Function libheif_sys::heif_context_add_generic_metadata

pub unsafe extern "C" fn heif_context_add_generic_metadata(
    ctx: *mut heif_context,
    image_handle: *const heif_image_handle,
    data: *const c_void,
    size: c_int,
    item_type: *const c_char,
    content_type: *const c_char
) -> heif_error

Add generic, proprietary metadata to an image. You have to specify an ‘item_type’ that will identify your metadata. ‘content_type’ can be an additional type, or it can be NULL. For example, this function can be used to add IPTC metadata (IIM stream, not XMP) to an image. Although not standard, we propose to store IPTC data with item type=“iptc”, content_type=NULL.