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Enabling additional touch events for your application

The Symbian platform provides additional touch events to enable drag events and to specify screen areas for touch events.

By default, the Symbian platform sends only EButton1Up and EButton1Down touch events to applications.

If you want to enable EDrag touch events, implement CCoeControl::EnableDragEvents() in your container class.

When the mobile device user drags the stylus on the screen, TPointerEvent::EDrag() events are sent. When dragging stops, the application receives the event TPointerEvent::EButton1Up().

void CTableauControl::ConstructL( const TRect& aRect )
    {
    // This is parent window
    CreateWindowL();

    EnableDragEvents();

    SetRect( aRect );
    SetExtentToWholeScreen();
    
    
    // Initialize component array
    InitComponentArrayL();
    
    
	 //Implement your own logic here
  	 ActivateL();
    }

It is enough that the container control set EnableDragEvents() in its construction. EnableDragEvents() need not be set again for the child controls to receive dragging events.

Controlling which control receives a touch event

Particularly when you are receiving drag events it may be that an object in the window may be drawn by one control, while the pointer is over another control. In cases where you want to ensure that pointer events are received by the intended control, implement CCoeControl::SetPointerCapture().

When a control receives a TPointerEvent::EButton1Down() event, all events will be sent to this control until the next TPointerEvent::EButton1Up() event. If you want to have events to be sent to another control before theTPointerEvent::EButton1Up() event, call SetPointerCapture(ETrue) from the new control.

When the new control has received its pointer event and TPointerEvent::EButton1Up() has been received, you have to call SetPointerCapture(EFalse) from the new control to stop events being sent to it indefinitely.

Specifying screen areas for touch events

To specify screen areas (TRect) for touch events, see the example below.

void CTableauControl::HandlePointerEventL(const TPointerEvent& aPointerEvent)
    {
    // Does the user point exit text on screen? 
    // iExitRect is rectangle of the text area on screen.
    if (iExitRect.Contains(aPointerEvent.iPosition))
        {
        if (iEikonEnv->QueryWinL(_L("Klondike"),_L("Exit?")))
            {
            // Exit was pointed, then do exit   
            (static_cast<CKlondikeAppUi*>(iEikonEnv->AppUi()))->HandleCommandL(EEikCmdExit);
            return;
            }
        }
    ...
    }

Ignoring events other than pointer up in your control

In cases where you want to make sure your control receives only touch EButton1Up events after receiving a touch EButton1Down event, implement CCoeControl::IgnoreEventsUntilNextPointerUp().

Parent topic: Touch-specific events