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

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

     3 <!-- This component and the accompanying materials are made available under the terms of the License 

     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: 

     9 -->

    10 <!DOCTYPE task

    11   PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

    12 <task id="GUID-A399508A-DE6A-490D-9BFB-4FCF56FF9D4C" xml:lang="en"><title>Derive

    13 a class from the MCoeView class</title><prolog><metadata><keywords/></metadata></prolog><taskbody>

    14 <context>       <p>Derive a class from the <codeph>MCoeView</codeph> class

    15 and provide the definition for each of the following functions:</p><ul>

    16 <li><p><codeblock xml:space="preserve">TVwsViewId ViewId() const</codeblock></p><p>This function

    17 defines the unique identifier of the view within the given application.</p></li>

    18 </ul><ul>

    19 <li><p><codeblock xml:space="preserve">void ViewActivatedL(const TVwsViewId&amp; aPrevViewId,TUid aCustomMessageId,const TDesC8&amp; aCustomMessage)</codeblock></p><p>This is the function is called by the operating system when a view is activated.

    20 The call gets several arguments: the view ID of the previous view that was

    21 displayed (in case a switch back to it is desired), and the identifier and

    22 text of a message that comes from the process that is activating the view.

    23 This message can convey specialized information, such as information on what

    24 to display, from the activating process.</p></li>

    25 </ul><ul>

    26 <li><p><codeblock xml:space="preserve">void ViewDeactivated()</codeblock></p><p>This function is

    27 called by the operating system when a view is deactivated. </p></li>

    28 </ul><ul>

    29 <li><p><codeblock xml:space="preserve">TVwsViewIdAndMessage ViewScreenDeviceChangedL()</codeblock></p><p>This

    30 function has a default implementation. It handles a change to the screen device

    31 returning the value of the <codeph>TVwsViewIdAndMessage</codeph> object. By

    32 default, returns the ID of the active view.</p><p>Cone provides a default

    33 screen device change handler <codeph>CCoeScreenDeviceChangeDefaultHandler</codeph>. <codeph>CCoeScreenDeviceChangeDefaultHandler</codeph> handles

    34 any screen device changes that occur while a view is active. It is used to

    35 activate a default view when a screen flip (changing the screen orientation,

    36 for example, landscape to portrait) occurs, if the currently active view does

    37 not implement <codeph>MCoeView::ViewScreenDeviceChangedL()</codeph>.</p></li>

    38 </ul><p>The following code snippet shows deriving a class from <codeph>MCoeView</codeph> and

    39 implementing the required functions:</p><codeblock xml:space="preserve">class CNewView : public MCoeView

    40     {

    41     public:

    42         //construction

    43         CNewView( const TVwsViewId& aViewId, CCoeAppUi& aAppUi );

    44         void ConstructL();

    45         ~CNewView();

    46     private:

    47         // From MCoeView class

    48         void ViewActivatedL( const TVwsViewId& aPrevViewId, 

    49                              TUid aCustomMessageId, 

    50                              const TDesC8& aCustomMessage );    

    51         void ViewDeactivated();

    52         TVwsViewIdAndMessage ViewScreenDeviceChangedL();

    53         void ViewConstructL();

    54     private:

    55         CCoeAppUi& iCCoeAppUi;

    56         TVwsViewId& iViewId;

    57     };

    58 </codeblock></context>

    59 </taskbody></task>