1<?php
  2/**
  3 * WordPress Post Thumbnail Template Functions.
  4 *
  5 * Support for post thumbnails.
  6 * Theme's functions.php must call add_theme_support( 'post-thumbnails' ) to use these.
  7 *
  8 * @package WordPress
  9 * @subpackage Template
 10 */
 11
 12/**
 13 * Determines whether a post has an image attached.
 14 *
 15 * For more information on this and similar theme functions, check out
 16 * the {@link https://developer.wordpress.org/themes/basics/conditional-tags/
 17 * Conditional Tags} article in the Theme Developer Handbook.
 18 *
 19 * @since 2.9.0
 20 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
 21 *
 22 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 23 * @return bool Whether the post has an image attached.
 24 */
 25function has_post_thumbnail( $post = null ) {
 26	$thumbnail_id  = get_post_thumbnail_id( $post );
 27	$has_thumbnail = (bool) $thumbnail_id;
 28
 29	/**
 30	 * Filters whether a post has a post thumbnail.
 31	 *
 32	 * @since 5.1.0
 33	 *
 34	 * @param bool             $has_thumbnail true if the post has a post thumbnail, otherwise false.
 35	 * @param int|WP_Post|null $post          Post ID or WP_Post object. Default is global `$post`.
 36	 * @param int|false        $thumbnail_id  Post thumbnail ID or false if the post does not exist.
 37	 */
 38	return (bool) apply_filters( 'has_post_thumbnail', $has_thumbnail, $post, $thumbnail_id );
 39}
 40
 41/**
 42 * Retrieves the post thumbnail ID.
 43 *
 44 * @since 2.9.0
 45 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
 46 * @since 5.5.0 The return value for a non-existing post
 47 *              was changed to false instead of an empty string.
 48 *
 49 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
 50 * @return int|false Post thumbnail ID (which can be 0 if the thumbnail is not set),
 51 *                   or false if the post does not exist.
 52 */
 53function get_post_thumbnail_id( $post = null ) {
 54	$post = get_post( $post );
 55
 56	if ( ! $post ) {
 57		return false;
 58	}
 59
 60	$thumbnail_id = (int) get_post_meta( $post->ID, '_thumbnail_id', true );
 61
 62	/**
 63	 * Filters the post thumbnail ID.
 64	 *
 65	 * @since 5.9.0
 66	 *
 67	 * @param int|false        $thumbnail_id Post thumbnail ID or false if the post does not exist.
 68	 * @param int|WP_Post|null $post         Post ID or WP_Post object. Default is global `$post`.
 69	 */
 70	return (int) apply_filters( 'post_thumbnail_id', $thumbnail_id, $post );
 71}
 72
 73/**
 74 * Displays the post thumbnail.
 75 *
 76 * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
 77 * is registered, which differs from the 'thumbnail' image size managed via the
 78 * Settings > Media screen.
 79 *
 80 * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
 81 * size is used by default, though a different size can be specified instead as needed.
 82 *
 83 * @since 2.9.0
 84 *
 85 * @see get_the_post_thumbnail()
 86 *
 87 * @param string|int[] $size Optional. Image size. Accepts any registered image size name, or an array of
 88 *                           width and height values in pixels (in that order). Default 'post-thumbnail'.
 89 * @param string|array $attr Optional. Query string or array of attributes. Default empty.
 90 */
 91function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
 92	echo get_the_post_thumbnail( null, $size, $attr );
 93}
 94
 95/**
 96 * Updates cache for thumbnails in the current loop.
 97 *
 98 * @since 3.2.0
 99 *
100 * @global WP_Query $wp_query WordPress Query object.
101 *
102 * @param WP_Query|null $wp_query Optional. A WP_Query instance. Defaults to the $wp_query global.
103 */
104function update_post_thumbnail_cache( $wp_query = null ) {
105	if ( ! $wp_query ) {
106		$wp_query = $GLOBALS['wp_query'];
107	}
108
109	if ( $wp_query->thumbnails_cached ) {
110		return;
111	}
112
113	$thumb_ids = array();
114
115	/*
116	 * $wp_query may contain an array of post objects or post IDs.
117	 *
118	 * This ensures the cache is primed for all post objects to avoid
119	 * `get_post()` calls in `get_the_post_thumbnail()` triggering an
120	 * additional database call for each post.
121	 */
122	$parent_post_ids = array();
123	foreach ( $wp_query->posts as $post ) {
124		if ( $post instanceof WP_Post ) {
125			$parent_post_ids[] = $post->ID;
126		} elseif ( is_int( $post ) ) {
127			$parent_post_ids[] = $post;
128		}
129	}
130	_prime_post_caches( $parent_post_ids, false, true );
131
132	foreach ( $wp_query->posts as $post ) {
133		$id = get_post_thumbnail_id( $post );
134		if ( $id ) {
135			$thumb_ids[] = $id;
136		}
137	}
138
139	if ( ! empty( $thumb_ids ) ) {
140		_prime_post_caches( $thumb_ids, false, true );
141	}
142
143	$wp_query->thumbnails_cached = true;
144}
145
146/**
147 * Retrieves the post thumbnail.
148 *
149 * When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
150 * is registered, which differs from the 'thumbnail' image size managed via the
151 * Settings > Media screen.
152 *
153 * When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
154 * size is used by default, though a different size can be specified instead as needed.
155 *
156 * @since 2.9.0
157 * @since 4.4.0 `$post` can be a post ID or WP_Post object.
158 *
159 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object.  Default is global `$post`.
160 * @param string|int[]     $size Optional. Image size. Accepts any registered image size name, or an array of
161 *                               width and height values in pixels (in that order). Default 'post-thumbnail'.
162 * @param string|array     $attr Optional. Query string or array of attributes. Default empty.
163 * @return string The post thumbnail image tag.
164 */
165function get_the_post_thumbnail( $post = null, $size = 'post-thumbnail', $attr = '' ) {
166	$post = get_post( $post );
167
168	if ( ! $post ) {
169		return '';
170	}
171
172	$post_thumbnail_id = get_post_thumbnail_id( $post );
173
174	/**
175	 * Filters the post thumbnail size.
176	 *
177	 * @since 2.9.0
178	 * @since 4.9.0 Added the `$post_id` parameter.
179	 *
180	 * @param string|int[] $size    Requested image size. Can be any registered image size name, or
181	 *                              an array of width and height values in pixels (in that order).
182	 * @param int          $post_id The post ID.
183	 */
184	$size = apply_filters( 'post_thumbnail_size', $size, $post->ID );
185
186	if ( $post_thumbnail_id ) {
187
188		/**
189		 * Fires before fetching the post thumbnail HTML.
190		 *
191		 * Provides "just in time" filtering of all filters in wp_get_attachment_image().
192		 *
193		 * @since 2.9.0
194		 *
195		 * @param int          $post_id           The post ID.
196		 * @param int          $post_thumbnail_id The post thumbnail ID.
197		 * @param string|int[] $size              Requested image size. Can be any registered image size name, or
198		 *                                        an array of width and height values in pixels (in that order).
199		 */
200		do_action( 'begin_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );
201
202		if ( in_the_loop() ) {
203			update_post_thumbnail_cache();
204		}
205
206		$html = wp_get_attachment_image( $post_thumbnail_id, $size, false, $attr );
207
208		/**
209		 * Fires after fetching the post thumbnail HTML.
210		 *
211		 * @since 2.9.0
212		 *
213		 * @param int          $post_id           The post ID.
214		 * @param int          $post_thumbnail_id The post thumbnail ID.
215		 * @param string|int[] $size              Requested image size. Can be any registered image size name, or
216		 *                                        an array of width and height values in pixels (in that order).
217		 */
218		do_action( 'end_fetch_post_thumbnail_html', $post->ID, $post_thumbnail_id, $size );
219
220	} else {
221		$html = '';
222	}
223
224	/**
225	 * Filters the post thumbnail HTML.
226	 *
227	 * @since 2.9.0
228	 *
229	 * @param string       $html              The post thumbnail HTML.
230	 * @param int          $post_id           The post ID.
231	 * @param int          $post_thumbnail_id The post thumbnail ID, or 0 if there isn't one.
232	 * @param string|int[] $size              Requested image size. Can be any registered image size name, or
233	 *                                        an array of width and height values in pixels (in that order).
234	 * @param string|array $attr              Query string or array of attributes.
235	 */
236	return apply_filters( 'post_thumbnail_html', $html, $post->ID, $post_thumbnail_id, $size, $attr );
237}
238
239/**
240 * Returns the post thumbnail URL.
241 *
242 * @since 4.4.0
243 *
244 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object.  Default is global `$post`.
245 * @param string|int[]     $size Optional. Registered image size to retrieve the source for or a flat array
246 *                               of height and width dimensions. Default 'post-thumbnail'.
247 * @return string|false Post thumbnail URL or false if no image is available. If `$size` does not match
248 *                      any registered image size, the original image URL will be returned.
249 */
250function get_the_post_thumbnail_url( $post = null, $size = 'post-thumbnail' ) {
251	$post_thumbnail_id = get_post_thumbnail_id( $post );
252
253	if ( ! $post_thumbnail_id ) {
254		return false;
255	}
256
257	$thumbnail_url = wp_get_attachment_image_url( $post_thumbnail_id, $size );
258
259	/**
260	 * Filters the post thumbnail URL.
261	 *
262	 * @since 5.9.0
263	 *
264	 * @param string|false     $thumbnail_url Post thumbnail URL or false if the post does not exist.
265	 * @param int|WP_Post|null $post          Post ID or WP_Post object. Default is global `$post`.
266	 * @param string|int[]     $size          Registered image size to retrieve the source for or a flat array
267	 *                                        of height and width dimensions. Default 'post-thumbnail'.
268	 */
269	return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
270}
271
272/**
273 * Displays the post thumbnail URL.
274 *
275 * @since 4.4.0
276 *
277 * @param string|int[] $size Optional. Image size to use. Accepts any valid image size,
278 *                           or an array of width and height values in pixels (in that order).
279 *                           Default 'post-thumbnail'.
280 */
281function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
282	$url = get_the_post_thumbnail_url( null, $size );
283
284	if ( $url ) {
285		echo esc_url( $url );
286	}
287}
288
289/**
290 * Returns the post thumbnail caption.
291 *
292 * @since 4.6.0
293 *
294 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
295 * @return string Post thumbnail caption.
296 */
297function get_the_post_thumbnail_caption( $post = null ) {
298	$post_thumbnail_id = get_post_thumbnail_id( $post );
299
300	if ( ! $post_thumbnail_id ) {
301		return '';
302	}
303
304	$caption = wp_get_attachment_caption( $post_thumbnail_id );
305
306	if ( ! $caption ) {
307		$caption = '';
308	}
309
310	return $caption;
311}
312
313/**
314 * Displays the post thumbnail caption.
315 *
316 * @since 4.6.0
317 *
318 * @param int|WP_Post|null $post Optional. Post ID or WP_Post object. Default is global `$post`.
319 */
320function the_post_thumbnail_caption( $post = null ) {
321	/**
322	 * Filters the displayed post thumbnail caption.
323	 *
324	 * @since 4.6.0
325	 *
326	 * @param string $caption Caption for the given attachment.
327	 */
328	echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
329}
330