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<concept id="GUID-0C19D3F1-CF60-4760-8A77-242E14647738" xml:lang="en"><title>Touch

UI observer interfaces</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>To support the touch functionality in the UI components, following observer

interfaces are provided:</p>

<ul>

<li><p><b>Navigation decorator observer</b> (<codeph>MAknNaviDecoratorObserver</codeph>)-

It is used in the navigation pane. The interface receives an event indicating

that the decorator’s right or left arrow has been tapped (or the navi label).

Based on the event received, the observer implementation performs an action

(for example, raise the volume or change focus to the next tab). This observer

is useful when custom controls needs to be implemented  in the navigation

control. The observer can be set using <codeph>CAknNavigationDecorator::SetNaviDecoratorObserver()</codeph>.</p> <p/> </li>

<li><p><b>Long tap detector</b> (<codeph>CAknLongTapDetector</codeph>) - It

is an AVKON component that an application or control can use to receive long

tap events.</p><p>The long tap handler must inherit from <codeph>MAknLongTapDetectorCallBack</codeph> and

implement the <codeph>HandleLongTapEventL()</codeph> call back function for

long tap events.</p> <p>When the stylus/finger is held down in the same position,

an animation starts in about 0.15 s to show that the long tap functionality

has started. Animation is provided by AVKON and cannot be changed by the application

or control. However, animation can be turned off using the class <codeph>CAknLongTapDetector</codeph> in

the Touch UI utilities API.</p> <p>For implementation information, see the <xref href="GUID-92018B6B-3CBB-434D-9E61-F271C67E98E3.dita">Touch UI utilities API specification</xref>.</p></li>

<li><p><b>Double-click support in lists</b> - To receive double-click events

from a list or grid, the object that needs to be informed must implement and

register the <codeph>MEikListBoxObserver</codeph> interface via <codeph>CEikListBox::SetListBoxObserver()</codeph>. </p>After

registering, handle the <codeph>EEventItemDoubleClicked</codeph> event in<codeph>HandleListBoxEventL()</codeph> method. <p>If

single click is enabled, <codeph>EEventItemSingleClicked</codeph> event should

be handled instead.</p></li>

<li><p><b>Title pane touch observer</b> - The title pane touch observer enables

you to provide functionality for title pane touch events. For implementation

information, see the <xref format="html" href="specs/guides/Title_Pane_Touch_Observer_API_Specification/Title_Pane_Touch_Observer_API_Specification.html" scope="peer">Title pane touch observer API specification</xref>.</p></li>

</ul>