1 <?xml version="1.0" encoding="utf-8"?>

     2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

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     4 "Eclipse Public License v1.0" which accompanies this distribution, 

     5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

     6 <!-- Initial Contributors:

     7     Nokia Corporation - initial contribution.

     8 Contributors: 

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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-DD15F24B-0786-4531-A6C5-A5E70EBE2732" xml:lang="en"><title>Layout

    13 change events</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>Layout change events are generated when the screen size or layout is

    15 changed. The Symbian platform supports multiple screen resolutions (<xref href="GUID-B02C762B-C452-4184-ABEA-4753E6CD47D2.dita">scalable UI</xref>). Thus,

    16 layout awareness is particularly crucial for those applications that implement

    17 a customized UI instead of using automatically scalable Avkon UI components.

    18 Applications can detect the changes in layout with, for example, the following

    19 methods:</p>

    20 <ul>

    21 <li><p>Controls can override the <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aHandleResourceChange%28TInt%29" format="application/java-archive"><parmname>CCoeControl::HandleResourceChange()</parmname></xref> to detect the <parmname>KEikDynamicLayoutVariantSwitch</parmname> message.</p>

    22 </li>

    23 <li><p>UI controllers can override the <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Control_Environment/CCoeControlClass.html#%3a%3aCCoeControl%3a%3aHandleResourceChange%28TInt%29" format="application/java-archive"><parmname>CCoeControl::HandleResourceChange()</parmname></xref> to detect the <parmname>KEikDynamicLayoutVariantSwitch</parmname> message. </p>

    24 </li>

    25 </ul>

    26 <p>The following example code demonstrates the implementation of <parmname>HandleResourceChange()</parmname>:</p>

    27 <codeblock id="GUID-8BF5353E-F09F-457A-826A-3F83ADEDF97E" xml:space="preserve">void CExampleControl::HandleResourceChange( TInt aType )

    28     {

    29     CCoeControl::HandleResourceChange(aType);

    30     //call base class implementation

    31     if( aType==KEikDynamicLayoutVariantSwitch )

    32         {

    33         TRect rect;

    34         // ask where container's rectangle should be

    35         // EMainPane equals to area returned by

    36         //CEikAppUi::ClientRect()

    37         AknLayoutUtils::LayoutMetricsRect( AknLayoutUtils::EMainPane,rect );

    38         SetRect( rect );

    39         }

    40     }

    41 </codeblock>

    42 <p>The following example code demonstrates the implementation of <parmname>HandleResourceChangeL()</parmname>:</p>

    43 <codeblock id="GUID-226A9867-C4C5-4286-B324-30EB17A4374D" xml:space="preserve">void CExampleAppUi::HandleResourceChangeL( TInt aType )

    44     {

    45     CAknAppUi::HandleResourceChangeL( aType );

    46     if( aType == KEikDynamicLayoutVariantSwitch )

    47         {

    48         // do the re-layout of the components

    49         }

    50     // Controls derived from CCoeControl, handled in a

    51     // container class

    52     iExampleControlContainer->HandleResourceChange( aType );

    53     //Must not call this if the components are on the control stack

    54     //iView->HandleResourceChangeL( aType );

    55     }

    56 </codeblock>

    57 <p>If <parmname>iExampleControlContainer</parmname> is added to the control

    58 stack, it will get its <parmname>HandleResourceChange()</parmname> called

    59 when a layout is switched and there is no need to call it explicitly. </p>

    60 <p>For a reference design of a layout-aware application using a custom

    61 UI, refer to the <i>S60 Platform: Scalable Screen-Drawing Example</i> available

    62 for download from <xref href="http://www.forum.nokia.com/info/sw.nokia.com/id/c5b4228b-992c-4636-8f48-753040760391/S60_Platform_Scalable_Screen_Drawing_Example_v1_3_en.zip.html" scope="external">Forum Nokia</xref>.</p>

    63 </conbody></concept>