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The gpgme_progress_cb_t
type is the type of functions usable as
progress callback function.
The arguments are specific to the crypto engine. More information about the progress information returned from the GnuPG engine can be found in the GnuPG source code in the file doc/DETAILS in the section PROGRESS.
The function gpgme_set_progress_cb
sets the function that is
used when progress information about a cryptographic operation is
available. The function progfunc needs to implemented by the
user, and whenever it is called, it is called with its first argument
being hook_value. By default, no progress callback function
is set.
Setting a callback function allows an interactive program to display progress information about a long operation to the user.
The user can disable the use of a progress callback function by
calling gpgme_set_progress_cb
with progfunc being
NULL
.
The function gpgme_get_progress_cb
returns the function that is
used to inform the user about the progress made in *progfunc,
and the first argument for this function in *hook_value. If no
progress callback is set, or ctx is not a valid pointer,
NULL
is returned in both variables.
progfunc or hook_value can be NULL
. In this case,
the corresponding value will not be returned.