name : post-thumbnail-template.php <?php /** * WordPress Post Thumbnail Template Functions. * * Support for post thumbnails. * Theme's functions.php must call add_theme_support( 'post-thumbnails' ) to use these. * * @package WordPress * @subpackage Template */ /** * Check if post has an image attached. * * @since 2.9.0 * @since 4.4.0 `$post` can be a post ID or WP_Post object. * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. * @return bool Whether the post has an image attached. */ function has_post_thumbnail( $post = null ) { return (bool) get_post_thumbnail_id( $post ); } /** * Retrieve post thumbnail ID. * * @since 2.9.0 * @since 4.4.0 `$post` can be a post ID or WP_Post object. * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. * @return string|int Post thumbnail ID or empty string. */ function get_post_thumbnail_id( $post = null ) { $post = get_post( $post ); if ( ! $post ) { return ''; } return get_post_meta( $post->ID, '_thumbnail_id', true ); } /** * Display the post thumbnail. * * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size * is registered, which differs from the 'thumbnail' image size managed via the * Settings > Media screen. * * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image * size is used by default, though a different size can be specified instead as needed. * * @since 2.9.0 * * @see get_the_post_thumbnail() * * @param string|array $size Optional. Image size to use. Accepts any valid image size, or * an array of width and height values in pixels (in that order). * Default 'post-thumbnail'. * @param string|array $attr Optional. Query string or array of attributes. Default empty. */ function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) { echo get_the_post_thumbnail( null, $size, $attr ); } /** * Update cache for thumbnails in the current loop. * * @since 3.2.0 * * @global WP_Query $wp_query * * @param WP_Query $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global. */ function update_post_thumbnail_cache( $wp_query = null ) { if ( ! $wp_query ) $wp_query = $GLOBALS['wp_query']; if ( $wp_query->thumbnails_cached ) return; $thumb_ids = array(); foreach ( $wp_query->posts as $post ) { if ( $id = get_post_thumbnail_id( $post->ID ) ) $thumb_ids[] = $id; } if ( ! empty ( $thumb_ids ) ) { _prime_post_caches( $thumb_ids, false, true ); } $wp_query->thumbnails_cached = true; } /** * Retrieve the post thumbnail. * * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size * is registered, which differs from the 'thumbnail' image size managed via the * Settings > Media screen. * * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image * size is used by default, though a different size can be specified instead as needed. * * @since 2.9.0 * @since 4.4.0 `$post` can be a post ID or WP_Post object. * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. * @param string|array $size Optional. Image size to use. Accepts any valid image size, or * an array of width and height values in pixels (in that order). * Default 'post-thumbnail'. * @param string|array $attr Optional. Query string or array of attributes. Default empty. * @return string The post thumbnail image tag. */ function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr = '' ) { $post = get_post( $post ); if ( ! $post ) { return ''; } $post_thumbnail_id = get_post_thumbnail_id( $post ); /** * Filters the post thumbnail size. * * @since 2.9.0 * @since 4.9.0 Added the `$post_id` parameter. * * @param string|array $size The post thumbnail size. Image size or array of width and height * values (in that order). Default 'post-thumbnail'. * @param int $post_id The post ID. */ $size = apply_filters( 'post_thumbnail_size', $size, $post->ID ); if ( $post_thumbnail_id ) { /** * Fires before fetching the post thumbnail HTML. * * Provides "just in time" filtering of all filters in wp_get_attachment_image(). * * @since 2.9.0 * * @param int $post_id The post ID. * @param string $post_thumbnail_id The post thumbnail ID. * @param string|array $size The post thumbnail size. Image size or array of width * and height values (in that order). Default 'post-thumbnail'. */ do_action( 'begin_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size ); if ( in_the_loop() ) update_post_thumbnail_cache(); $html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr ); /** * Fires after fetching the post thumbnail HTML. * * @since 2.9.0 * * @param int $post_id The post ID. * @param string $post_thumbnail_id The post thumbnail ID. * @param string|array $size The post thumbnail size. Image size or array of width * and height values (in that order). Default 'post-thumbnail'. */ do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size ); } else { $html = ''; } /** * Filters the post thumbnail HTML. * * @since 2.9.0 * * @param string $html The post thumbnail HTML. * @param int $post_id The post ID. * @param string $post_thumbnail_id The post thumbnail ID. * @param string|array $size The post thumbnail size. Image size or array of width and height * values (in that order). Default 'post-thumbnail'. * @param string $attr Query string of attributes. */ return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr ); } /** * Return the post thumbnail URL. * * @since 4.4.0 * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. * @param string|array $size Optional. Registered image size to retrieve the source for or a flat * array of height and width dimensions. Default 'post-thumbnail'. * @return string|false Post thumbnail URL or false if no URL is available. */ function get_the_post_thumbnail_url( $post = null, $size = 'post-thumbnail' ) { $post_thumbnail_id = get_post_thumbnail_id( $post ); if ( ! $post_thumbnail_id ) { return false; } return wp_get_attachment_image_url( $post_thumbnail_id, $size ); } /** * Display the post thumbnail URL. * * @since 4.4.0 * * @param string|array $size Optional. Image size to use. Accepts any valid image size, * or an array of width and height values in pixels (in that order). * Default 'post-thumbnail'. */ function the_post_thumbnail_url( $size = 'post-thumbnail' ) { $url = get_the_post_thumbnail_url( null, $size ); if ( $url ) { echo esc_url( $url ); } } /** * Returns the post thumbnail caption. * * @since 4.6.0 * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. * @return string Post thumbnail caption. */ function get_the_post_thumbnail_caption( $post = null ) { $post_thumbnail_id = get_post_thumbnail_id( $post ); if ( ! $post_thumbnail_id ) { return ''; } $caption = wp_get_attachment_caption( $post_thumbnail_id ); if ( ! $caption ) { $caption = ''; } return $caption; } /** * Displays the post thumbnail caption. * * @since 4.6.0 * * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`. */ function the_post_thumbnail_caption( $post = null ) { /** * Filters the displayed post thumbnail caption. * * @since 4.6.0 * * @param string $caption Caption for the given attachment. */ echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) ); }