Enabling drag events in Symbian C++ on touch-enabled devices

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Article Metadata

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Tested with

Devices(s): Nokia 5800 XpressMusic

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Compatibility

Platform(s): S60 5th Edition

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Article

Keywords: CCoeControl::EnableDragEvents()

Created: tepaa (03 Oct 2008)

Last edited: hamishwillee (14 Jun 2012)

Overview

S60 5th Edition supports touch events. All AVKON UI controls handle touch UI events and you do not need to implement anything new.

If you want to listen for drag events in your custom CCoeControl UI control, use CCoeControl::EnableDragEvents().

MMP file

The following libraries are required:

LIBRARY cone.lib

Header file

private:
    void ConstructL(const TRect& aRect);
    void HandlePointerEventL(const TPointerEvent& aPointerEvent);
    void Move(const TPoint& aPoint);
 
private:
    TPoint iMovePoint;

Source file

Enable drag event listening in the container control ConstructL().

EnableDragEvents() needs to be called only once in the entire application.

void CMyControl::ConstructL(const TRect& /*aRect*/)
    {
    // Create window of this container control
    CreateWindowL();
 
    // Enable drag events listening
    EnableDragEvents();
 
    // ...

Drag events are received.

void CMyControl::HandlePointerEventL(const TPointerEvent& aPointerEvent)
    {
    if (aPointerEvent.iType == TPointerEvent::EButton1Down)
        {
        iMovePoint = aPointerEvent.iPosition;
        }
    else if (aPointerEvent.iType == TPointerEvent::EDrag)
       {
       // Drag events received, what to do with it?
 
       // We could move this control...
       Move(aPointerEvent.iPosition);
 
       // Store current point
       iMovePoint = aPointerEvent.iPosition;
 
       // Draw this control again because we move to position of it
       DrawNow();
       }
 
    // ...

Moving control to dragging point:

void CMyControl::Move(const TPoint& aPoint)
    {
    TPoint offset;
 
    // Calculate moving offset
    offset.iX =  aPoint.iX - iMovePoint.iX;
    offset.iY = aPoint.iY - iMovePoint.iY;
 
    TRect rect = Rect();
 
    // Move this control
    rect.Move(offset);
    }

Postconditions

Drag events are received and control is moved to the pointer location.

See also

S60 5th Edition: Solitaire Game Example

S60 Platform: Image Converter Example

Handling pointer events in Symbian C++

CS001145 - Pointer capturing in touch-enabled devices