Reads the partial contents of a file.
A FileReadMoreCallback should be used to stop reading from the file when appropriate, else this function will behave exactly as load_contents_async. This operation can be finished by load_partial_contents_async.end.
Users of this function should be aware that
user_data is passed to both the
read_more_callback and the
cancellable is not null, then the operation can be cancelled by triggering the cancellable
object from another thread. If the operation was cancelled, the error g_io_error_cancelled will be returned.
optional Cancellable object, null to ignore
a FileReadMoreCallback to receive partial data and to specify whether further data should be read
a TaskReadyCallback to call when the request is satisfied
the data to pass to the callback functions