<?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
*/
/**
* Determines whether a post has an image attached.
*
* For more information on this and similar theme functions, check out
* the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
* Conditional Tags} article in the Theme Developer Handbook.
*
* @since 2.9.0
* @since 4.4.0 `$post` can be a post ID or WP_Post object.
*
* @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @return bool Whether the post has an image attached.
*/
function has_post_thumbnail( $post = null ) {
$thumbnail_id = get_post_thumbnail_id( $post );
$has_thumbnail = (bool) $thumbnail_id;
/**
* Filters whether a post has a post thumbnail.
*
* @since 5.1.0
*
* @param bool $has_thumbnail true if the post has a post thumbnail, otherwise false.
* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
* @param int|false $thumbnail_id Post thumbnail ID or false if the post does not exist.
*/
return (bool) apply_filters( 'has_post_thumbnail', $has_thumbnail, $post, $thumbnail_id );
}
/**
* Retrieves the post thumbnail ID.
*
* @since 2.9.0
* @since 4.4.0 `$post` can be a post ID or WP_Post object.
* @since 5.5.0 The return value for a non-existing post
* was changed to false instead of an empty string.
*
* @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @return int|false Post thumbnail ID (which can be 0 if the thumbnail is not set),
* or false if the post does not exist.
*/
function get_post_thumbnail_id( $post = null ) {
$post = get_post( $post );
if ( ! $post ) {
return false;
}
$thumbnail_id = (int) get_post_meta( $post->ID, '_thumbnail_id', true );
/**
* Filters the post thumbnail ID.
*
* @since 5.9.0
*
* @param int|false $thumbnail_id Post thumbnail ID or false if the post does not exist.
* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
*/
return (int) apply_filters( 'post_thumbnail_id', $thumbnail_id, $post );
}
/**
* Displays 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|int[] $size Optional. Image size. Accepts any registered image size name, 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 );
}
/**
* Updates cache for thumbnails in the current loop.
*
* @since 3.2.0
*
* @global WP_Query $wp_query WordPress Query object.
*
* @param WP_Query|null $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();
/*
* $wp_query may contain an array of post objects or post IDs.
*
* This ensures the cache is primed for all post objects to avoid
* `get_post()` calls in `get_the_post_thumbnail()` triggering an
* additional database call for each post.
*/
$parent_post_ids = array();
foreach ( $wp_query->posts as $post ) {
if ( $post instanceof WP_Post ) {
$parent_post_ids[] = $post->ID;
} elseif ( is_int( $post ) ) {
$parent_post_ids[] = $post;
}
}
_prime_post_caches( $parent_post_ids, false, true );
foreach ( $wp_query->posts as $post ) {
$id = get_post_thumbnail_id( $post );
if ( $id ) {
$thumb_ids[] = $id;
}
}
if ( ! empty( $thumb_ids ) ) {
_prime_post_caches( $thumb_ids, false, true );
}
$wp_query->thumbnails_cached = true;
}
/**
* Retrieves the post thumbnail.
*
* When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
* is registered, which differs from the 'thumbnail' image size managed via the
* Settings > Media screen.
*
* When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
* size is used by default, though a different size can be specified instead as needed.
*
* @since 2.9.0
* @since 4.4.0 `$post` can be a post ID or WP_Post object.
*
* @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @param string|int[] $size Optional. Image size. Accepts any registered image size name, 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|int[] $size Requested image size. Can be any registered image size name, or
* an array of width and height values in pixels (in that order).
* @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 int $post_thumbnail_id The post thumbnail ID.
* @param string|int[] $size Requested image size. Can be any registered image size name, or
* an array of width and height values in pixels (in that order).
*/
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 int $post_thumbnail_id The post thumbnail ID.
* @param string|int[] $size Requested image size. Can be any registered image size name, or
* an array of width and height values in pixels (in that order).
*/
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 int $post_thumbnail_id The post thumbnail ID, or 0 if there isn't one.
* @param string|int[] $size Requested image size. Can be any registered image size name, or
* an array of width and height values in pixels (in that order).
* @param string|array $attr Query string or array of attributes.
*/
return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
}
/**
* Returns the post thumbnail URL.
*
* @since 4.4.0
*
* @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @param string|int[] $size Optional. Registered image size to retrieve the source for or a flat array
* of height and width dimensions. Default 'post-thumbnail'.
* @return string|false Post thumbnail URL or false if no image is available. If `$size` does not match
* any registered image size, the original image URL will be returned.
*/
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;
}
$thumbnail_url = wp_get_attachment_image_url( $post_thumbnail_id, $size );
/**
* Filters the post thumbnail URL.
*
* @since 5.9.0
*
* @param string|false $thumbnail_url Post thumbnail URL or false if the post does not exist.
* @param int|WP_Post|null $post Post ID or WP_Post object. Default is global `$post`.
* @param string|int[] $size Registered image size to retrieve the source for or a flat array
* of height and width dimensions. Default 'post-thumbnail'.
*/
return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
}
/**
* Displays the post thumbnail URL.
*
* @since 4.4.0
*
* @param string|int[] $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|null $post Optional. Post ID or WP_Post object. Default is global `$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|null $post Optional. Post ID or WP_Post object. Default is global `$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 ) );
}