Function in WordPress D8 theme to capture the first image of an article and display it

取自 WordPress D8 主题;

路径 themed8modules ;

if ( ! function_exists( 'deel_thumbnail' ) ) :
function deel_thumbnail() {
    global $post;
    if ( has_post_thumbnail() ) {
        $domsxe = simplexml_load_string(get_the_post_thumbnail());
        $thumbnailsrc = $domsxe->attributes()->src;
        echo '';
    } else {
        $content = $post->post_content;
        preg_match_all('//sim', $content, $strResult, PREG_PATTERN_ORDER);
        $n = count($strResult[1]);
        if($n > 0){
            echo '';
        }else {
            echo '';
        }
    }
}
endif;