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<concept id="GUID-89B12BB4-877E-4157-9BD1-81AD02EE3543" xml:lang="en"><title>Constructing

the UI controller in the view architecture</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The call on the first phase constructor method of the UI controller

occurs in the <xref href="GUID-935C59EE-AD66-33FE-987B-BD97F5147CC1.dita"><apiname>CAknDocument</apiname></xref>-derived class of application.

For more information, see <xref href="GUID-07D2ED79-90B2-4ABC-A61F-108DAEE21955.dita">Implementing

framework requirements</xref>.</p>

<p>The methods you need to implement for your <xref href="GUID-26F8606A-0803-3693-A022-3BB620D64C0E.dita"><apiname>CAknViewAppUI</apiname></xref>-derived

UI controller are as follows:</p>

<ul>

<li><p>C++ default constructor, which cannot contain any code that

might leave. A common implementation is:</p>

<itemgroup>

<codeblock id="GUID-ED243BA0-4466-47F3-8F17-0A901EE29671" xml:space="preserve">CMyViewAppAppUi::CMyViewAppAppUi()

    {    

    }</codeblock>

<p>The class declaration for this constructor in the class header file

needs to be public to support the construction method required.</p>

</itemgroup>

</li>

<li><p>Symbian 2nd phase constructor with code that might leave.

A common implementation is:</p>

<itemgroup>

<codeblock id="GUID-6665D735-D20A-4159-98B3-199BF15E7602" xml:space="preserve">

void CMyViewAppAppUi::ConstructL()

    {

    BaseConstructL(EAknEnableSkin); // Use EAknEnableSkin to make the application support themes.

    CMyViewAppView* view1 = CMyViewAppView::NewL();

    AddViewL( view1 );        // transfer ownership to CAknViewAppAppUi

	  iViewId1 = view1->Id();   // view id to get view from CAknViewAppAppUi

    CMyViewAppView2* view2 = CMyViewAppView2::NewL();

    AddViewL( view2 );      // transfer ownership to CAknViewAppAppUi

	  iViewId2 = view2->Id(); // view id to get view from CAknViewAppAppUi

    SetDefaultViewL( *view1 );

    }</codeblock>

<p><parmname>ConstructL</parmname> completes the construction of the object.

It is a public constructor in the header file.</p>

<p><xref href="GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E.dita#GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E/GUID-BD88511C-84FC-3FF5-BE29-230BE30A75E3"><apiname>CAknViewAppUi::BaseConstructL()</apiname></xref> initializes the application

UI with necessary UI components , including status and control panes. <xref href="GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E.dita#GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E/GUID-BD88511C-84FC-3FF5-BE29-230BE30A75E3"><apiname>CAknViewAppUi::BaseConstructL()</apiname></xref> can

accept flags enumerated in <xref href="GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E.dita"><apiname>CEikAppUi</apiname></xref> and <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita"><apiname>CAknAppUi</apiname></xref>.

In particular, the <xref href="GUID-77329067-34D9-3698-B764-294535E660EB.dita#GUID-77329067-34D9-3698-B764-294535E660EB/GUID-B0D8013D-5D6F-3A55-9601-A49614B4AAC8"><apiname>CAknAppUi::EAknEnableSkin()</apiname></xref> flag enables <xref href="GUID-A1DBE03F-728E-4F31-BE74-5BDA3906C8DD.dita">themes</xref> in the application.</p>

<p><parmname>CMyViewAppView* view1 = CMyViewAppView::NewL()</parmname> is

a two phase constructor for the <xref href="GUID-11967EBB-7439-3775-B287-7560ECA0AF1F.dita"><apiname>CAknView</apiname></xref>-derived view controller.</p>

<p><xref href="GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E.dita#GUID-2DBA2DA9-3DA7-381C-842C-9F6FEEDF973E/GUID-584748A3-5710-312D-BF76-2BC0BB7349EE"><apiname>CAknViewAppUi::AddViewL()</apiname></xref> registers and adds the

view controller to the UI controller.</p>

<p><xref href="GUID-79D1E4D4-A4D7-30B8-B936-F000ACE57507.dita"><apiname>iViewId1 = view1-&gt;Id()</apiname></xref> calls the view controller

method that provides the UID of the view controller.</p>

<p><xref href="GUID-3AC2CDAC-0291-309F-A020-049BC9F2CF90.dita#GUID-3AC2CDAC-0291-309F-A020-049BC9F2CF90/GUID-FAF8E2A8-991E-3337-9D88-907448E824FF"><apiname>CCoeAppUi::SetDefaultViewL()</apiname></xref> registers a view as

the default view of the application. The meaning of the default view varies

depending on the UI. It is normally the view that is displayed when the application

is launched. It may also be the view that is displayed when the application

is brought to the foreground.</p>

</itemgroup>

</li>

</ul>

<p>You must implement other methods to support <xref href="GUID-E402616A-7ED8-45AC-B836-99C3A3760B33.dita">key

event handling</xref>, <xref href="GUID-4941C035-C359-4968-9BD5-31F44EE5F810.dita">command

handling</xref>, and other possible <xref href="GUID-EF7FF39E-929F-4767-B475-5D582D37BB32.dita">events</xref>,

as well as overriding default <xref href="GUID-5918ED8A-B26B-41A0-94A6-AB6D51BF80A1.dita">control

pane</xref> and status pane behavior.</p>

<note>

<p>Command, key event, and layout change support handling can take place

at least partially in the view controller.</p>

</note>

<section id="GUID-4AA4BB6F-9331-4196-91F5-A3FF479667B2"><title>Scalability</title>

<p>If you wish to support <xref href="GUID-B02C762B-C452-4184-ABEA-4753E6CD47D2.dita">scalability</xref> in

your application, then you need to implement <xref href="GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E.dita#GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E/GUID-7B8E4FA3-29F4-39DF-BBB3-71E7AB2433C4"><apiname>CEikAppUi::HandleResourceChangeL()</apiname></xref> in

the UI controller , and then a <parmname>HandleClientRectChangeL</parmname> method

in the view controller.</p>

<p> A common implementation is:</p>

<codeblock id="GUID-ADB8DC30-EFF6-4F66-B418-78FD90A1B568" xml:space="preserve">void CMyViewAppAppUi::HandleResourceChangeL( TInt aType )

    {    	    

    CAknAppUi::HandleResourceChangeL( aType );	

    if ( aType==KEikDynamicLayoutVariantSwitch )

        {		

		((CMyViewAppView*) View( iViewId1) )->HandleClientRectChange(  );

		((CMyViewAppView2*) View( iViewId2) )->HandleClientRectChange(  );	        

		}	

    }   </codeblock>

<p>, where</p>

<p><xref href="GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E.dita#GUID-1185F595-0488-3E93-8D60-6B3A1A3AC32E/GUID-7B8E4FA3-29F4-39DF-BBB3-71E7AB2433C4"><apiname>CEikAppUi::HandleResourceChangeL()</apiname></xref> is a <xref href="GUID-DD15F24B-0786-4531-A6C5-A5E70EBE2732.dita">layout

change event method</xref>.</p>

<p><parmname>HandleClientRectChangeL</parmname> is a method in the view

controller for passing the change onto to the control</p>

</section>