insideout10 / wordlift-plugin

		$small  = get_the_post_thumbnail_url( $post_id, 'small' );

		$medium = get_the_post_thumbnail_url( $post_id, 'medium' );

		$large  = get_the_post_thumbnail_url( $post_id, 'large' );

		if ( $small && $width = self::get_image_width( $post_id, 'small' ) ) {

			$srcset[] = $small . ' ' . $width . 'w';

		}

		if ( $medium && $width = self::get_image_width( $post_id, 'medium' ) ) {

			$srcset[] = $medium . ' ' . $width . 'w';

		}

		if ( $small && $width = self::get_image_width( $post_id, 'small' ) ) {

			$srcset[] = $small . ' ' . $width . 'w';

		}

		if ( $medium && $width = self::get_image_width( $post_id, 'medium' ) ) {

			$srcset[] = $medium . ' ' . $width . 'w';

		}

		if ( $large && $width = self::get_image_width( $post_id, 'large' ) ) {

			$srcset[] = $large . ' ' . $width . 'w';

			$srcset[] = $medium . ' ' . $width . 'w';

		}

		if ( $large && $width = self::get_image_width( $post_id, 'large' ) ) {

			$srcset[] = $large . ' ' . $width . 'w';

		}

		$srcset_string = join( ",", $srcset );