/**
* WordPress Post Thumbnail Template Functions.
*
- * Support for post thumbnails
- * Themes function.php must call add_theme_support( 'post-thumbnails' ) to use these.
+ * 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 $post_id Optional. Post ID.
- * @return bool Whether post has an image attached.
+ * @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_id = null ) {
- return (bool) get_post_thumbnail_id( $post_id );
+function has_post_thumbnail( $post = null ) {
+ return (bool) get_post_thumbnail_id( $post );
}
/**
- * Retrieve Post Thumbnail ID.
+ * Retrieve post thumbnail ID.
*
* @since 2.9.0
+ * @since 4.4.0 `$post` can be a post ID or WP_Post object.
*
- * @param int $post_id Optional. Post ID.
- * @return int
+ * @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_id = null ) {
- $post_id = ( null === $post_id ) ? get_the_ID() : $post_id;
- return get_post_meta( $post_id, '_thumbnail_id', true );
+function get_post_thumbnail_id( $post = null ) {
+ $post = get_post( $post );
+ if ( ! $post ) {
+ return '';
+ }
+ return get_post_meta( $post->ID, '_thumbnail_id', true );
}
/**
- * Display Post Thumbnail.
+ * 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
*
- * @param int $size Optional. Image size. Defaults to 'post-thumbnail', which theme sets using set_post_thumbnail_size( $width, $height, $crop_flag );.
- * @param string|array $attr Optional. Query string or array of attributes.
+ * @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
+ * Update cache for thumbnails in the current loop.
+ *
+ * @since 3.2.0
+ *
+ * @global WP_Query $wp_query
*
- * @since 3.2
+ * @param WP_Query $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.
*/
-function update_post_thumbnail_cache() {
- global $wp_query;
+function update_post_thumbnail_cache( $wp_query = null ) {
+ if ( ! $wp_query )
+ $wp_query = $GLOBALS['wp_query'];
if ( $wp_query->thumbnails_cached )
return;
}
if ( ! empty ( $thumb_ids ) ) {
- get_posts( array(
- 'update_post_term_cache' => false,
- 'include' => $thumb_ids,
- 'post_type' => 'attachment',
- 'post_status' => 'inherit',
- 'nopaging' => true
- ) );
+ _prime_post_caches( $thumb_ids, false, true );
}
$wp_query->thumbnails_cached = true;
}
/**
- * Retrieve Post Thumbnail.
+ * Retrieve the post thumbnail.
+ *
+ * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
+ * is registered, which differs from the 'thumbnail' image size managed via the
+ * Settings > Media screen.
+ *
+ * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
+ * size is used by default, though a different size can be specified instead as needed.
*
* @since 2.9.0
+ * @since 4.4.0 `$post` can be a post ID or WP_Post object.
*
- * @param int $post_id Optional. Post ID.
- * @param string $size Optional. Image size. Defaults to 'thumbnail'.
- * @param string|array $attr Optional. Query string or array of attributes.
+ * @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_id = null, $size = 'post-thumbnail', $attr = '' ) {
- $post_id = ( null === $post_id ) ? get_the_ID() : $post_id;
- $post_thumbnail_id = get_post_thumbnail_id( $post_id );
+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
+ *
+ * @param string|array $size The post thumbnail size. Image size or array of width and height
+ * values (in that order). Default 'post-thumbnail'.
+ */
$size = apply_filters( 'post_thumbnail_size', $size );
+
if ( $post_thumbnail_id ) {
- do_action( 'begin_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size ); // for "Just In Time" filtering of all of wp_get_attachment_image()'s filters
+
+ /**
+ * 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 );
- do_action( 'end_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size );
+
+ /**
+ * 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 = '';
}
- return apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );
+ /**
+ * 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 ) );
+}
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