330 lines
11 KiB
PHP
330 lines
11 KiB
PHP
<?php
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/**
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* WordPress Post Thumbnail Template Functions.
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*
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* Support for post thumbnails.
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* Theme's functions.php must call add_theme_support( 'post-thumbnails' ) to use these.
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*
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* @package WordPress
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* @subpackage Template
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*/
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/**
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* Determines whether a post has an image attached.
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*
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* For more information on this and similar theme functions, check out
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* the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
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* Conditional Tags} article in the Theme Developer Handbook.
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*
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* @since 2.9.0
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* @since 4.4.0 `$post` can be a post ID or WP_Post object.
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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* @return bool Whether the post has an image attached.
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*/
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function has_post_thumbnail( $post = null ) {
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$thumbnail_id = get_post_thumbnail_id( $post );
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$has_thumbnail = (bool) $thumbnail_id;
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/**
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* Filters whether a post has a post thumbnail.
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*
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* @since 5.1.0
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*
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* @param bool $has_thumbnail true if the post has a post thumbnail, otherwise false.
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* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
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* @param int|false $thumbnail_id Post thumbnail ID or false if the post does not exist.
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*/
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return (bool) apply_filters( 'has_post_thumbnail', $has_thumbnail, $post, $thumbnail_id );
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}
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/**
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* Retrieves the post thumbnail ID.
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*
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* @since 2.9.0
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* @since 4.4.0 `$post` can be a post ID or WP_Post object.
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* @since 5.5.0 The return value for a non-existing post
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* was changed to false instead of an empty string.
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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* @return int|false Post thumbnail ID (which can be 0 if the thumbnail is not set),
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* or false if the post does not exist.
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*/
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function get_post_thumbnail_id( $post = null ) {
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$post = get_post( $post );
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if ( ! $post ) {
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return false;
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}
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$thumbnail_id = (int) get_post_meta( $post->ID, '_thumbnail_id', true );
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/**
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* Filters the post thumbnail ID.
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*
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* @since 5.9.0
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*
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* @param int|false $thumbnail_id Post thumbnail ID or false if the post does not exist.
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* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
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*/
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return (int) apply_filters( 'post_thumbnail_id', $thumbnail_id, $post );
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}
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/**
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* Displays the post thumbnail.
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*
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* When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
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* is registered, which differs from the 'thumbnail' image size managed via the
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* Settings > Media screen.
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*
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* When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
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* size is used by default, though a different size can be specified instead as needed.
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*
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* @since 2.9.0
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*
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* @see get_the_post_thumbnail()
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*
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* @param string|int[] $size Optional. Image size. Accepts any registered image size name, or an array of
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* width and height values in pixels (in that order). Default 'post-thumbnail'.
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* @param string|array $attr Optional. Query string or array of attributes. Default empty.
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*/
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function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
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echo get_the_post_thumbnail( null, $size, $attr );
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}
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/**
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* Updates cache for thumbnails in the current loop.
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*
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* @since 3.2.0
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*
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* @global WP_Query $wp_query WordPress Query object.
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*
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* @param WP_Query $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.
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*/
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function update_post_thumbnail_cache( $wp_query = null ) {
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if ( ! $wp_query ) {
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$wp_query = $GLOBALS['wp_query'];
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}
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if ( $wp_query->thumbnails_cached ) {
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return;
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}
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$thumb_ids = array();
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/*
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* $wp_query may contain an array of post objects or post IDs.
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*
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* This ensures the cache is primed for all post objects to avoid
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* `get_post()` calls in `get_the_post_thumbnail()` triggering an
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* additional database call for each post.
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*/
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$parent_post_ids = array();
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foreach ( $wp_query->posts as $post ) {
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if ( $post instanceof WP_Post ) {
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$parent_post_ids[] = $post->ID;
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} elseif ( is_int( $post ) ) {
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$parent_post_ids[] = $post;
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}
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}
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_prime_post_caches( $parent_post_ids, false, true );
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foreach ( $wp_query->posts as $post ) {
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$id = get_post_thumbnail_id( $post );
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if ( $id ) {
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$thumb_ids[] = $id;
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}
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}
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if ( ! empty( $thumb_ids ) ) {
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_prime_post_caches( $thumb_ids, false, true );
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}
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$wp_query->thumbnails_cached = true;
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}
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/**
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* Retrieves the post thumbnail.
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*
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* When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
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* is registered, which differs from the 'thumbnail' image size managed via the
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* Settings > Media screen.
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*
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* When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
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* size is used by default, though a different size can be specified instead as needed.
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*
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* @since 2.9.0
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* @since 4.4.0 `$post` can be a post ID or WP_Post object.
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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* @param string|int[] $size Optional. Image size. Accepts any registered image size name, or an array of
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* width and height values in pixels (in that order). Default 'post-thumbnail'.
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* @param string|array $attr Optional. Query string or array of attributes. Default empty.
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* @return string The post thumbnail image tag.
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*/
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function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr = '' ) {
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$post = get_post( $post );
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if ( ! $post ) {
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return '';
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}
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$post_thumbnail_id = get_post_thumbnail_id( $post );
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/**
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* Filters the post thumbnail size.
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*
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* @since 2.9.0
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* @since 4.9.0 Added the `$post_id` parameter.
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*
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* @param string|int[] $size Requested image size. Can be any registered image size name, or
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* an array of width and height values in pixels (in that order).
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* @param int $post_id The post ID.
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*/
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$size = apply_filters( 'post_thumbnail_size', $size, $post->ID );
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if ( $post_thumbnail_id ) {
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/**
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* Fires before fetching the post thumbnail HTML.
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*
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* Provides "just in time" filtering of all filters in wp_get_attachment_image().
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*
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* @since 2.9.0
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*
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* @param int $post_id The post ID.
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* @param int $post_thumbnail_id The post thumbnail ID.
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* @param string|int[] $size Requested image size. Can be any registered image size name, or
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* an array of width and height values in pixels (in that order).
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*/
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do_action( 'begin_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );
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if ( in_the_loop() ) {
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update_post_thumbnail_cache();
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}
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$html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );
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/**
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* Fires after fetching the post thumbnail HTML.
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*
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* @since 2.9.0
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*
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* @param int $post_id The post ID.
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* @param int $post_thumbnail_id The post thumbnail ID.
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* @param string|int[] $size Requested image size. Can be any registered image size name, or
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* an array of width and height values in pixels (in that order).
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*/
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do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );
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} else {
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$html = '';
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}
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/**
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* Filters the post thumbnail HTML.
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*
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* @since 2.9.0
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*
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* @param string $html The post thumbnail HTML.
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* @param int $post_id The post ID.
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* @param int $post_thumbnail_id The post thumbnail ID, or 0 if there isn't one.
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* @param string|int[] $size Requested image size. Can be any registered image size name, or
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* an array of width and height values in pixels (in that order).
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* @param string|array $attr Query string or array of attributes.
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*/
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return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
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}
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/**
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* Returns the post thumbnail URL.
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*
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* @since 4.4.0
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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* @param string|int[] $size Optional. Registered image size to retrieve the source for or a flat array
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* of height and width dimensions. Default 'post-thumbnail'.
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* @return string|false Post thumbnail URL or false if no image is available. If `$size` does not match
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* any registered image size, the original image URL will be returned.
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*/
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function get_the_post_thumbnail_url( $post = null, $size = 'post-thumbnail' ) {
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$post_thumbnail_id = get_post_thumbnail_id( $post );
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if ( ! $post_thumbnail_id ) {
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return false;
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}
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$thumbnail_url = wp_get_attachment_image_url( $post_thumbnail_id, $size );
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/**
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* Filters the post thumbnail URL.
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*
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* @since 5.9.0
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*
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* @param string|false $thumbnail_url Post thumbnail URL or false if the post does not exist.
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* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
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* @param string|int[] $size Registered image size to retrieve the source for or a flat array
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* of height and width dimensions. Default 'post-thumbnail'.
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*/
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return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
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}
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/**
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* Displays the post thumbnail URL.
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*
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* @since 4.4.0
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*
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* @param string|int[] $size Optional. Image size to use. Accepts any valid image size,
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* or an array of width and height values in pixels (in that order).
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* Default 'post-thumbnail'.
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*/
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function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
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$url = get_the_post_thumbnail_url( null, $size );
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if ( $url ) {
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echo esc_url( $url );
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}
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}
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/**
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* Returns the post thumbnail caption.
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*
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* @since 4.6.0
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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* @return string Post thumbnail caption.
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*/
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function get_the_post_thumbnail_caption( $post = null ) {
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$post_thumbnail_id = get_post_thumbnail_id( $post );
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if ( ! $post_thumbnail_id ) {
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return '';
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}
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$caption = wp_get_attachment_caption( $post_thumbnail_id );
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if ( ! $caption ) {
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$caption = '';
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}
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return $caption;
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}
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/**
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* Displays the post thumbnail caption.
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*
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* @since 4.6.0
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*
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* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
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*/
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function the_post_thumbnail_caption( $post = null ) {
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/**
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* Filters the displayed post thumbnail caption.
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*
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* @since 4.6.0
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*
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* @param string $caption Caption for the given attachment.
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*/
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echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
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}
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