如果添加了具有3种尺寸的自定义：

add_image_size( \'small\', 111, 222, true );
add_image_size( \'medium\', 333, 333, true );
add_image_size( \'large\', 444, 555, true );

You would then use them in the theme files using the names you gave for the function like this:

<?php the_post_thumbnail(\'small\'); ?>

<?php the_post_thumbnail(\'medium\'); ?>

and:

<?php the_post_thumbnail(\'large\'); ?>

正在搜索Featured Image 我被引导到\\wp-admin\\edit-form-advanced.php, 在那里，我发现一个添加了回调参数post_thumbnail_meta_box.

然后我搜索了post_thumbnail_meta_box, 最终在\\wp-admin\\includes\\meta-boxes.php, 我们可以看到，WP通过以下方式获取帖子缩略图：

$thumbnail_id = get_post_meta( $post->ID, \'_thumbnail_id\', true );

echo _wp_post_thumbnail_html( $thumbnail_id );

return apply_filters( \'admin_post_thumbnail_html\', $content );

function admin_post_thumbnail_kittenifier( $content ) {
    // In reality, you might want to replicate some of the code from _wp_post_thumbnail_html(), but this gives you the idea
    return "<img src=\'http://placekitten.com/200/300\' alt=\'I can has toxoplasma gondii?\'/>";
}
add_filter( \'admin_post_thumbnail_html\', \'admin_post_thumbnail_kittenifier\' );