<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/kernel/qtimer.cpp:42 --> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>TQTimer Class</title> <style type="text/css"><!-- fn { margin-left: 1cm; text-indent: -1cm; } a:link { color: #004faf; text-decoration: none } a:visited { color: #672967; text-decoration: none } body { background: #ffffff; color: black; } --></style> </head> <body> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr bgcolor="#E5E5E5"> <td valign=center> <a href="index.html"> <font color="#004faf">Home</font></a> | <a href="classes.html"> <font color="#004faf">All Classes</font></a> | <a href="mainclasses.html"> <font color="#004faf">Main Classes</font></a> | <a href="annotated.html"> <font color="#004faf">Annotated</font></a> | <a href="groups.html"> <font color="#004faf">Grouped Classes</font></a> | <a href="functions.html"> <font color="#004faf">Functions</font></a> </td> <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>TQTimer Class Reference</h1> <p>The TQTimer class provides timer signals and single-shot timers. <a href="#details">More...</a> <p><tt>#include <<a href="qtimer-h.html">ntqtimer.h</a>></tt> <p>Inherits <a href="ntqobject.html">TQObject</a>. <p><a href="qtimer-members.html">List of all member functions.</a> <h2>Public Members</h2> <ul> <li class=fn><a href="#TQTimer"><b>TQTimer</b></a> ( TQObject * parent = 0, const char * name = 0 )</li> <li class=fn><a href="#~TQTimer"><b>~TQTimer</b></a> ()</li> <li class=fn>bool <a href="#isActive"><b>isActive</b></a> () const</li> <li class=fn>int <a href="#start"><b>start</b></a> ( int msec, bool sshot = FALSE )</li> <li class=fn>void <a href="#changeInterval"><b>changeInterval</b></a> ( int msec )</li> <li class=fn>void <a href="#stop"><b>stop</b></a> ()</li> <li class=fn>int <a href="#timerId"><b>timerId</b></a> () const</li> </ul> <h2>Signals</h2> <ul> <li class=fn>void <a href="#timeout"><b>timeout</b></a> ()</li> </ul> <h2>Static Public Members</h2> <ul> <li class=fn>void <a href="#singleShot"><b>singleShot</b></a> ( int msec, TQObject * receiver, const char * member )</li> </ul> <hr><a name="details"></a><h2>Detailed Description</h2> The TQTimer class provides timer signals and single-shot timers. <p> <p> It uses <a href="qtimerevent.html">timer events</a> internally to provide a more versatile timer. TQTimer is very easy to use: create a TQTimer, call <a href="#start">start</a>() to start it and connect its <a href="#timeout">timeout</a>() to the appropriate slots. When the time is up it will emit the timeout() signal. <p> Note that a TQTimer object is destroyed automatically when its parent object is destroyed. <p> Example: <pre> TQTimer *timer = new TQTimer( myObject ); <a href="ntqobject.html#connect">connect</a>( timer, TQ_SIGNAL(<a href="#timeout">timeout</a>()), myObject, TQ_SLOT(timerDone()) ); timer-><a href="#start">start</a>( 2000, TRUE ); // 2 seconds single-shot timer </pre> <p> You can also use the static <a href="#singleShot">singleShot</a>() function to create a single shot timer. <p> As a special case, a TQTimer with timeout 0 times out as soon as all the events in the window system's event queue have been processed. <p> This can be used to do heavy work while providing a snappy user interface: <pre> TQTimer *t = new TQTimer( myObject ); <a href="ntqobject.html#connect">connect</a>( t, TQ_SIGNAL(<a href="#timeout">timeout</a>()), TQ_SLOT(processOneThing()) ); t-><a href="#start">start</a>( 0, FALSE ); </pre> <p> myObject->processOneThing() will be called repeatedly and should return quickly (typically after processing one data item) so that TQt can deliver events to widgets and stop the timer as soon as it has done all its work. This is the traditional way of implementing heavy work in GUI applications; multi-threading is now becoming available on more and more platforms, and we expect that null events will eventually be replaced by threading. <p> Note that TQTimer's accuracy depends on the underlying operating system and hardware. Most platforms support an accuracy of 20ms; some provide more. If TQt is unable to deliver the requested number of timer clicks, it will silently discard some. <p> An alternative to using TQTimer is to call <a href="ntqobject.html#startTimer">TQObject::startTimer</a>() for your object and reimplement the <a href="ntqobject.html#timerEvent">TQObject::timerEvent</a>() event handler in your class (which must, of course, inherit <a href="ntqobject.html">TQObject</a>). The disadvantage is that <a href="ntqobject.html#timerEvent">timerEvent</a>() does not support such high-level features as single-shot timers or signals. <p> Some operating systems limit the number of timers that may be used; TQt tries to work around these limitations. <p>See also <a href="events.html">Event Classes</a> and <a href="time.html">Time and Date</a>. <hr><h2>Member Function Documentation</h2> <h3 class=fn><a name="TQTimer"></a>TQTimer::TQTimer ( <a href="ntqobject.html">TQObject</a> * parent = 0, const char * name = 0 ) </h3> Constructs a timer called <em>name</em>, with the parent <em>parent</em>. <p> Note that the parent object's destructor will destroy this timer object. <h3 class=fn><a name="~TQTimer"></a>TQTimer::~TQTimer () </h3> Destroys the timer. <h3 class=fn>void <a name="changeInterval"></a>TQTimer::changeInterval ( int msec ) </h3> Changes the timeout interval to <em>msec</em> milliseconds. <p> If the timer signal is pending, it will be stopped and restarted; otherwise it will be started. <p> <p>See also <a href="#start">start</a>() and <a href="#isActive">isActive</a>(). <h3 class=fn>bool <a name="isActive"></a>TQTimer::isActive () const </h3> <p> Returns TRUE if the timer is running (pending); otherwise returns FALSE. <p>Example: <a href="tutorial1-11.html#x2376">t11/cannon.cpp</a>. <h3 class=fn>void <a name="singleShot"></a>TQTimer::singleShot ( int msec, <a href="ntqobject.html">TQObject</a> * receiver, const char * member )<tt> [static]</tt> </h3> This static function calls a slot after a given time interval. <p> It is very convenient to use this function because you do not need to bother with a <a href="ntqobject.html#timerEvent">timerEvent</a> or to create a local TQTimer object. <p> Example: <pre> #include <<a href="qapplication-h.html">ntqapplication.h</a>> #include <<a href="qtimer-h.html">ntqtimer.h</a>> int main( int argc, char **argv ) { <a href="ntqapplication.html">TQApplication</a> a( argc, argv ); TQTimer::<a href="#singleShot">singleShot</a>( 10*60*1000, &a, TQ_SLOT(<a href="ntqapplication.html#quit">quit</a>()) ); ... // create and show your widgets return a.<a href="ntqapplication.html#exec">exec</a>(); } </pre> <p> This sample program automatically terminates after 10 minutes (i.e. 600000 milliseconds). <p> The <em>receiver</em> is the receiving object and the <em>member</em> is the slot. The time interval is <em>msec</em>. <h3 class=fn>int <a name="start"></a>TQTimer::start ( int msec, bool sshot = FALSE ) </h3> Starts the timer with a <em>msec</em> milliseconds timeout, and returns the ID of the timer, or zero when starting the timer failed. <p> If <em>sshot</em> is TRUE, the timer will be activated only once; otherwise it will continue until it is stopped. <p> Any pending timer will be stopped. <p> <p>See also <a href="#singleShot">singleShot</a>(), <a href="#stop">stop</a>(), <a href="#changeInterval">changeInterval</a>(), and <a href="#isActive">isActive</a>(). <p>Examples: <a href="aclock-example.html#x1204">aclock/aclock.cpp</a>, <a href="dirview-example.html#x1704">dirview/dirview.cpp</a>, <a href="distributor-example.html#x2671">distributor/distributor.ui.h</a>, <a href="forever-example.html#x1053">forever/forever.cpp</a>, <a href="hello-example.html#x1639">hello/hello.cpp</a>, <a href="tutorial1-11.html#x2377">t11/cannon.cpp</a>, and <a href="tutorial1-13.html#x2407">t13/cannon.cpp</a>. <h3 class=fn>void <a name="stop"></a>TQTimer::stop () </h3> Stops the timer. <p> <p>See also <a href="#start">start</a>(). <p>Examples: <a href="dirview-example.html#x1705">dirview/dirview.cpp</a>, <a href="tutorial1-11.html#x2378">t11/cannon.cpp</a>, <a href="tutorial1-12.html#x2400">t12/cannon.cpp</a>, and <a href="tutorial1-13.html#x2408">t13/cannon.cpp</a>. <h3 class=fn>void <a name="timeout"></a>TQTimer::timeout ()<tt> [signal]</tt> </h3> <p> This signal is emitted when the timer is activated. <p>Examples: <a href="aclock-example.html#x1205">aclock/aclock.cpp</a>, <a href="dirview-example.html#x1706">dirview/dirview.cpp</a>, <a href="distributor-example.html#x2672">distributor/distributor.ui.h</a>, <a href="forever-example.html#x1054">forever/forever.cpp</a>, <a href="hello-example.html#x1640">hello/hello.cpp</a>, and <a href="tutorial1-11.html#x2379">t11/cannon.cpp</a>. <h3 class=fn>int <a name="timerId"></a>TQTimer::timerId () const </h3> <p> Returns the ID of the timer if the timer is running; otherwise returns -1. <!-- eof --> <hr><p> This file is part of the <a href="index.html">TQt toolkit</a>. 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