Symbian3/SDK/Source/GUID-078E6232-31FA-5582-84B8-F5E3E4B14A05.dita
changeset 7 51a74ef9ed63
parent 0 89d6a7a84779
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-078E6232-31FA-5582-84B8-F5E3E4B14A05.dita	Wed Mar 31 11:11:55 2010 +0100
@@ -0,0 +1,46 @@
+<?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-078E6232-31FA-5582-84B8-F5E3E4B14A05" xml:lang="en"><title>How
+to start a heartbeat timer</title><shortdesc>Provides code snippet to show you how to start a heartbeat timer.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>A heartbeat timer, <codeph>CHeartbeat</codeph>, invokes a function at regular
+intervals. You must define a class that implements the <codeph>MBeating</codeph> interface
+to define:</p>
+<ul>
+<li id="GUID-5B54CE88-DE53-5635-BBF4-639B693C5BEC"><p>a function <codeph>Beat()</codeph> that
+is called if the heartbeat timer is in synchronisation with the system clock</p> </li>
+<li id="GUID-E20AD2FD-B847-52B6-8D1E-F01B2A971ABA"><p>a function <codeph>Synchronize()</codeph> that
+is called if the heartbeat timer has got out of synchronisation with the system
+clock</p> </li>
+</ul>
+<p>First, we define a class <codeph>CHeartbeatRunner</codeph> class that derives
+from <codeph>MBeating</codeph>. </p>
+<codeblock id="GUID-6D0B8C93-7F24-5002-A8FF-5C9F4C41EE7B" xml:space="preserve">class CHeartbeatRunner: public MBeating
+    {
+public:
+    // Implement MBeating
+    void Beat();
+    void Synchronize();
+
+    // Start timer
+    void StartTimer();
+private:
+    CHeartbeat* iHeartbeat;
+};</codeblock>
+<p>Then, we can start the heartbeat timer. We pass the time interval for the
+beats (allowable intervals are defined in 1/12s of a second by <codeph>TTimerLockSpec</codeph>),
+and the object implementing <codeph>MBeating</codeph>.</p>
+<codeblock id="GUID-C0BD2194-9FED-5C2B-B900-A028210CF78C" xml:space="preserve">void CHeartbeatRunner::StartTimer()
+    {
+    iHeartbeat=CHeartbeat::NewL(0); // neutral priority
+    iHeartbeat-&gt;Start(ETwelveOClock,this); // 1 second intervals
+    }</codeblock>
+</conbody></concept>
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