WordPress/wp-includes/post-thumbnail-template.php

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<?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
*/
/**
Docs: Link to the "Conditional Tags" article in the Theme Developer Handbook from the descriptions for a variety of core conditional tag functions. These notations largely serve to direct consumers (of both the source and the parsed code reference) to extended information on individual and related conditional tags throughout WordPress. The changeset also standardizes corresponding DocBlock summaries to use third-person singular verbs. Notations been added for the following functions: * comments_open() * email exists() * has_excerpt() * has_post_thumbnail() * has_tag() * in_category() * in_the_loop() * is_404() * is_active_sidebar() * is_active_widget() * is_admin() * is_admin_bar_showing() * is_archive() * is_attachment() * is_author() * is_blog_installed() * is_category() * is_comments_popup() * is_date() * is_day() * is_dynamic_sidebar() * is_feed() * is_front_page() * is_home() * is_local_attachment() * is_main_query * is_month() * is_multi_author * is_new_day() * is_page() * is_page_template() * is_paged() * is_plugin_active() * is_plugin_active_for_network() * is_plugin_inactive() * is_plugin_page() * is_post_type_archive() * is_preview() * is_rtl() * is_search() * is_single() * is_singular() * is_sticky() * is_tag() * is_tax() * is_taxonomy_hierarchical() * is_time() * is_trackback() * is_user_logged_in() * is_year() * pings_open() * post_type_exists() * taxonomy_exists() * term_exists() * username exists() * wp_attachment_is_image() * wp_script_is() Props janalwin. Fixes #43254. Built from https://develop.svn.wordpress.org/trunk@42710 git-svn-id: http://core.svn.wordpress.org/trunk@42538 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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* Determines whether a post has an image attached.
*
Docs: Link to the "Conditional Tags" article in the Theme Developer Handbook from the descriptions for a variety of core conditional tag functions. These notations largely serve to direct consumers (of both the source and the parsed code reference) to extended information on individual and related conditional tags throughout WordPress. The changeset also standardizes corresponding DocBlock summaries to use third-person singular verbs. Notations been added for the following functions: * comments_open() * email exists() * has_excerpt() * has_post_thumbnail() * has_tag() * in_category() * in_the_loop() * is_404() * is_active_sidebar() * is_active_widget() * is_admin() * is_admin_bar_showing() * is_archive() * is_attachment() * is_author() * is_blog_installed() * is_category() * is_comments_popup() * is_date() * is_day() * is_dynamic_sidebar() * is_feed() * is_front_page() * is_home() * is_local_attachment() * is_main_query * is_month() * is_multi_author * is_new_day() * is_page() * is_page_template() * is_paged() * is_plugin_active() * is_plugin_active_for_network() * is_plugin_inactive() * is_plugin_page() * is_post_type_archive() * is_preview() * is_rtl() * is_search() * is_single() * is_singular() * is_sticky() * is_tag() * is_tax() * is_taxonomy_hierarchical() * is_time() * is_trackback() * is_user_logged_in() * is_year() * pings_open() * post_type_exists() * taxonomy_exists() * term_exists() * username exists() * wp_attachment_is_image() * wp_script_is() Props janalwin. Fixes #43254. Built from https://develop.svn.wordpress.org/trunk@42710 git-svn-id: http://core.svn.wordpress.org/trunk@42538 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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* For more information on this and similar theme functions, check out
* the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
Docs: Link to the "Conditional Tags" article in the Theme Developer Handbook from the descriptions for a variety of core conditional tag functions. These notations largely serve to direct consumers (of both the source and the parsed code reference) to extended information on individual and related conditional tags throughout WordPress. The changeset also standardizes corresponding DocBlock summaries to use third-person singular verbs. Notations been added for the following functions: * comments_open() * email exists() * has_excerpt() * has_post_thumbnail() * has_tag() * in_category() * in_the_loop() * is_404() * is_active_sidebar() * is_active_widget() * is_admin() * is_admin_bar_showing() * is_archive() * is_attachment() * is_author() * is_blog_installed() * is_category() * is_comments_popup() * is_date() * is_day() * is_dynamic_sidebar() * is_feed() * is_front_page() * is_home() * is_local_attachment() * is_main_query * is_month() * is_multi_author * is_new_day() * is_page() * is_page_template() * is_paged() * is_plugin_active() * is_plugin_active_for_network() * is_plugin_inactive() * is_plugin_page() * is_post_type_archive() * is_preview() * is_rtl() * is_search() * is_single() * is_singular() * is_sticky() * is_tag() * is_tax() * is_taxonomy_hierarchical() * is_time() * is_trackback() * is_user_logged_in() * is_year() * pings_open() * post_type_exists() * taxonomy_exists() * term_exists() * username exists() * wp_attachment_is_image() * wp_script_is() Props janalwin. Fixes #43254. Built from https://develop.svn.wordpress.org/trunk@42710 git-svn-id: http://core.svn.wordpress.org/trunk@42538 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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* 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 $post Optional. Post ID or WP_Post object. Default is global `$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, $thumbnail_id );
}
/**
* Retrieve post thumbnail ID.
*
* @since 2.9.0
* @since 4.4.0 `$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 $post Optional. Post ID or WP_Post object. Default is global `$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 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 );
}
/**
* 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|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 );
}
/**
* Update cache for thumbnails in the current loop.
*
* @since 3.2.0
*
* @global WP_Query $wp_query WordPress Query object.
*
* @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 ) {
$id = get_post_thumbnail_id( $post->ID );
if ( $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|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();
}
Media: Refine the heuristics to exclude certain images and iframes from being lazy-loaded to improve performance. This changeset implements the refined lazy-loading behavior outlined in https://make.wordpress.org/core/2021/07/15/refining-wordpress-cores-lazy-loading-implementation/ in order to improve the Largest Contentful Paint metric, which can see a regression from images or iframes above the fold being lazy-loaded. Adjusting this so far has been possible for developers via filters and still is, however this enhancement brings a more accurate behavior out of the box for the majority of themes. Specifically, this changeset skips the very first "content image or iframe" on the page from being lazy-loaded. "Content image or iframe" denotes any image or iframe that is found within content of any post in the current main query loop as well as any featured image of such a post. This applies both to "singular" as well as "archive" content: On a "singular" page the first image/iframe of the post is not lazy-loaded, while on an "archive" page the first image/iframe of the _first_ post in the query is not lazy-loaded. This approach refines the lazy-loading behavior correctly for the majority of themes, which use a single-column layout for post content. For themes with multi-column layouts, a new `wp_omit_loading_attr_threshold` filter can be used to change how many of the first images/iframes are being skipped from lazy-loaded (default is `1`). For example, a theme using a three-column grid of latest posts for archives could use the filter to override the threshold to `3` on archive pages, so that the first three content images/iframes would not be lazy-loaded. Props adamsilverstein, azaozz, flixos90, hellofromtonya, jonoaldersonwp, mte90, rviscomi, tweetythierry, westonruter. Fixes #53675. See #50425. Built from https://develop.svn.wordpress.org/trunk@52065 git-svn-id: http://core.svn.wordpress.org/trunk@51657 1a063a9b-81f0-0310-95a4-ce76da25c4cd
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// Get the 'loading' attribute value to use as default, taking precedence over the default from
// `wp_get_attachment_image()`.
$loading = wp_get_loading_attr_default( 'the_post_thumbnail' );
// Add the default to the given attributes unless they already include a 'loading' directive.
if ( empty( $attr ) ) {
$attr = array( 'loading' => $loading );
} elseif ( is_array( $attr ) && ! array_key_exists( 'loading', $attr ) ) {
$attr['loading'] = $loading;
} elseif ( is_string( $attr ) && ! preg_match( '/(^|&)loading=', $attr ) ) {
$attr .= '&loading=' . $loading;
}
$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 );
}
/**
* 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|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 );
}
/**
* Display 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 $post Optional. Post ID or WP_Post object. Default is global `$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 ) );
}