简单使用１：
// timer to assist with displaying wait dialog
CPeriodic* iWaitTimer;
// create the timer used for callbacks
iWaitTimer = CPeriodic::NewL( CActive::EPriorityHigh );
if ( iWaitTimer->IsActive() )
{
PRINT( _L( "Camera <> timer already active" ) )
iWaitTimer->Cancel();
}
PRINT( _L( "Camera <> start the exit timer" ) )
iWaitTimer->Start( 0, 0, TCallBack( CallExit, this ) );
简单使用２：
Can be used to pass an action to an active object request
?
Takes a
value:
TAny
*
and function pointer:
TInt
(*
aFunction
)(
TAny
*
aPtr
)
?
aFunction
must be a non-member function or a static member function
?
The
TAny
*
value is passed to
aFunction
every time the
CallBack
()
function of
TCallBack
object is called
If a member function needs to be called, this can be done like this:
?
Use a static function of
CObject
?
Pass a
CObject
*
aObject
to
TCallBack
?
In the static function, call
aObject
->
MemberFunction
()
static TInt Function( TAny* param ); //belong to CObject
CObject* object = CObject::NewL();
TCallBack cb( Function, object );
cb.CallBack(); // results in call to Function( object );