<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
<!-- This component and the accompanying materials are made available under the terms of the License 
"Eclipse Public License v1.0" which accompanies this distribution, 
and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
<!-- Initial Contributors:
    Nokia Corporation - initial contribution.
Contributors: 
-->
<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-E402616A-7ED8-45AC-B836-99C3A3760B33" xml:lang="en"><title>Key events</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<fig id="GUID-9A1FDF4B-5FD8-4113-8D8E-E879B4C7C255"><title>Key presses generate key events</title><image href="GUID-C9429505-EEE7-4E64-BE0A-BC5D57D5B42C_d0e64219_href.png"/></fig>
<p>Key events are generated when a mobile device user presses one or more
mobile device key buttons. The application framework delivers the event to
the application that has focus. The <parmname>TKeyEvent</parmname> structure
is used to contain the key event details delivered to the application. For
more information on <parmname>TKeyEvent</parmname>, see <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Window_Server/TKeyEventStruct.html" format="application/java-archive"><parmname>TKeyEvent</parmname></xref>. </p>
<p>The structure is as follows:</p>
<codeblock id="GUID-467AB9BB-948F-49B6-A243-206314E90242" xml:space="preserve">struct TKeyEvent
    {
    TUint iCode;
    TInt iScanCode;
    TUint iModifiers; // State of modifier keys
    TInt iRepeats; // Count of auto repeats generated
    };
</codeblock>
<p>The following events are generated by means of a single key press and
release:</p>
<codeblock id="GUID-5FE1F179-8F7A-4653-9604-3CFC4B66AE33" xml:space="preserve">EEventKeyDown
EEventKey
EEventKeyUp

</codeblock>
<p>The first event indicates that a key has been pressed down. The second
event indicates that a character has been received from the keyboard. The
third event is sent when the button has been released. These events are described
in the <parmname>iCode</parmname> and <parmname>iSCanCode</parmname> members
of <parmname>TKeyEvent</parmname>.</p>
<p>For more information on possible data contained in <parmname>EEventKey</parmname>,
see <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/reference/reference-cpp/Kernel_Architecture_2/e32keys.hGlobals.html#%3a%3aTKeyCode" format="application/java-archive"><parmname>TKeyCode</parmname></xref>.</p>
<p>Key presses may be interpreted by a Front End Processor (FEP) and tied
to specific key events. For example, if a mobile device user presses the <parmname>2</parmname> key
twice, an active FEP could generate a key event code of <parmname>b</parmname>.</p>
<p> For more information on FEPs, see <xref href="jar:GUID-35228542-8C95-4849-A73F-2B4F082F0C44.jar!/sdk/doc_source/guide/Application-Framework-subsystem-guide/fepbase/FrontEndProcessorOverview.guide.html#ApplicationFrameworkOverview%2eFrontEndProcessorOverview%2emain" format="application/java-archive">Front End Processor overview</xref>.</p>
</conbody></concept>