Symbian Example

You can capture key presses globally, when your application is not on screen or even from the invisible exe silently running in the background.

This demo is an ExeDll program that creates an invisible window and makes the Window server pass all the Left key presses to the program. You can run it on the emulator with the help of ExeLauncher


void CGlobalCapturer::StartCapturingL()
{
// Connect to the window server
User::LeaveIfError( iWsSession.Connect() );
// Create an invisible window group. Well, we'll make it invisible later
iWindowGroup = new (ELeave) RWindowGroup ( iWsSession );
// @see RBlankWindow::Construct
iWindowGroup->Construct( (TUint32)iWindowGroup, EFalse );

// Capture a key
User::LeaveIfError( iCaptureHandle = iWindowGroup->CaptureKey(
KKeyCode , 0, 0 ) );
// Send created window to the background and hide it from the
// application switcher
iWindowGroup->SetOrdinalPosition(-1);
iWindowGroup->EnableReceiptOfFocus( EFalse );
iWindowGroupName = CApaWindowGroupName::NewL( iWsSession );
iWindowGroupName->SetHidden(ETrue);
iWindowGroupName->SetWindowGroupName( *iWindowGroup );

// Tell window server, that we are ready to receive events
iWsSession.EventReady( &this->iStatus );
CActiveScheduler::Add( this );
SetActive();
}

// Key press happened
void CGlobalCapturer::RunL()
{
if( iStatus == KErrNone )
{
// EEventKey received
console->Write( _L( "Captured key press\n" ) );
TWsEvent we;
iWsSession.GetEvent( we );

if( we.Key()->iCode == KKeyCode )
{
console->Printf( _L( "Captured correct key press for the %i \
time\n" ), ++iCaptureCounter );
}
else
{
// This should never happen, but just to demonstrate how
// it is possible to forward events to the default destination
TInt foregroundAppId = iWsSession.GetFocusWindowGroup();
iWsSession.SendEventToWindowGroup( foregroundAppId, we );
} // if iCode
if( iCaptureCounter == KNumberOfPressesToCapture )
{
// exit MainL() inner loop
CActiveScheduler::Stop();
}
else
{
iWsSession.EventReady( &iStatus );
SetActive();
} // if captured enough times
} // if iStatus
else
{
// Framework notified of some error
/** @todo Handle error if required */
}
}