WordPress 可用的缩略图函数

<?php

if( !defined( 'THEME_THUMBNAIL_PATH' ) ) define( 'THEME_THUMBNAIL_PATH', '/cache/theme-thumbnail' ); //存储目录

function biji_build_empty_index( $path ){ //生成空白首页

    $index = $path . '/index.php';

    if( is_file( $index ) ) return;

    wp_mkdir_p( $path );

    file_put_contents( $index, "<?php\n// Silence is golden.\n" );

}

function biji_crop_thumbnail( $url, $width, $height = null ){ //裁剪图片

    $width = (int) $width;

    $height = empty( $height ) ? $width : (int) $height;

    $hash = md5( $url );

    $file_path = constant( 'WP_CONTENT_DIR' ) . constant( 'THEME_THUMBNAIL_PATH' ) . "/$hash-$width-$height.jpg";

    $file_url = content_url( constant( 'THEME_THUMBNAIL_PATH' ) . "/$hash-$width-$height.jpg" );

    if( is_file( $file_path ) ) return $file_url;

    $editor = wp_get_image_editor( $url );

    if( is_wp_error( $editor ) ) return $url;

    $size = $editor->get_size();

    $dims = image_resize_dimensions( $size['width'], $size['height'], $width, $height, true );

    //if( !$dims ) return $url;

    $cmp = min( $size['width'] / $width, $size['height'] / $height );

    if( is_wp_error( $editor->crop( $dims[2], $dims[3], $width * $cmp, $height * $cmp, $width, $height ) ) ) return $url;

    biji_build_empty_index( constant( 'WP_CONTENT_DIR' ) . constant( 'THEME_THUMBNAIL_PATH' ) );

    return is_wp_error( $editor->save( $file_path, 'image/jpg' ) ) ? $url : $file_url;

}

//缩略图获取post_thumbnail

function post_thumbnail($width = 275,$height = 170 )

{

    global $post;

    //如果有特色图片则取特色图片

    if( has_post_thumbnail( $post->ID ) ){

        $thumbnail_ID = get_post_thumbnail_id( $post->ID );

        $thumbnailsrc = wp_get_attachment_image_src( $thumbnail_ID, 'full' );

        return biji_crop_thumbnail($thumbnailsrc[0],$width,$height);

    } else {

        $content = $post->post_content;

        preg_match_all('/<img.*?(?: |\\t|\\r|\\n)?src=[\'"]?(.+?)[\'"]?(?:(?: |\\t|\\r|\\n)+.*?)? >/sim', $content, $strResult, PREG_PATTERN_ORDER);

        if(count($strResult[1]) > 0) return biji_crop_thumbnail($strResult[1][0],$width,$height);

        else{

            return false;

        }

    }

}

?>

<?php if (post_thumbnail(110, 110)){ ?>

  <img src="<?php echo post_thumbnail(110, 110); ?>" srcset="<?php echo post_thumbnail(220, 220); ?> 2x"/>

<?php }else{

   echo '<i class="icon-file-text2"></i>';

  }?>