How to handle Layout change events

Layout change events are generated when the screen size or layout is changed. The S60 platform supports multiple screen resolutions[also called as "Scalable UI"]. Thus, layout awareness is particularly crucial for those applications to reorganize the position as required. Applications can detect the changes in layout with, for example, the following methods:

1. Controls can override the CCoeControl::HandleResourceChange() to detect the KEikDynamicLayoutVariantSwitch message.
The following example code for HandleResourceChange():

    void CMyControl::HandleResourceChange(TInt aType)
        {
        CCoeControl::HandleResourceChange(aType); //call base class implementation
        if ( aType==KEikDynamicLayoutVariantSwitch )
            {
            TRect rect;
            // ask where container's rectangle should be
            // EMainPane equals to area returned by
            //CEikAppUi::ClientRect()
            AknLayoutUtils::LayoutMetricsRect(AknLayoutUtils::EMainPane,rect);
            SetRect(rect);
            }
        } 

2. UI controllers can override the CEikAppUi::HandleResourceChangeL() to detect the KEikDynamicLayoutVariantSwitch message.

The following example code for HandleResourceChangeL():

    void CExampleAppUi::HandleResourceChangeL(TInt aType)
        {
        CAknAppUi::HandleResourceChangeL( aType );
        if ( aType == KEikDynamicLayoutVariantSwitch )
            {
            // do the re-layout of the components
            }
        // Controls derived from CCoeControl, handled in a
        // container class
        iExampleControlContainer->HandleResourceChange( aType );
        //Must not call this if the components are on the control stack
        //iView->HandleResourceChangeL( aType );
        }