[not verified] Refactor post list thumbnail preview to function serve…

…r side. All javascript removed. (#21126)

* Reworking post-list thumbnails to be server side.

* Added changelog file.

* Added CSS and placeholder image for empty thumbnails.

* CSS fix placeholder disappearing.

* Updated unit tests. Added alt tag to thumbnail image.

* Updated comments.

* Added rtl.css.

* Don't add thumbnail column if 'title' is missing for some reason.

* Add thumbnails to "Pages" admin table. Removed unused class name from thumbnail img.

* Created add_thumbnail_filters_and_actions and moved column filter and action out of enqueue_scripts and into current_screen.

* Removed unused in_admin_footer action.

projects/packages/post-list/changelog/refactor-server-side

@@ -0,0 +1,3 @@
+Significance: patch
+Type: changed
+Comment: Refactored to function server side. All javascript removed.

projects/packages/post-list/src/class-post-list.php

@@ -7,8 +7,6 @@
 
 namespace Automattic\Jetpack\Post_List;
 
-use Automattic\Jetpack\Assets;
-
 /**
  * The Post_List Admin Area
  */
@@ -34,13 +32,12 @@ public static function get_instance() {
 	}
 
 	/**
-	 * Sets up Post List action callbacks if needed.
+	 * Sets up Post List action callbacks.
 	 */
 	public function register() {
 		if ( ! did_action( 'jetpack_on_posts_list_init' ) ) {
 			add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
-			add_action( 'in_admin_footer', array( $this, 'create_app_root_element' ) );
-
+			add_action( 'current_screen', array( $this, 'add_thumbnail_filters_and_actions' ) );
 			add_filter( 'default_hidden_columns', array( $this, 'adjust_default_columns' ), 10, 2 );
 
 			/**
@@ -53,72 +50,80 @@ public function register() {
 	}
 
 	/**
-	 * Enqueue scripts depending on the post-list query var.
+	 * Enqueue scripts.
 	 *
 	 * @param string $hook Page hook.
 	 */
 	public function enqueue_scripts( $hook ) {
 		if ( 'edit.php' === $hook ) {
-			$plugin_path = Assets::get_file_url_for_environment( './index.js', './index.js', __FILE__ );
-
-			wp_enqueue_script(
-				'jetpack_posts_list_ui_script',
-				$plugin_path,
-				array(),
-				self::PACKAGE_VERSION,
-				true
-			);
-
 			wp_enqueue_style(
 				'jetpack_posts_list_ui_style',
 				plugin_dir_url( __DIR__ ) . './src/style.css',
 				array(),
 				self::PACKAGE_VERSION
 			);
-
 			wp_style_add_data(
 				'jetpack_posts_list_ui_style',
 				'rtl',
-				plugin_dir_url( __DIR__ ) . 'build/style.rtl.css'
+				plugin_dir_url( __DIR__ ) . './src/rtl.css'
 			);
-
-			wp_set_script_translations( 'jetpack_posts_list_ui_script', 'jetpack' );
-
-			add_action( 'admin_footer', array( $this, 'print_post_data' ) );
 		}
 	}
 
 	/**
-	 * Outputs a JSON blob to the global `wp_admin_posts` variable, for use
-	 * by the JS application
+	 * If the current_screen has 'edit' as the base, add filters and actions to add the thumbnail column to the Posts
+	 * and Pages admin tables.
+	 *
+	 * @param object $current_screen The current screen.
 	 */
-	public function print_post_data() {
-		global $wp_query;
+	public function add_thumbnail_filters_and_actions( $current_screen ) {
+		if ( 'edit' === $current_screen->base ) {
+			// Add the thumbnail column to the "Posts" admin table.
+			add_filter( 'manage_posts_columns', array( $this, 'add_thumbnail_column' ) );
+			add_action( 'manage_posts_custom_column', array( $this, 'populate_thumbnail_rows' ), 10, 2 );
+
+			// Add the thumbnail column to the "Pages" admin table.
+			add_filter( 'manage_pages_columns', array( $this, 'add_thumbnail_column' ) );
+			add_action( 'manage_pages_custom_column', array( $this, 'populate_thumbnail_rows' ), 10, 2 );
+		}
+	}
 
-		if ( ! post_type_supports( $wp_query->query['post_type'], 'thumbnail' ) ) {
-			return;
+	/**
+	 * Adds a new column header for displaying the thumbnail of a post.
+	 *
+	 * @param array $columns An array of column names.
+	 * @return array An array of column names.
+	 */
+	public function add_thumbnail_column( $columns ) {
+		$new_column = array( 'thumbnail' => '<span>' . __( 'Thumbnail', 'jetpack' ) . '</span>' );
+		$keys       = array_keys( $columns );
+		$position   = array_search( 'title', $keys, true );
+
+		// If 'title' not found, don't insert the thumbnail column.
+		if ( false !== $position ) {
+			$columns = array_merge( array_slice( $columns, 0, $position ), $new_column, array_slice( $columns, $position ) );
 		}
 
-		$post_data = array_map(
-			function ( $post ) {
-				$thumbnail = Post_Thumbnail::get_post_thumbnail( $post );
-				return array(
-					'id'             => $post->ID,
-					'type'           => $post->post_type,
-					'featured_image' => $thumbnail,
-				);
-			},
-			$wp_query->posts
-		);
-		wp_add_inline_script( 'jetpack_posts_list_ui_script', 'var wpAdminPosts = ' . wp_json_encode( $post_data ) );
+		return $columns;
 	}
 
 	/**
-	 * Add a placeholder element for the
-	 * to mount the client app (root element).
+	 * Displays the thumbnail content.
+	 *
+	 * @param string $column  The name of the column to display.
+	 * @param int    $post_id The current post ID.
 	 */
-	public function create_app_root_element() {
-		echo '<div id="wp-post-list-app" style="display: none;"></div>';
+	public function populate_thumbnail_rows( $column, $post_id ) {
+		if ( 'thumbnail' !== $column ) {
+			return;
+		}
+
+		$thumbnail = Post_Thumbnail::get_post_thumbnail( get_post( $post_id ) );
+		if ( $thumbnail ) {
+			echo '<img src="' . esc_url( $thumbnail['thumb'] ) . '" alt="' . esc_attr( $thumbnail['alt'] ) . '" height="50" width="50" />';
+		} else {
+			echo '<span class="dashicons dashicons-format-image" title="No thumbnail found."></span>';
+		}
 	}
 
 	/**

projects/packages/post-list/src/class-post-thumbnail.php

@@ -16,7 +16,7 @@ class Post_Thumbnail {
 	 * neither exists returns the image array with null values.
 	 *
 	 * @param object $post The current post.
-	 * @return array The thumbnail image id and URLs
+	 * @return array|null The thumbnail image id and URLs
 	 */
 	public static function get_post_thumbnail( $post ) {
 		$image_id    = null;
@@ -31,7 +31,7 @@ public static function get_post_thumbnail( $post ) {
 			$image_id    = get_post_thumbnail_id( $post_id );
 			$image_url   = get_the_post_thumbnail_url( $post_id );
 			$image_thumb = get_the_post_thumbnail_url( $post_id, array( 50, 50 ) );
-			$image_alt   = get_post_meta( $post_id, '_wp_attachment_image_alt', true );
+			$image_alt   = get_post_meta( $image_id, '_wp_attachment_image_alt', true );
 		} else {
 			// If a featured image does not exist look for the first "media library" hosted image on the post.
 			$attachment_id = self::get_first_image_id_from_post_content( $post->post_content );
@@ -44,6 +44,11 @@ public static function get_post_thumbnail( $post ) {
 			}
 		}
 
+		// If no thumbnail is found return null.
+		if ( null === $image_thumb ) {
+			return null;
+		}
+
 		// Escape values just in case.
 		return array(
 			'id'    => esc_attr( $image_id ),

projects/packages/post-list/src/rtl.css

@@ -0,0 +1,9 @@
+/* Pull "Title" header name over in "Thumbnail"s place. */
+th.column-thumbnail + th a {
+	margin-right:-60px;
+}
+
+/* If thumbnail column has .hidden class. The entire column is toggled off. Don't pull "Title" header name over. */
+th.column-thumbnail.hidden + th a {
+	margin-right:0;
+}

projects/packages/post-list/src/style.css

@@ -1,16 +1,46 @@
+/* Set the width of the thumbnail column */
+.column-thumbnail {
+	width: 50px;
+}
 
-.post-featured-image__container {
-	float: left;
-	margin-right: 5px;
+/* Style the thumbnail image. */
+.column-thumbnail img {
+	width: 50px;
+	height: 50px;
+	border-radius: 4px;
 }
 
-.post-featured-image__container	.post-list__post-featured-image {
-	width: 48px;
-	height: 48px;
-	fill: #ccc;
+/* Style the Dashicon placeholder for empty thumbnails. */
+.column-thumbnail .dashicons {
+	font-size: 50px;
+	width: 50px;
+	height: 50px;
+	background: #c3c4c7;
 	border-radius: 4px;
+	color: #f6f7f7;
+}
+
+/* Keep data-colname from appearing on mobile view. */
+.column-thumbnail::before {
+	content: "" !important;
+}
+
+/* Move the "Thumbnail" and "Title" columns closer together. */
+th.column-thumbnail {
+	padding-right:0;
+}
+
+/* Don't display the "Thumbnail" column name in the header or footer. */
+th.column-thumbnail span {
+	display:none;
+}
+
+/* Pull "Title" header name over in "Thumbnail"s place. */
+th.column-thumbnail + th a {
+	margin-left:-60px;
 }
 
-.post-list__post-featured-image .components-popover__content {
-	padding: 5px;
+/* If thumbnail column has .hidden class. The entire column is toggled off. Don't pull "Title" header name over. */
+th.column-thumbnail.hidden + th a {
+	margin-left:0;
 }

projects/packages/post-list/tests/php/bootstrap.php

@@ -6,7 +6,7 @@
  */
 
 /**
- * Composer's autoloader is all we need.
+ * Composer's autoloader.
  */
 require_once __DIR__ . '/../../vendor/autoload.php';