wp_calculate_image_srcset()

wp_calculate_image_srcset() — A helper function to calculate the image sources to include in a ‘srcset’ attribute.

Inputs: $size_array (int[]): An array of width and height values. Field $0 (int): The width in pixels. Field $1 (int): The height in pixels. $image_src (string): The ‘src’ of the image. $image_meta (array): The image meta data as returned by ‘wp_get_attachment_metadata()’. $attachment_id (int): Optional. The image attachment ID. Default 0.

Returns string|false: The ‘srcset’ attribute value. False on error or when only one source exists.