
如何创建WordPress网站浮动固定栏(页眉)
wp_calculate_image_sizes ( $size, $image_src = null, $image_meta = null, $attachment_id = 0 )
wp_calculate_image_sizes: 这个函数根据图像标签的尺寸、页面上的可用空间和用户的设备来计算其尺寸属性。
为图片创建一个’sizes’属性值。
function wp_calculate_image_sizes( $size, $image_src = null, $image_meta = null, $attachment_id = 0 ) { $width = 0; if ( is_array( $size ) ) { $width = absint( $size[0] ); } elseif ( is_string( $size ) ) { if ( ! $image_meta && $attachment_id ) { $image_meta = wp_get_attachment_metadata( $attachment_id ); } if ( is_array( $image_meta ) ) { $size_array = _wp_get_image_size_from_meta( $size, $image_meta ); if ( $size_array ) { $width = absint( $size_array[0] ); } } } if ( ! $width ) { return false; } // Setup the default 'sizes' attribute. $sizes = sprintf( '(max-width: %1$dpx) 100vw, %1$dpx', $width ); /** * Filters the output of 'wp_calculate_image_sizes()'. * * @since 4.4.0 * * @param string $sizes A source size value for use in a 'sizes' attribute. * @param string|int[] $size Requested image size. Can be any registered image size name, or * an array of width and height values in pixels (in that order). * @param string|null $image_src The URL to the image file or null. * @param array|null $image_meta The image meta data as returned by wp_get_attachment_metadata() or null. * @param int $attachment_id Image attachment ID of the original image or 0. */ return apply_filters( 'wp_calculate_image_sizes', $sizes, $size, $image_src, $image_meta, $attachment_id ); }