描述:
获取文章的缩略图,该函数会直接返回带有img标签的缩略图。
用法:
<?php echo get_the_post_thumbnail('', '', 'style=border:0;'); ?>
参数:
$post
(string)默认值:null
文章的ID,或者WP_Post对象
$size
(string)默认值:post-thumbnail
指定要返回的缩略图尺寸
$attr
(string)默认为空
为img标签添加一个属性
返回值:
此函数返回如下结构的img标签:
<img width="400" height="300" src="" class="attachment- size- wp-post-image" alt="" style="border: 0;" />
源文件:
/**
* Retrieve the post thumbnail.
*
* When a theme adds 'post-thumbnail' support, a special 'post-thumbnail' image size
* is registered, which differs from the 'thumbnail' image size managed via the
* Settings > Media screen.
*
* When using the_post_thumbnail() or related functions, the 'post-thumbnail' image
* size is used by default, though a different size can be specified instead as needed.
*
* @since 2.9.0
* @since 4.4.0 `$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|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 = 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|array $size The post thumbnail size. Image size or array of width and height
* values (in that order). Default 'post-thumbnail'.
* @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 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 );
/**
* 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 = '';
}
/**
* 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 );
}