/usr/share/qt3/doc/html/desktop-example.html

<!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/examples/desktop/desktop.doc:5 -->
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Painting on the Desktop</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&nbsp;Classes</font></a>
 | <a href="mainclasses.html">
<font color="#004faf">Main&nbsp;Classes</font></a>
 | <a href="annotated.html">
<font color="#004faf">Annotated</font></a>
 | <a href="groups.html">
<font color="#004faf">Grouped&nbsp;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>Painting on the Desktop</h1>

 
<p> 
The desktop demo contains three routines, each of which draws
something on the desktop.  It does some nice stuff with <a href="qpainter.html">QPainter</a>,
and also demonstrates how one can treat the desktop as a widget like
any other.
<p> <hr>
<p> Implementation:
<p> <pre>/****************************************************************************
** $Id: qt/desktop.cpp   3.3.8   edited Jan 11 14:37 $
**
** Copyright (C) 1992-2007 Trolltech ASA.  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 &lt;<a href="qimage-h.html">qimage.h</a>&gt;
#include &lt;<a href="qbitmap-h.html">qbitmap.h</a>&gt;
#include &lt;<a href="qpainter-h.html">qpainter.h</a>&gt;
#include &lt;<a href="qapplication-h.html">qapplication.h</a>&gt;
#include &lt;<a href="qdropsite-h.html">qdropsite.h</a>&gt;
#include &lt;<a href="qdragobject-h.html">qdragobject.h</a>&gt;
#include &lt;stdio.h&gt;


static double seed = 0.353535353535;
static const int KINDA_RAND_MAX = 32767;

static int kindaRand()
{
    seed = seed*147;
    seed = seed - (double) ((int) seed);
    return (int) ( seed*(KINDA_RAND_MAX + 1) );
}

static int velocity( int i )                    // change velocity
{
    const int velmax = 15;
    const int velmin = 4;
    if ( i == 1 || i == 2 )
        i = (kindaRand()&amp;0x7fff % velmax)/3 + velmin;
    else
        i = (kindaRand()&amp;0x7fff % velmax) + velmin;
    return i;
}

//
// Draw polygon on desktop.
//

void poly()
{
<a name="x1721"></a>    <a href="qwidget.html">QWidget</a> *d = QApplication::<a href="qapplication.html#desktop">desktop</a>();
<a name="x1761"></a>    d-&gt;<a href="qwidget.html#setBackgroundColor">setBackgroundColor</a>( Qt::white );         // white desktop

    const int maxpoints = 5;
    const int maxcurves = 8;
    static int xvel[maxpoints];
    static int yvel[maxpoints];
    int head = 0;
    int tail = -maxcurves + 2;
    <a href="qpointarray.html">QPointArray</a> *a = new <a href="qpointarray.html">QPointArray</a>[ maxcurves ];
    register QPointArray *p;
<a name="x1760"></a>    <a href="qrect.html">QRect</a> r = d-&gt;<a href="qwidget.html#rect">rect</a>();                        // desktop rectangle

    int i;
    for ( i=0; i&lt;maxcurves; i++ )
        a[i].resize( maxpoints );
    p = &amp;a[0];
    for ( i=0; i&lt;maxpoints; i++ ) {             // setup first polygon points
<a name="x1756"></a>        p-&gt;setPoint( i, (kindaRand()&amp;0x7fff) % r.<a href="qrect.html#width">width</a>(),
<a name="x1749"></a>                        (kindaRand()&amp;0x7fff) % r.<a href="qrect.html#height">height</a>() );
        xvel[i] = velocity(i);
        yvel[i] = velocity(i);
    }

    <a href="qpainter.html">QPainter</a> paint;
<a name="x1733"></a>    paint.<a href="qpainter.html#begin">begin</a>( d );                           // start painting desktop

    for ( int ntimes=0; ntimes&lt;2000; ntimes++ ) {
        paint.<a href="qpainter.html#setBrush">setBrush</a>( QColor(kindaRand()%360, 180, 255, QColor::Hsv) );
<a name="x1735"></a>        paint.<a href="qpainter.html#drawPolygon">drawPolygon</a>( a[head] );
        if ( ++tail &gt;= maxcurves )
            tail = 0;

<a name="x1751"></a><a name="x1750"></a>        int minx=r.<a href="qrect.html#left">left</a>(), maxx=r.<a href="qrect.html#right">right</a>();
<a name="x1755"></a><a name="x1748"></a>        int miny=r.<a href="qrect.html#top">top</a>(),  maxy=r.<a href="qrect.html#bottom">bottom</a>();
        int x, y;
        p = &amp;a[head];
        if ( ++head &gt;= maxcurves )
            head = 0;
        for ( i=0; i&lt;maxpoints; i++ ) {         // calc new curve
            p-&gt;point( i, &amp;x, &amp;y );
            x += xvel[i];
            y += yvel[i];
            if ( x &gt;= maxx ) {
                x = maxx - (x - maxx + 1);
                xvel[i] = -velocity(i);
            }
            if ( x &lt;= minx ) {
                x = minx + (minx - x + 1);
                xvel[i] = velocity(i);
            }
            if ( y &gt;= maxy ) {
                y = maxy - (y - maxy + 1);
                yvel[i] = -velocity(i);
            }
            if ( y &lt;= miny ) {
                y = miny + (miny - y + 1);
                yvel[i] = velocity(i);
            }
            a[head].setPoint( i, x, y );
        }
    }
<a name="x1737"></a>    paint.<a href="qpainter.html#end">end</a>();                                // painting done
    delete[] a;
}


//
// Rotate pattern on desktop.
//

void rotate()
{
    int i;
    const int w = 64;
    const int h = 64;
    <a href="qimage.html">QImage</a> image( w, h, 8, 128 );               // create image
    for ( i=0; i&lt;128; i++ )                     // build color table
<a name="x1730"></a>        image.<a href="qimage.html#setColor">setColor</a>( i, qRgb(i,0,0) );
    for ( int y=0; y&lt;h; y++ ) {                 // set image pixels
<a name="x1729"></a>        uchar *p = image.<a href="qimage.html#scanLine">scanLine</a>(y);
        for ( int x=0; x&lt;w; x++ )
            *p++ = (x+y)%128;
    }

    <a href="qpixmap.html">QPixmap</a> pm;
    pm = image;                                 // convert image to pixmap
<a name="x1745"></a>    pm.<a href="qpixmap.html#setOptimization">setOptimization</a>( QPixmap::BestOptim );   // rotation will be faster

    <a href="qwidget.html">QWidget</a> *d = QApplication::<a href="qapplication.html#desktop">desktop</a>();       // w = desktop widget

    for ( i=0; i&lt;=360; i += 2 ) {
        <a href="qwmatrix.html">QWMatrix</a> m;
<a name="x1764"></a>        m.<a href="qwmatrix.html#rotate">rotate</a>( i );                          // rotate coordinate system
<a name="x1747"></a>        <a href="qpixmap.html">QPixmap</a> rpm = pm.<a href="qpixmap.html#xForm">xForm</a>( m );            // rpm = rotated pixmap
<a name="x1762"></a>        d-&gt;<a href="qwidget.html#setBackgroundPixmap">setBackgroundPixmap</a>( rpm );          // set desktop pixmap
<a name="x1763"></a>        d-&gt;<a href="qwidget.html#update">update</a>();                            // repaint desktop
    }
}

//
// Generates a marble-like pattern in pm.
//

void generateStone( <a href="qpixmap.html">QPixmap</a> *pm,
                    const <a href="qcolor.html">QColor</a> &amp;c1, const <a href="qcolor.html">QColor</a> &amp;c2, const <a href="qcolor.html">QColor</a> &amp;c3 )
{
    <a href="qpainter.html">QPainter</a> p;
    <a href="qpen.html">QPen</a> p1 ( c1, 0 );
    <a href="qpen.html">QPen</a> p2 ( c2, 0 );
    <a href="qpen.html">QPen</a> p3 ( c3, 0 );

    p.<a href="qpainter.html#begin">begin</a>( pm );
<a name="x1746"></a>    for( int i = 0 ; i &lt; pm-&gt;<a href="qpixmap.html#width">width</a>() ; i++ )
<a name="x1743"></a>        for( int j = 0 ; j &lt; pm-&gt;<a href="qpixmap.html#height">height</a>() ; j++ ) {
            int r = kindaRand();
            if ( r &lt; KINDA_RAND_MAX / 3 )
<a name="x1741"></a>                p.<a href="qpainter.html#setPen">setPen</a>( p1 );
            else if ( r &lt; KINDA_RAND_MAX / 3 * 2 )
                p.<a href="qpainter.html#setPen">setPen</a>( p2 );
            else
                p.<a href="qpainter.html#setPen">setPen</a>( p3 );
<a name="x1734"></a>            p.<a href="qpainter.html#drawPoint">drawPoint</a>( i,j );
        }
    p.<a href="qpainter.html#end">end</a>();
}

void drawShadeText( <a href="qpainter.html">QPainter</a> *p, int x, int y, const char *text,
                    const <a href="qcolor.html">QColor</a> &amp;topColor, const <a href="qcolor.html">QColor</a> &amp;bottomColor,
                    int sw = 2 )
{
<a name="x1739"></a>    if ( !p-&gt;<a href="qpainter.html#isActive">isActive</a>() )
        return;

    p-&gt;<a href="qpainter.html#setPen">setPen</a>( bottomColor );
<a name="x1736"></a>    p-&gt;<a href="qpainter.html#drawText">drawText</a>( x+sw, y+sw, text );
    p-&gt;<a href="qpainter.html#setPen">setPen</a>( topColor );
    p-&gt;<a href="qpainter.html#drawText">drawText</a>( x, y, text );
}

// NOTE: desktop drag/drop is experimental

class DesktopWidget : public <a href="qwidget.html">QWidget</a>, private QDropSite
{
public:
    DesktopWidget( const char *s, QWidget *parent=0, const char *name=0 );
   ~DesktopWidget();
    void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );

    void dragEnterEvent( <a href="qdragenterevent.html">QDragEnterEvent</a> *e )
    {
<a name="x1731"></a>        if ( QImageDrag::<a href="qimagedrag.html#canDecode">canDecode</a>(e) )
<a name="x1727"></a>            e-&gt;<a href="qdragmoveevent.html#accept">accept</a>();
    }

    void dragLeaveEvent( <a href="qdragleaveevent.html">QDragLeaveEvent</a> * )
    {
    }

    void dragMoveEvent( <a href="qdragmoveevent.html">QDragMoveEvent</a> *e )
    {
        e-&gt;<a href="qdragmoveevent.html#accept">accept</a>();
    }

    void dropEvent( <a href="qdropevent.html">QDropEvent</a> * e )
    {
        <a href="qpixmap.html">QPixmap</a> pmp;
<a name="x1732"></a>        if ( QImageDrag::<a href="qimagedrag.html#decode">decode</a>( e, pmp ) ) {
            <a href="qwidget.html#setBackgroundPixmap">setBackgroundPixmap</a>( pmp );
            <a href="qwidget.html#update">update</a>();
        }
    }

private:
    <a href="qpixmap.html">QPixmap</a> *pm;
    <a href="qstring.html">QString</a> text;
};

<a name="f483"></a>DesktopWidget::DesktopWidget( const char *s, QWidget *parent, const char *name )
    : <a href="qwidget.html">QWidget</a>( parent, name, WType_Desktop | WPaintDesktop),
        QDropSite(this)
{
    text = s;
    pm   = 0;
}

DesktopWidget::~DesktopWidget()
{
    delete pm;
}

void DesktopWidget::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
{
    <a href="qcolor.html">QColor</a> c1 = <a href="qwidget.html#backgroundColor">backgroundColor</a>();
<a name="x1726"></a>    <a href="qcolor.html">QColor</a> c2 = c1.<a href="qcolor.html#light">light</a>(104);
<a name="x1725"></a>    <a href="qcolor.html">QColor</a> c3 = c1.<a href="qcolor.html#dark">dark</a>(106);
    if ( !pm ) {
        pm = new <a href="qpixmap.html">QPixmap</a>( 64, 64 );
        generateStone( pm, c1, c2, c3 );
        <a href="qwidget.html#setBackgroundPixmap">setBackgroundPixmap</a>( *pm );
        <a href="qwidget.html#update">update</a>();
    }
    <a href="qrect.html">QRect</a> br = <a href="qwidget.html#fontMetrics">fontMetrics</a>().boundingRect( text );
    <a href="qpixmap.html">QPixmap</a> offscreen( br.<a href="qrect.html#width">width</a>(), br.<a href="qrect.html#height">height</a>() );
    int x = <a href="qwidget.html#width">width</a>()/2  - br.<a href="qrect.html#width">width</a>()/2;
    int y = <a href="qwidget.html#height">height</a>()/2 - br.<a href="qrect.html#height">height</a>()/2;
<a name="x1742"></a>    offscreen.<a href="qpixmap.html#fill">fill</a>( this, x, y );
    <a href="qpainter.html">QPainter</a> p;
    p.<a href="qpainter.html#begin">begin</a>( &amp;offscreen );
<a name="x1758"></a><a name="x1757"></a>    drawShadeText( &amp;p, -br.<a href="qrect.html#x">x</a>(), -br.<a href="qrect.html#y">y</a>(), text, c2, c3, 3 );
    p.<a href="qpainter.html#end">end</a>();
    <a href="qimage.html#bitBlt">bitBlt</a>( this, x, y, &amp;offscreen );
}

void desktopWidget( const char *s = "Trolltech" )
{
    DesktopWidget *t = new DesktopWidget(s);
    t-&gt;<a href="qwidget.html#update">update</a>();
    qApp-&gt;<a href="qapplication.html#exec">exec</a>();
    delete t;
}

void desktopText( const char *s = "Trolltech" )
{
    const int border = 20;

<a name="x1723"></a>    <a href="qcolor.html">QColor</a> c1 =  qApp-&gt;<a href="qapplication.html#palette">palette</a>().inactive().background();
    <a href="qcolor.html">QColor</a> c2 = c1.<a href="qcolor.html#light">light</a>(104);
    <a href="qcolor.html">QColor</a> c3 = c1.<a href="qcolor.html#dark">dark</a>(106);

    <a href="qpixmap.html">QPixmap</a> pm(10,10);

    <a href="qpainter.html">QPainter</a> p;
    p.<a href="qpainter.html#begin">begin</a>( &amp;pm );
<a name="x1738"></a>    <a href="qrect.html">QRect</a> r = p.<a href="qpainter.html#fontMetrics">fontMetrics</a>().boundingRect( s );
    p.<a href="qpainter.html#end">end</a>();

    int appWidth  =  qApp-&gt;<a href="qapplication.html#desktop">desktop</a>()-&gt;width();
    int appHeight =  qApp-&gt;<a href="qapplication.html#desktop">desktop</a>()-&gt;height();
    if ( r.<a href="qrect.html#width">width</a>() &gt; appWidth - border*2 )
<a name="x1753"></a>        r.<a href="qrect.html#setWidth">setWidth</a>( appWidth - border*2 );
    if ( r.<a href="qrect.html#height">height</a>() &gt; appHeight - border*2 )
<a name="x1752"></a>        r.<a href="qrect.html#setHeight">setHeight</a>( appHeight - border*2 );

<a name="x1754"></a><a name="x1744"></a>    pm.<a href="qpixmap.html#resize">resize</a>( r.<a href="qrect.html#size">size</a>() + QSize( border*2, border*2 ) );
    generateStone( &amp;pm, c1, c2, c3 );
    p.<a href="qpainter.html#begin">begin</a>( &amp;pm );
    drawShadeText( &amp;p, -r.<a href="qrect.html#x">x</a>() + border, -r.<a href="qrect.html#y">y</a>() + border, s, c2, c3 );
    p.<a href="qpainter.html#end">end</a>();

    qApp-&gt;<a href="qapplication.html#desktop">desktop</a>()-&gt;setBackgroundPixmap( pm );
}

//
// The program starts here.
//

int main( int argc, char **argv )
{
    <a href="qapplication.html">QApplication</a> app( argc, argv );

    if ( argc &gt; 1 ) {
        <a href="qfont.html">QFont</a> f( "charter", 96, QFont::Black );
<a name="x1728"></a>        f.<a href="qfont.html#setStyleHint">setStyleHint</a>( QFont::Times );
<a name="x1724"></a>        app.<a href="qapplication.html#setFont">setFont</a>( f );
    }

    bool validOptions = FALSE;

    if ( argc == 2 ) {
        validOptions = TRUE;
        if ( strcmp(argv[1],"-poly") == 0 )
            poly();
        else if ( strcmp(argv[1],"-rotate") == 0 )
            rotate();
        else if ( strcmp(argv[1],"-troll") == 0 )
            desktopText();
        else if ( strcmp(argv[1],"-trollwidget") == 0 )
            desktopWidget();
        else
            validOptions = FALSE;
    }
    if ( argc == 3 ) {
        validOptions = TRUE;
        if ( strcmp(argv[1],"-shadetext") == 0 )
            desktopText( argv[2] );
        else if ( strcmp(argv[1],"-shadewidget") == 0 )
            desktopWidget( argv[2] );
        else
            validOptions = FALSE;
    }
    if ( !validOptions ) {
        fprintf( stderr, "Usage:\n\tdesktop -poly"
                               "\n\tdesktop -rotate"
                               "\n\tdesktop -troll"
                               "\n\tdesktop -trollwidget"
                               "\n\tdesktop -shadetext &lt;text&gt;"
                               "\n\tdesktop -shadewidget &lt;text&gt;\n" );
        rotate();
    }
    return 0;
}
</pre>

<p>See also <a href="examples.html">Examples</a>.

<!-- eof -->
<p><address><hr><div align=center>
<table width=100% cellspacing=0 border=0><tr>
<td>Copyright &copy; 2007
<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
<td align=right><div align=right>Qt 3.3.8</div>
</table></div></address></body>
</html>
qt3-doc 3:3.3.8-b-8ubuntu3 / usr / share / qt3 / doc / html / desktop-example.html
