3 * WordPress Post Thumbnail Template Functions.
5 * Support for post thumbnails
6 * Themes function.php must call add_theme_support( 'post-thumbnails' ) to use these.
13 * Check if post has an image attached.
17 * @param int $post_id Optional. Post ID.
18 * @return bool Whether post has an image attached.
20 function has_post_thumbnail( $post_id = NULL ) {
22 $post_id = ( NULL === $post_id ) ? $id : $post_id;
23 return !! get_post_thumbnail_id( $post_id );
27 * Retrieve Post Thumbnail ID.
31 * @param int $post_id Optional. Post ID.
34 function get_post_thumbnail_id( $post_id = NULL ) {
36 $post_id = ( NULL === $post_id ) ? $id : $post_id;
37 return get_post_meta( $post_id, '_thumbnail_id', true );
41 * Display Post Thumbnail.
45 * @param int $size Optional. Image size. Defaults to 'post-thumbnail', which theme sets using set_post_thumbnail_size( $width, $height, $crop_flag );.
46 * @param string|array $attr Optional. Query string or array of attributes.
48 function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
49 echo get_the_post_thumbnail( NULL, $size, $attr );
53 * Retrieve Post Thumbnail.
57 * @param int $post_id Optional. Post ID.
58 * @param string $size Optional. Image size. Defaults to 'thumbnail'.
59 * @param string|array $attr Optional. Query string or array of attributes.
61 function get_the_post_thumbnail( $post_id = NULL, $size = 'post-thumbnail', $attr = '' ) {
63 $post_id = ( NULL === $post_id ) ? $id : $post_id;
64 $post_thumbnail_id = get_post_thumbnail_id( $post_id );
65 $size = apply_filters( 'post_thumbnail_size', $size );
66 if ( $post_thumbnail_id ) {
67 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
68 $html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );
69 do_action( 'end_fetch_post_thumbnail_html', $post_id, $post_thumbnail_id, $size );
73 return apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );