the_post_thumbnail
the_post_thumbnail 在 WordPress 中主要用来打印文章中设定的缩略图，而 get_the_post_thumbnail 函数可以将你需要的 HTML 代码以字符串的形式返回。
the_post_thumbnail 函数的使用
the_post_thumbnail( $size , $attr)
函数参数
$size 是指你想要的缩略图类型 默认是 ‘post-thumbnail’ 也就是特色图像
$attr 图像img标签中的属性设置。
the_post_thumbnail 函数声明
/**
* Display Post Thumbnail.
*
* @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.
*/
function the_post_thumbnail( $size = 'post-thumbnail', $attr = '' ) {
echo get_the_post_thumbnail( null, $size, $attr );
}get_the_post_thumbnail 函数声明
* Retrieve Post Thumbnail.
*
* @since 2.9.0
*
* @param int $post_id Optional. Post ID.
* @param string $size Optional. Image size. Defaults to 'post-thumbnail'.
* @param string|array $attr Optional. Query string or array of attributes.
*/
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 );
$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
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 );
} else {
$html = '';
}
return apply_filters( 'post_thumbnail_html', $html, $post_id, $post_thumbnail_id, $size, $attr );
}