1 <?php

     2 /**

     3  * WordPress Post Thumbnail Template Functions.

     4  *

     5  * Support for post thumbnails

     6  * Themes function.php must call add_theme_support( 'post-thumbnails' ) to use these.

     7  *

     8  * @package WordPress

     9  * @subpackage Template

    10  */

    11 

    12 /**

    13  * Check if post has an image attached.

    14  *

    15  * @since 2.9.0

    16  *

    17  * @param int $post_id Optional. Post ID.

    18  * @return bool Whether post has an image attached.

    19  */

    20 function has_post_thumbnail( $post_id = null ) {

    21 	return (bool) get_post_thumbnail_id( $post_id );

    22 }

    23 

    24 /**

    25  * Retrieve Post Thumbnail ID.

    26  *

    27  * @since 2.9.0

    28  *

    29  * @param int $post_id Optional. Post ID.

    30  * @return int

    31  */

    32 function get_post_thumbnail_id( $post_id = null ) {

    33 	$post_id = ( null === $post_id ) ? get_the_ID() : $post_id;

    34 	return get_post_meta( $post_id, '_thumbnail_id', true );

    35 }

    36 

    37 /**

    38  * Display Post Thumbnail.

    39  *

    40  * @since 2.9.0

    41  *

    42  * @param string|array $size Optional. Image size. Defaults to 'post-thumbnail', which theme sets using set_post_thumbnail_size( $width, $height, $crop_flag );.

    43  * @param string|array $attr Optional. Query string or array of attributes.

    44  */

    45 function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {

    46 	echo get_the_post_thumbnail( null, $size, $attr );

    47 }

    48 

    49 /**

    50  * Update cache for thumbnails in the current loop

    51  *

    52  * @since 3.2

    53  *

    54  * @param object $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.

    55  */

    56 function update_post_thumbnail_cache( $wp_query = null ) {

    57 	if ( ! $wp_query )

    58 		$wp_query = $GLOBALS['wp_query'];

    59 

    60 	if ( $wp_query->thumbnails_cached )

    61 		return;

    62 

    63 	$thumb_ids = array();

    64 	foreach ( $wp_query->posts as $post ) {

    65 		if ( $id = get_post_thumbnail_id( $post->ID ) )

    66 			$thumb_ids[] = $id;

    67 	}

    68 

    69 	if ( ! empty ( $thumb_ids ) ) {

    70 		_prime_post_caches( $thumb_ids, false, true );

    71 	}

    72 

    73 	$wp_query->thumbnails_cached = true;

    74 }

    75 

    76 /**

    77  * Retrieve Post Thumbnail.

    78  *

    79  * @since 2.9.0

    80  *

    81  * @param int $post_id Optional. Post ID.

    82  * @param string $size Optional. Image size. Defaults to 'post-thumbnail'.

    83  * @param string|array $attr Optional. Query string or array of attributes.

    84  */

    85 function get_the_post_thumbnail( $post_id = null, $size = 'post-thumbnail', $attr = '' ) {

    86 	$post_id = ( null === $post_id ) ? get_the_ID() : $post_id;

    87 	$post_thumbnail_id = get_post_thumbnail_id( $post_id );

    88 

    89 	/**

    90 	 * Filter the post thumbnail size.

    91 	 *

    92 	 * @since 2.9.0

    93 	 *

    94 	 * @param string $size The post thumbnail size.

    95 	 */

    96 	$size = apply_filters( 'post_thumbnail_size', $size );

    97 

    98 	if ( $post_thumbnail_id ) {

    99 

   100 		/**

   101 		 * Fires before fetching the post thumbnail HTML.

   102 		 *

   103 		 * Provides "just in time" filtering of all filters in wp_get_attachment_image().

   104 		 *

   105 		 * @since 2.9.0

   106 		 *

   107 		 * @param string $post_id           The post ID.

   108 		 * @param string $post_thumbnail_id The post thumbnail ID.

   109 		 * @param string $size              The post thumbnail size.

   110 		 */

   111 		do_action( 'begin_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size );

   112 		if ( in_the_loop() )

   113 			update_post_thumbnail_cache();

   114 		$html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );

   115 

   116 		/**

   117 		 * Fires after fetching the post thumbnail HTML.

   118 		 *

   119 		 * @since 2.9.0

   120 		 *

   121 		 * @param string $post_id           The post ID.

   122 		 * @param string $post_thumbnail_id The post thumbnail ID.

   123 		 * @param string $size              The post thumbnail size.

   124 		 */

   125 		do_action( 'end_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size );

   126 

   127 	} else {

   128 		$html = '';

   129 	}

   130 	/**

   131 	 * Filter the post thumbnail HTML.

   132 	 *

   133 	 * @since 2.9.0

   134 	 *

   135 	 * @param string $html              The post thumbnail HTML.

   136 	 * @param string $post_id           The post ID.

   137 	 * @param string $post_thumbnail_id The post thumbnail ID.

   138 	 * @param string $size              The post thumbnail size.

   139 	 * @param string $attr              Query string of attributes.

   140 	 */

   141 	return apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );

   142 }