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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>
Qt Toolkit - hello/main.cpp example file
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<h1 align=center>Hello, World</h1><br clear="all">
This example brings up the words "Hello, World" moving up and down,
and in different colors.
<hr>
Header file: <pre>/****************************************************************************
** $Id: qt/examples/hello/hello.h 2.3.2 edited 2001-01-26 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#ifndef HELLO_H
#define HELLO_H
#include <<a href="qwidget-h.html">qwidget.h</a>>
class Hello : public QWidget
{
Q_OBJECT
public:
Hello( const char *text, QWidget *parent=0, const char *name=0 );
signals:
void clicked();
protected:
void mouseReleaseEvent( <a href="qmouseevent.html">QMouseEvent</a> * );
void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );
private slots:
void animate();
private:
<a href="qstring.html">QString</a> t;
int b;
};
#endif
</pre>
<hr>
Implementation: <pre>/****************************************************************************
** $Id: qt/examples/hello/hello.cpp 2.3.2 edited 2001-01-26 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#include "hello.h"
#include <<a href="qpushbutton-h.html">qpushbutton.h</a>>
#include <<a href="qtimer-h.html">qtimer.h</a>>
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qpixmap-h.html">qpixmap.h</a>>
/*
Constructs a Hello widget. Starts a 40 ms animation timer.
*/
Hello::Hello( const char *text, QWidget *parent, const char *name )
: <a href="qwidget.html">QWidget</a>(parent,name), t(text), b(0)
{
<a href="qtimer.html">QTimer</a> *timer = new <a href="qtimer.html">QTimer</a>(this);
<a href="qobject.html#7f8e37">connect</a>( timer, SIGNAL(timeout()), SLOT(<a href=#371>animate</a>()) );
timer-><a href="qtimer.html#ce33bc">start</a>( 40 );
<a href="qwidget.html#8fcbbe">resize</a>( 260, 130 );
}
/*
This private slot is called each time the timer fires.
*/
void <a name="371"></a>Hello::animate()
{
b = (b + 1) & 15;
<a href="qwidget.html#7569b1">repaint</a>( FALSE );
}
/*
Handles mouse button release events for the Hello widget.
We emit the clicked() signal when the mouse is released inside
the widget.
*/
void <a name="372"></a>Hello::mouseReleaseEvent( <a href="qmouseevent.html">QMouseEvent</a> *e )
{
if ( rect().contains( e-><a href="qmouseevent.html#ac6f25">pos</a>() ) )
emit clicked();
}
/*
Handles paint events for the Hello widget.
Flicker-free update. The text is first drawn in the pixmap and the
pixmap is then blt'ed to the screen.
*/
void <a name="373"></a>Hello::paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * )
{
static int sin_tbl[16] = {
0, 38, 71, 92, 100, 92, 71, 38, 0, -38, -71, -92, -100, -92, -71, -38};
if ( t.isEmpty() )
return;
// 1: Compute some sizes, positions etc.
<a href="qfontmetrics.html">QFontMetrics</a> fm = fontMetrics();
int w = fm.<a href="qfontmetrics.html#3b6f39">width</a>(t) + 20;
int h = fm.<a href="qfontmetrics.html#341253">height</a>() * 2;
int pmx = width()/2 - w/2;
int pmy = height()/2 - h/2;
// 2: Create the pixmap and fill it with the widget's background
<a href="qpixmap.html">QPixmap</a> pm( w, h );
pm.<a href="qpixmap.html#6910a0">fill</a>( this, pmx, pmy );
// 3: Paint the pixmap. Cool wave effect
<a href="qpainter.html">QPainter</a> p;
int x = 10;
int y = h/2 + fm.<a href="qfontmetrics.html#200b74">descent</a>();
int i = 0;
p.<a href="qpainter.html#02ed5d">begin</a>( &pm );
p.<a href="qpainter.html#998df2">setFont</a>( <a href="qwidget.html#167922">font</a>() );
while ( !t[i].isNull() ) {
int i16 = (b+i) & 15;
p.<a href="qpainter.html#0183e4">setPen</a>( <a href="qcolor.html">QColor</a>((15-i16)*16,255,255,QColor::Hsv) );
p.<a href="qpainter.html#0f088f">drawText</a>( x, y-sin_tbl[i16]*h/800, t.mid(i,1), 1 );
x += fm.<a href="qfontmetrics.html#3b6f39">width</a>( t[i] );
i++;
}
p.<a href="qpainter.html#365784">end</a>();
// 4: Copy the pixmap to the Hello widget
<a href="qpaintdevice.html#35ae2e">bitBlt</a>( this, pmx, pmy, &pm );
}
</pre>
<hr>
Main:
<pre>/****************************************************************************
** $Id: qt/examples/hello/main.cpp 2.3.2 edited 2001-01-26 $
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of an example program for Qt. This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/
#include "hello.h"
#include <<a name="qapplication.h"></a><a href="qapplication-h.html">qapplication.h</a>>
/*
The program starts here. It parses the command line and builds a message
string to be displayed by the Hello widget.
*/
int main( int argc, char **argv )
{
<a name="QApplication"></a><a href="qapplication.html">QApplication</a> a(argc,argv);
<a name="QString"></a><a href="qstring.html">QString</a> s;
for ( int i=1; i<argc; i++ ) {
s += argv[i];
if ( i<argc-1 )
s += " ";
}
if ( s.<a name="isEmpty"></a><a href="qstring.html#c62623">isEmpty</a>() )
s = "Hello, World";
Hello h( s );
h.<a name="setCaption"></a><a href="qwidget.html#d6a291">setCaption</a>( "Qt says hello" );
<a name="QObject::connect"></a><a href="qobject.html#7f8e37">QObject::connect</a>( &h, SIGNAL(clicked()), &a, SLOT(quit()) );
h.<a name="setFont"></a><a href="qwidget.html#090d60">setFont</a>( <a name="QFont"></a><a href="qfont.html">QFont</a>("times",32,QFont::Bold) ); // default font
h.<a name="setBackgroundColor"></a><a href="qwidget.html#c09181">setBackgroundColor</a>( Qt::white ); // default bg color
a.<a name="setMainWidget"></a><a href="qapplication.html#7ad759">setMainWidget</a>( &h );
h.<a name="show"></a><a href="qwidget.html#200ee5">show</a>();
return a.<a name="exec"></a><a href="qapplication.html#84c7bf">exec</a>();
}
</pre>
<p><address><hr><div align="center">
<table width="100%" cellspacing="0" border="0"><tr>
<td>Copyright 2001 Trolltech<td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
<td align="right"><div align="right">Qt version 2.3.2</div>
</table></div></address></body></html>
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