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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Simple Painting Application</h1>
<p>
This example implements the famous scribble example. You can draw around
in the canvas with different pens and save the result as picture.
<p> <hr>
<p> Header file:
<p> <pre>/****************************************************************************
** $Id: qt/scribble.h 3.1.1 edited Nov 8 10:35 $
**
** 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 SCRIBBLE_H
#define SCRIBBLE_H
#include <<a href="qmainwindow-h.html">qmainwindow.h</a>>
#include <<a href="qpen-h.html">qpen.h</a>>
#include <<a href="qpoint-h.html">qpoint.h</a>>
#include <<a href="qpixmap-h.html">qpixmap.h</a>>
#include <<a href="qwidget-h.html">qwidget.h</a>>
#include <<a href="qstring-h.html">qstring.h</a>>
#include <<a href="qpointarray-h.html">qpointarray.h</a>>
class QMouseEvent;
class QResizeEvent;
class QPaintEvent;
class QToolButton;
class QSpinBox;
class Canvas : public <a href="qwidget.html">QWidget</a>
{
<a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
Canvas( <a href="qwidget.html">QWidget</a> *parent = 0, const char *name = 0 );
void setPenColor( const <a href="qcolor.html">QColor</a> &c )
<a name="x919"></a> { pen.<a href="qpen.html#setColor">setColor</a>( c ); }
void setPenWidth( int w )
<a name="x920"></a> { pen.<a href="qpen.html#setWidth">setWidth</a>( w ); }
<a href="qcolor.html">QColor</a> penColor()
<a name="x918"></a> { return pen.<a href="qpen.html#color">color</a>(); }
int penWidth()
<a name="x921"></a> { return pen.<a href="qpen.html#width">width</a>(); }
void save( const <a href="qstring.html">QString</a> &filename, const <a href="qstring.html">QString</a> &format );
void clearScreen();
protected:
void mousePressEvent( <a href="qmouseevent.html">QMouseEvent</a> *e );
void mouseReleaseEvent( <a href="qmouseevent.html">QMouseEvent</a> *e );
void mouseMoveEvent( <a href="qmouseevent.html">QMouseEvent</a> *e );
void resizeEvent( <a href="qresizeevent.html">QResizeEvent</a> *e );
void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> *e );
<a href="qpen.html">QPen</a> pen;
<a href="qpointarray.html">QPointArray</a> polyline;
bool mousePressed;
<a href="qpixmap.html">QPixmap</a> buffer;
};
class Scribble : public <a href="qmainwindow.html">QMainWindow</a>
{
Q_OBJECT
public:
Scribble( <a href="qwidget.html">QWidget</a> *parent = 0, const char *name = 0 );
protected:
Canvas* canvas;
<a href="qspinbox.html">QSpinBox</a> *bPWidth;
<a href="qtoolbutton.html">QToolButton</a> *bPColor, *bSave, *bClear;
protected slots:
void slotSave();
void slotColor();
void slotWidth( int );
void slotClear();
};
#endif
</pre>
<p> <hr>
<p> Implementation:
<p> <pre>/****************************************************************************
** $Id: qt/scribble.cpp 3.1.1 edited Nov 8 10:35 $
**
** 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 "scribble.h"
#include <<a href="qapplication-h.html">qapplication.h</a>>
#include <<a href="qevent-h.html">qevent.h</a>>
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qtoolbar-h.html">qtoolbar.h</a>>
#include <<a href="qtoolbutton-h.html">qtoolbutton.h</a>>
#include <<a href="qspinbox-h.html">qspinbox.h</a>>
#include <<a href="qtooltip-h.html">qtooltip.h</a>>
#include <<a href="qrect-h.html">qrect.h</a>>
#include <<a href="qpoint-h.html">qpoint.h</a>>
#include <<a href="qcolordialog-h.html">qcolordialog.h</a>>
#include <<a href="qfiledialog-h.html">qfiledialog.h</a>>
#include <<a href="qcursor-h.html">qcursor.h</a>>
#include <<a href="qimage-h.html">qimage.h</a>>
#include <<a href="qstrlist-h.html">qstrlist.h</a>>
#include <<a href="qpopupmenu-h.html">qpopupmenu.h</a>>
#include <<a href="qintdict-h.html">qintdict.h</a>>
const bool no_writing = FALSE;
<a name="f343"></a>Canvas::Canvas( <a href="qwidget.html">QWidget</a> *parent, const char *name )
: <a href="qwidget.html">QWidget</a>( parent, name, WStaticContents ), pen( Qt::red, 3 ), polyline(3),
mousePressed( FALSE ), buffer( <a href="qwidget.html#width">width</a>(), height() )
{
<a name="x923"></a><a name="x922"></a> if ((qApp-><a href="qapplication.html#argc">argc</a>() > 0) && !buffer.load(qApp-><a href="qapplication.html#argv">argv</a>()[1]))
buffer.fill( <a href="qwidget.html#colorGroup">colorGroup</a>().base() );
<a href="qwidget.html#setBackgroundMode">setBackgroundMode</a>( QWidget::PaletteBase );
#ifndef QT_NO_CURSOR
<a href="qwidget.html#setCursor">setCursor</a>( Qt::crossCursor );
#endif
}
void <a name="f344"></a>Canvas::save( const <a href="qstring.html">QString</a> &filename, const <a href="qstring.html">QString</a> &format )
{
if ( !no_writing )
<a name="x959"></a> buffer.save( filename, format.<a href="qstring.html#upper">upper</a>() );
}
void <a name="f345"></a>Canvas::clearScreen()
{
buffer.fill( <a href="qwidget.html#colorGroup">colorGroup</a>().base() );
<a href="qwidget.html#repaint">repaint</a>( FALSE );
}
<a name="x965"></a>void Canvas::<a href="qwidget.html#mousePressEvent">mousePressEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> *e )
{
mousePressed = TRUE;
polyline[2] = polyline[1] = polyline[0] = e-><a href="qmouseevent.html#pos">pos</a>();
}
<a name="x966"></a>void Canvas::<a href="qwidget.html#mouseReleaseEvent">mouseReleaseEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> * )
{
mousePressed = FALSE;
}
<a name="x964"></a>void Canvas::<a href="qwidget.html#mouseMoveEvent">mouseMoveEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> *e )
{
if ( mousePressed ) {
<a href="qpainter.html">QPainter</a> painter;
painter.<a href="qpainter.html#begin">begin</a>( &buffer );
painter.<a href="qpainter.html#setPen">setPen</a>( pen );
polyline[2] = polyline[1];
polyline[1] = polyline[0];
polyline[0] = e-><a href="qmouseevent.html#pos">pos</a>();
<a name="x934"></a> painter.<a href="qpainter.html#drawPolyline">drawPolyline</a>( polyline );
painter.<a href="qpainter.html#end">end</a>();
<a href="qrect.html">QRect</a> r = polyline.boundingRect();
<a name="x945"></a> r = r.<a href="qrect.html#normalize">normalize</a>();
<a name="x948"></a><a name="x944"></a> r.<a href="qrect.html#setLeft">setLeft</a>( r.<a href="qrect.html#left">left</a>() - penWidth() );
<a name="x951"></a><a name="x950"></a> r.<a href="qrect.html#setTop">setTop</a>( r.<a href="qrect.html#top">top</a>() - penWidth() );
<a name="x949"></a><a name="x946"></a> r.<a href="qrect.html#setRight">setRight</a>( r.<a href="qrect.html#right">right</a>() + penWidth() );
<a name="x947"></a><a name="x942"></a> r.<a href="qrect.html#setBottom">setBottom</a>( r.<a href="qrect.html#bottom">bottom</a>() + penWidth() );
<a name="x954"></a><a name="x953"></a><a name="x943"></a> <a href="qpaintdevice.html#bitBlt-2">bitBlt</a>( this, r.<a href="qrect.html#x">x</a>(), r.<a href="qrect.html#y">y</a>(), &buffer, r.<a href="qrect.html#x">x</a>(), r.<a href="qrect.html#y">y</a>(), r.<a href="qrect.html#width">width</a>(), r.<a href="qrect.html#height">height</a>() );
}
}
<a name="x968"></a>void Canvas::<a href="qwidget.html#resizeEvent">resizeEvent</a>( <a href="qresizeevent.html">QResizeEvent</a> *e )
{
QWidget::<a href="qwidget.html#resizeEvent">resizeEvent</a>( e );
int w = <a href="qwidget.html#width">width</a>() > buffer.width() ?
<a href="qwidget.html#width">width</a>() : buffer.width();
int h = <a href="qwidget.html#height">height</a>() > buffer.height() ?
<a href="qwidget.html#height">height</a>() : buffer.height();
<a href="qpixmap.html">QPixmap</a> tmp( buffer );
buffer.resize( w, h );
buffer.fill( <a href="qwidget.html#colorGroup">colorGroup</a>().base() );
<a name="x939"></a><a name="x938"></a> <a href="qpaintdevice.html#bitBlt-2">bitBlt</a>( &buffer, 0, 0, &tmp, 0, 0, tmp.<a href="qpixmap.html#width">width</a>(), tmp.<a href="qpixmap.html#height">height</a>() );
}
<a name="x967"></a>void Canvas::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> *e )
{
QWidget::<a href="qwidget.html#paintEvent">paintEvent</a>( e );
<a name="x937"></a> <a href="qmemarray.html">QMemArray</a><QRect> rects = e-><a href="qpaintevent.html#region">region</a>().rects();
<a name="x930"></a> for ( uint i = 0; i < rects.<a href="qmemarray.html#count">count</a>(); i++ ) {
<a href="qrect.html">QRect</a> r = rects[(int)i];
<a href="qpaintdevice.html#bitBlt-2">bitBlt</a>( this, r.<a href="qrect.html#x">x</a>(), r.<a href="qrect.html#y">y</a>(), &buffer, r.<a href="qrect.html#x">x</a>(), r.<a href="qrect.html#y">y</a>(), r.<a href="qrect.html#width">width</a>(), r.<a href="qrect.html#height">height</a>() );
}
}
//------------------------------------------------------
<a name="f346"></a>Scribble::Scribble( <a href="qwidget.html">QWidget</a> *parent, const char *name )
: <a href="qmainwindow.html">QMainWindow</a>( parent, name )
{
canvas = new Canvas( this );
<a href="qmainwindow.html#setCentralWidget">setCentralWidget</a>( canvas );
<a href="qtoolbar.html">QToolBar</a> *tools = new <a href="qtoolbar.html">QToolBar</a>( this );
bSave = new <a href="qtoolbutton.html">QToolButton</a>( QPixmap(), "Save", "Save as PNG image", this, SLOT( slotSave() ), tools );
<a name="x924"></a> bSave-><a href="qbutton.html#setText">setText</a>( "Save as..." );
<a name="x960"></a> tools-><a href="qtoolbar.html#addSeparator">addSeparator</a>();
bPColor = new <a href="qtoolbutton.html">QToolButton</a>( QPixmap(), "Choose Pen Color", "Choose Pen Color", this, SLOT( slotColor() ), tools );
bPColor-><a href="qbutton.html#setText">setText</a>( "Choose Pen Color..." );
tools-><a href="qtoolbar.html#addSeparator">addSeparator</a>();
bPWidth = new <a href="qspinbox.html">QSpinBox</a>( 1, 20, 1, tools );
<a name="x961"></a> QToolTip::<a href="qtooltip.html#add">add</a>( bPWidth, "Choose Pen Width" );
<a name="x956"></a> <a href="qobject.html#connect">connect</a>( bPWidth, SIGNAL( <a href="qspinbox.html#valueChanged">valueChanged</a>( int ) ), this, SLOT( slotWidth( int ) ) );
<a name="x955"></a> bPWidth-><a href="qspinbox.html#setValue">setValue</a>( 3 );
tools-><a href="qtoolbar.html#addSeparator">addSeparator</a>();
bClear = new <a href="qtoolbutton.html">QToolButton</a>( QPixmap(), "Clear Screen", "Clear Screen", this, SLOT( slotClear() ), tools );
bClear-><a href="qbutton.html#setText">setText</a>( "Clear Screen" );
}
void <a name="f347"></a>Scribble::slotSave()
{
<a href="qpopupmenu.html">QPopupMenu</a> *menu = new <a href="qpopupmenu.html">QPopupMenu</a>( 0 );
<a href="qintdict.html">QIntDict</a><QString> formats;
<a name="x941"></a> formats.<a href="qptrcollection.html#setAutoDelete">setAutoDelete</a>( TRUE );
for ( unsigned int i = 0; i < QImageIO::<a href="qimageio.html#outputFormats">outputFormats</a>().count(); i++ ) {
<a name="x928"></a> <a href="qstring.html">QString</a> str = QString( QImageIO::<a href="qimageio.html#outputFormats">outputFormats</a>().at( i ) );
<a name="x929"></a> formats.<a href="qintdict.html#insert">insert</a>( menu-><a href="qmenudata.html#insertItem">insertItem</a>( QString( "%1..." ).arg( str ) ), new <a href="qstring.html">QString</a>( str ) );
}
<a name="x969"></a> menu-><a href="qwidget.html#setMouseTracking">setMouseTracking</a>( TRUE );
<a name="x963"></a><a name="x962"></a><a name="x940"></a> int id = menu-><a href="qpopupmenu.html#exec">exec</a>( bSave-><a href="qwidget.html#mapToGlobal">mapToGlobal</a>( QPoint( 0, bSave-><a href="qwidget.html#height">height</a>() + 1 ) ) );
if ( id != -1 ) {
<a href="qstring.html">QString</a> format = *formats[ id ];
<a name="x958"></a> <a href="qstring.html">QString</a> filename = QFileDialog::<a href="qfiledialog.html#getSaveFileName">getSaveFileName</a>( <a href="qstring.html#QString-null">QString::null</a>, QString( "*.%1" ).arg( format.<a href="qstring.html#lower">lower</a>() ), this );
if ( !filename.<a href="qstring.html#isEmpty">isEmpty</a>() )
canvas->save( filename, format );
}
delete menu;
}
void <a name="f348"></a>Scribble::slotColor()
{
<a name="x926"></a> <a href="qcolor.html">QColor</a> c = QColorDialog::<a href="qcolordialog.html#getColor">getColor</a>( canvas->penColor(), this );
<a name="x925"></a> if ( c.<a href="qcolor.html#isValid">isValid</a>() )
canvas->setPenColor( c );
}
void <a name="f349"></a>Scribble::slotWidth( int w )
{
canvas->setPenWidth( w );
}
void <a name="f350"></a>Scribble::slotClear()
{
canvas->clearScreen();
}
</pre>
<p> <hr>
<p> Main:
<p> <pre>/****************************************************************************
** $Id: qt/main.cpp 3.1.1 edited Nov 8 10:35 $
**
** 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 "scribble.h"
#include <<a href="qapplication-h.html">qapplication.h</a>>
int main( int argc, char **argv )
{
<a href="qapplication.html">QApplication</a> a( argc, argv );
Scribble scribble;
scribble.<a href="qwidget.html#resize">resize</a>( 500, 350 );
scribble.<a href="qwidget.html#setCaption">setCaption</a>("Qt Example - Scribble");
a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &scribble );
<a name="x970"></a> if ( QApplication::<a href="qapplication.html#desktop">desktop</a>()->width() > 550
&& QApplication::<a href="qapplication.html#desktop">desktop</a>()->height() > 366 )
scribble.<a href="qwidget.html#show">show</a>();
else
<a name="x976"></a> scribble.<a href="qwidget.html#showMaximized">showMaximized</a>();
return a.<a href="qapplication.html#exec">exec</a>();
}
</pre>
<p>See also <a href="examples.html">Examples</a>.
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<a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
<td align=right><div align=right>Qt version 3.1.1</div>
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