How to Handle Pointer Events in a Custom Control

Comments

30 Sep
2009

Article Review by savaj (20090930)

Handling pointer events in custom controls is often require during developing custom GUI applications. This article demonstrates how pointer position will validated against the control rectangle and the pointer events will be routed to appropriate control. The article is well explained and useful to beginners.

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This piece of code works, but logically error. CCoeControl::HandlePointerEventL(aPointerEvent); will dispatch the pointer event to proper control automatically, so the if blocks just redo the logical already provided by CCoeControl. And thus give a bad impression to developer that they have to maintain the pointer dispatching stuff by themselves in a container.(Just like the key process)

You need to do the dispatch by yourself only when the control contained by the container can't be accessed by container's CCoeControl *ComponentControl(TInt aIndex) const; function. Most time that's an error

User:bibu2651 17:10, 26 Jan 2010

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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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Platform Security

Signing Required: Self-Signed

Capabilities: None

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Article

Keywords: HandlePointerEventL(),Custom Control.

Created: vasant21 (26 Oct 2008)

Last edited: hamishwillee (30 May 2013)

Overview

This snippet shows how to handle pointer events in a custom control and route them to a proper component control by validating the pointer area against the control rect.

This snippet can be self-signed.

Preconditions

Here we assume that we already have a working code for custom control, and we also assume that we have two components: iEdwin1 and iEdwin2 in a custom control.

MMP file

The following capabilities and libraries are required:

CAPABILITY  None
LIBRARY cone.lib

#include <COECNTRL.H> 
 
void CCustomContainer::HandlePointerEventL(const TPointerEvent& aPointerEvent)
    {
     // Validate pointer position.
    if( iEdwin1->Rect().Contains( aPointerEvent.iPosition ) )
       {
       // click on edwin1 pass the pointer event. //
       iEdwin1->HandlePointerEventL( aPointerEvent );
       }
    else if( iEdwin2->Rect().Contains( aPointerEvent.iPosition ) )
       {
       // click on edwin2 pass the pointer event. //
       iEdwin2->HandlePointerEventL( aPointerEvent );
       }
    else
       {
       // simply calling the base class implementation //
       CCoeControl::HandlePointerEventL(aPointerEvent);
       }
    }

Postconditions

Pointer position will validated against the control rectangle and the pointer events will be routed to appropriate control.