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ActiveTcl User Guide
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NAME
Snack_AddCallback, Snack_RemoveCallback, Snack_ExecCallbacks -
track changes to Snack sound objects
SYNOPSIS
#include <snack.h>
Snack_AddCallback(sound, procedure, clientData)
Snack_RemoveCallback(sound, id)
Snack_ExecCallbacks(sound, flag)
ARGUMENTS
Sound *sound (in)
Sound object to attach the callback to.
updateProc *procedure (in)
Procedure to invoke when the sound data changes.
ClientData *clientData (in)
Arbitrary one-word value to pass to
procedure.
int id (in)
Unique identifer for the callback.
int flag (in)
Flag which specifies how the sound changed.
DESCRIPTION
Snack_AddCallback adds a callback procedure to
sound, that will be called whenever its content changes. It
returns an id number that can be used by
Snack_RemoveCallback to remove the callback. The
clientData parameter to procedure is a copy of the
clientData argument given to Snack_AddCallback when
the callback was created. Typically, clientData points to a
data structure containing application-specific
information about what to do in procedure.
Snack_ExecCallbacks is used in sub-commands so that changes
to a sound can be tracked for example Snack´s canvas item
types. The flag specifies whether all sound data has changed
(SNACK_NEW_SOUND) or if new data has been appended
(SNACK_MORE_DATA).