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

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

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

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

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

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

</ul><ul>

<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.

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

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

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

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

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

</ul><ul>

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

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

</ul><ul>

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

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

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

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

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

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

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

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

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

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

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

    {

    public:

        //construction

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

        void ConstructL();

        ~CNewView();

    private:

        // From MCoeView class

        void ViewActivatedL( const TVwsViewId& aPrevViewId, 

                             TUid aCustomMessageId, 

                             const TDesC8& aCustomMessage );    

        void ViewDeactivated();

        TVwsViewIdAndMessage ViewScreenDeviceChangedL();

        void ViewConstructL();

    private:

        CCoeAppUi& iCCoeAppUi;

        TVwsViewId& iViewId;

    };

</codeblock></context>