<!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 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>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 <<a href="qimage-h.html">qimage.h</a>> #include <<a href="qbitmap-h.html">qbitmap.h</a>> #include <<a href="qpainter-h.html">qpainter.h</a>> #include <<a href="qapplication-h.html">qapplication.h</a>> #include <<a href="qdropsite-h.html">qdropsite.h</a>> #include <<a href="qdragobject-h.html">qdragobject.h</a>> #include <stdio.h> 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()&0x7fff % velmax)/3 + velmin; else i = (kindaRand()&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-><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-><a href="qwidget.html#rect">rect</a>(); // desktop rectangle int i; for ( i=0; i<maxcurves; i++ ) a[i].resize( maxpoints ); p = &a[0]; for ( i=0; i<maxpoints; i++ ) { // setup first polygon points <a name="x1756"></a> p->setPoint( i, (kindaRand()&0x7fff) % r.<a href="qrect.html#width">width</a>(), <a name="x1749"></a> (kindaRand()&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<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 >= 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 = &a[head]; if ( ++head >= maxcurves ) head = 0; for ( i=0; i<maxpoints; i++ ) { // calc new curve p->point( i, &x, &y ); x += xvel[i]; y += yvel[i]; if ( x >= maxx ) { x = maxx - (x - maxx + 1); xvel[i] = -velocity(i); } if ( x <= minx ) { x = minx + (minx - x + 1); xvel[i] = velocity(i); } if ( y >= maxy ) { y = maxy - (y - maxy + 1); yvel[i] = -velocity(i); } if ( y <= 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<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<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<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<=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-><a href="qwidget.html#setBackgroundPixmap">setBackgroundPixmap</a>( rpm ); // set desktop pixmap <a name="x1763"></a> d-><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> &c1, const <a href="qcolor.html">QColor</a> &c2, const <a href="qcolor.html">QColor</a> &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 < pm-><a href="qpixmap.html#width">width</a>() ; i++ ) <a name="x1743"></a> for( int j = 0 ; j < pm-><a href="qpixmap.html#height">height</a>() ; j++ ) { int r = kindaRand(); if ( r < KINDA_RAND_MAX / 3 ) <a name="x1741"></a> p.<a href="qpainter.html#setPen">setPen</a>( p1 ); else if ( r < 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> &topColor, const <a href="qcolor.html">QColor</a> &bottomColor, int sw = 2 ) { <a name="x1739"></a> if ( !p-><a href="qpainter.html#isActive">isActive</a>() ) return; p-><a href="qpainter.html#setPen">setPen</a>( bottomColor ); <a name="x1736"></a> p-><a href="qpainter.html#drawText">drawText</a>( x+sw, y+sw, text ); p-><a href="qpainter.html#setPen">setPen</a>( topColor ); p-><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-><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-><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>( &offscreen ); <a name="x1758"></a><a name="x1757"></a> drawShadeText( &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, &offscreen ); } void desktopWidget( const char *s = "Trolltech" ) { DesktopWidget *t = new DesktopWidget(s); t-><a href="qwidget.html#update">update</a>(); qApp-><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-><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>( &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-><a href="qapplication.html#desktop">desktop</a>()->width(); int appHeight = qApp-><a href="qapplication.html#desktop">desktop</a>()->height(); if ( r.<a href="qrect.html#width">width</a>() > 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>() > 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( &pm, c1, c2, c3 ); p.<a href="qpainter.html#begin">begin</a>( &pm ); drawShadeText( &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-><a href="qapplication.html#desktop">desktop</a>()->setBackgroundPixmap( pm ); } // // The program starts here. // int main( int argc, char **argv ) { <a href="qapplication.html">QApplication</a> app( argc, argv ); if ( argc > 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 <text>" "\n\tdesktop -shadewidget <text>\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 © 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>