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<td align="right" valign="top" width="230"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></td></tr></table><h1 align="center">Digital Clock Example</h1>

<p>Files:</p>

<ul>

<li><a href="widgets-digitalclock-digitalclock-cpp.html">widgets/digitalclock/digitalclock.cpp</a></li>

<li><a href="widgets-digitalclock-digitalclock-h.html">widgets/digitalclock/digitalclock.h</a></li>

<li><a href="widgets-digitalclock-main-cpp.html">widgets/digitalclock/main.cpp</a></li>

</ul>

<p>The Digital Clock example shows how to use <a href="qlcdnumber.html">QLCDNumber</a> to display a number with LCD-like digits.</p>

<center><img src="images/digitalclock-example.png" alt="Screenshot of the Digital Clock example" /></center><p>This example also demonstrates how <a href="qtimer.html">QTimer</a> can be used to update a widget at regular intervals.</p>

<h2>DigitalClock Class Definition</h2>

<p>The <tt>DigitalClock</tt> class provides a clock widget showing the time with hours and minutes separated by a blinking colon. We subclass <a href="qlcdnumber.html">QLCDNumber</a> and implement a private slot called <tt>showTime()</tt> to update the clock display:</p>

<pre>  class DigitalClock : public QLCDNumber

{

Q_OBJECT

public:

DigitalClock(QWidget *parent = 0);

private slots:

void showTime();

};</pre>

<h2>DigitalClock Class Implementation</h2>

<pre>  DigitalClock::DigitalClock(QWidget *parent)

: QLCDNumber(parent)

{

setSegmentStyle(Filled);

QTimer *timer = new QTimer(this);

connect(timer, SIGNAL(timeout()), this, SLOT(showTime()));

timer->start(1000);

showTime();

setWindowTitle(tr("Digital Clock"));

resize(150, 60);

}</pre>

<p>In the constructor, we first change the look of the LCD numbers. The <a href="qlcdnumber.html#SegmentStyle-enum">QLCDNumber::Filled</a> style produces raised segments filled with the foreground color (typically black). We also set up a one-second timer to keep track of the current time, and we connect its <a href="qtimer.html#timeout">timeout()</a> signal to the private <tt>showTime()</tt> slot so that the display is updated every second. Then, we call the <tt>showTime()</tt> slot; without this call, there would be a one-second delay at startup before the time is shown.</p>

<pre>  void DigitalClock::showTime()

{

QTime time = QTime::currentTime();

QString text = time.toString("hh:mm");

if ((time.second() % 2) == 0)

text[2] = ' ';

display(text);

}</pre>

<p>The <tt>showTime()</tt> slot is called whenever the clock display needs to be updated.</p>

<p>The current time is converted into a string with the format "hh:mm". When <a href="qtime.html#second">QTime::second</a>() is a even number, the colon in the string is replaced with a space. This makes the colon appear and vanish every other second.</p>

<p>Finally, we call <a href="qlcdnumber.html#intValue-prop">QLCDNumber::display</a>() to update the widget.</p>

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