Closing a dialog after a timeout using Symbian C++
This code snippet shows how to create a dialog that will close after a specified amount of time. Obviously the actually closing of the dialog can be made dependent on other factors including for example when the inactivity timer times out.
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Header file
There are three header files, one for the timer interface, one for the timer and one for the dialog that implements the timer interface.
First the interface for the timer to callback on when the timer expires.
This will be implemented by observers who need to know when the timer condition has been met
class MTimerCallback
{
public:
virtual void HandleTimedOut() = 0;
};
Next the timer object it self which will call the MTimerCallback interface above when the timer expires
class CTimerCallback : public CTimer
{
public:
static CTimerCallback* NewL(MTimerCallback& aCallback);
private:
CTimerCallback(MTimerCallback& aCallback);
void ConstructL();
void RunL();
private:
MTimerCallback& iCallback;
};
Finally we have dialog that will be requesting information from the user
and will be closed automatically when the timer fires
class CSymbianExampleQueryDialog
: public CAknTextQueryDialog, public MTimerCallback
{
public:
static CSymbianExampleQueryDialog* NewL(TDes& aDataText);
~CSymbianExampleQueryDialog();
public: //MTimerCallback
void HandleTimedOut();
public: // CAknTextQueryDialog
void PostLayoutDynInitL();
private:
CSymbianExampleQueryDialog(TDes& aDataText);
private:
CTimerCallback* iCallBack;
};
Source file
The code for the timer looks like any other timer implementation.
This particular implementation starts the timer when the object is constructed since it results in less code all round for the example.
static CTimerCallback* CTimerCallback::NewL(MTimerCallback& aCallback)
{
CTimerCallback* self = new (ELeave) CTimerCallback(aCallback);
CleanupStack::PushL(self);
self->ConstructL();
CleanupStack::Pop(self);
return self;
}
CTimerCallback::CTimerCallback(MTimerCallback& aCallback)
: CTimer(CActive::EPriorityStandard),
iCallback(aCallback)
{
CActiveScheduler::Add(this);
}
void CTimerCallback::ConstructL()
{
CTimer::ConstructL();
// TODO: Your own conditions such as At or Inactivity for example
// This example hardcodes 5 seconds
const TTimeIntervalMicroSeconds32 KFiveSeconds(5 * 1000000);
After(KFiveSeconds);
}
void CTimerCallback::RunL()
{
// TODO: Handle error conditions such as clock skew adjustment
// and time changes
iCallback.HandleTimedOut();
}
The final "glue" to hold it all together is the implementation of the dialog To make this simple, the provided code just inherits from CAknTextQueryDialog
This is where the "magic" happens. When the dialog is constructed, the timer is also started (as above with a 5 second timeout). The implementation of the MTimerCallback inteface is also passed to the timer and so when the timer expires the HandleTimedOut method is called and this just calls TryExitL to exit the dialog asynchronously
CSymbianExampleQueryDialog* CSymbianExampleQueryDialog::NewL(TDes& aDataText)
{
CSymbianExampleQueryDialog* self = new (ELeave) CSymbianExampleQueryDialog(aDataText);
CleanupStack::PushL(self);
CleanupStack::Pop(self);
return self;
}
CSymbianExampleQueryDialog::~CSymbianExampleQueryDialog()
{
delete iCallBack;
iCallBack = NULL;
}
void CSymbianExampleQueryDialog::HandleTimedOut()
{
TRAPD(err, TryExitL(EAknSoftkeyCancel));
}
void CSymbianExampleQueryDialog::PostLayoutDynInitL()
{
iCallBack = CTimerCallback::NewL(*this);
}
CSymbianExampleQueryDialog::CSymbianExampleQueryDialog(TDes& aDataText)
: CAknTextQueryDialog(aDataText)
{
}
Postconditions
The dialog will be closed when the timer expires
09 Sep
2009
This is a very well explained article on how to close a dialog after a specified amount of time. This could be useful to show some messages or notifications you would like to have it closed after displaying it for a set amount of time; It could be modified to have it closed, after some tasks have been completed.