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    10 <!DOCTYPE concept

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

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

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

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

    15 interfaces are provided:</p>

    16 <ul>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    32 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>

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

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

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

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

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

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

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

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

    41 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>

    42 </ul>

    43 </conbody></concept>