supports additional MIME types like WebP.
+	if ( $size_name ) {
+		// Include only the core sizes that do not rely on add_image_size(). Additional image sizes are opt-in.
+		$enabled_sizes = array(
+			'thumbnail'      => true,
+			'medium'         => true,
+			'medium_large'   => true,
+			'large'          => true,
+			'post-thumbnail' => true,
+		);
+
+		/**
+		 * Filters the sizes that support secondary mime type output. Developers can use this
+		 * to control the generation of additional mime type sub-sized images.
+		 *
+		 * @since 6.1.0
+		 *
+		 * @param array $enabled_sizes Map of size names and whether they support secondary mime type output.
+		 */
+		$enabled_sizes = apply_filters( 'wp_image_sizes_with_additional_mime_type_support', $enabled_sizes );
+
+		// Bail early if the size does not support additional MIME types.
+		if ( empty( $enabled_sizes[ $size_name ] ) ) {
+			return $output_mapping;
+		}
+	}
+
 	$output_mapping['image/jpeg'] = 'image/webp';
 	return $output_mapping;
 }

tests/phpunit/tests/media.php

@@ -3626,7 +3626,7 @@ private function reset_omit_loading_attr_filter() {
 	 * @ticket 55443
 	 */
 	public function test_wp_default_image_output_mapping() {
-		$mapping = wp_default_image_output_mapping( array() );
+		$mapping = wp_default_image_output_mapping( array(), 'test.jpg', 'image/jpeg', '' );
 		$this->assertSame( array( 'image/jpeg' => 'image/webp' ), $mapping );
 	}
 
@@ -3637,7 +3637,7 @@ public function test_wp_default_image_output_mapping() {
 	 */
 	public function test_wp_default_image_output_mapping_existing() {
 		$mapping = array( 'mime/png' => 'mime/webp' );
-		$mapping = wp_default_image_output_mapping( $mapping );
+		$mapping = wp_default_image_output_mapping( $mapping, 'test.jpg', 'image/jpeg', '' );
 		$this->assertSame(
 			array(
 				'mime/png'   => 'mime/webp',
@@ -3672,6 +3672,78 @@ public function test_wp_image_editor_default_output_maps_to_webp() {
 			$this->assertSame( 'canola-100x75.jpg', $saved['file'] );
 		}
 	}
+
+	/**
+	 * @ticket 56526
+	 * @dataProvider data_wp_default_image_output_mapping_size_filter
+	 */
+	public function test_wp_default_image_output_mapping_size_filter( $size_name, $filter_callback, $expects_webp ) {
+		remove_all_filters( 'wp_image_sizes_with_additional_mime_type_support' );
+		if ( $filter_callback ) {
+			add_filter( 'wp_image_sizes_with_additional_mime_type_support', $filter_callback );
+		}
+
+		$mapping = wp_default_image_output_mapping( array(), 'test.jpg', 'image/jpeg', $size_name );
+		if ( $expects_webp ) {
+			$this->assertSame( array( 'image/jpeg' => 'image/webp' ), $mapping );
+		} else {
+			$this->assertSame( array(), $mapping );
+		}
+	}
+
+	public function data_wp_default_image_output_mapping_size_filter() {
+		return array(
+			'default size thumbnail'    => array(
+				'thumbnail',
+				null,
+				true,
+			),
+			'default size medium'       => array(
+				'medium',
+				null,
+				true,
+			),
+			'default size medium_large' => array(
+				'medium_large',
+				null,
+				true,
+			),
+			'default size large'        => array(
+				'large',
+				null,
+				true,
+			),
+			'default size unset'        => array(
+				'medium',
+				function( $enabled_sizes ) {
+					unset( $enabled_sizes['medium'] );
+					return $enabled_sizes;
+				},
+				false,
+			),
+			'default size set to false' => array(
+				'medium',
+				function( $enabled_sizes ) {
+					$enabled_sizes['medium'] = false;
+					return $enabled_sizes;
+				},
+				false,
+			),
+			'custom size'               => array(
+				'custom',
+				null,
+				false,
+			),
+			'custom size opted in'      => array(
+				'custom',
+				function( $enabled_sizes ) {
+					$enabled_sizes['custom'] = true;
+					return $enabled_sizes;
+				},
+				true,
+			),
+		);
+	}
 }
 
 /**