C++/Qt/QPainter

Circle Widget with paint

  

Foundations of Qt Development\Chapter07\widgets\events\circlewidget.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include "circlewidget.h"
#include <QPainter>
#include <QMouseEvent>
#include <QTimer>
CircleWidget::CircleWidget( QWidget *parent ) : QWidget( parent )
{
  r = 0;
  
  timer = new QTimer( this );
  timer->setInterval( 50 );
  
  connect( timer, SIGNAL(timeout()), this, SLOT(timeout()) );
}
QSize CircleWidget::sizeHint() const
{
  return QSize( 200, 200 );
}
void CircleWidget::timeout()
{
  if( r == 0 )
  {
    x = mx;
    y = my;
    
    color = QColor( qrand()%256, qrand()%256, qrand()%256 );
  }
  int dx = mx-x;
  int dy = my-y;
  if( dx*dx+dy*dy <= r*r )
    r++;
  else
    r--;
    
  update();
}
void CircleWidget::paintEvent( QPaintEvent* )
{
  if( r > 0 )
  {
    QPainter painter( this );
    
    painter.setRenderHint( QPainter::Antialiasing );
    
    painter.setPen( color );
    painter.setBrush( color );
    painter.drawEllipse( x-r, y-r, 2*r, 2*r );
  }
}
void CircleWidget::mousePressEvent( QMouseEvent *e )
{
  mx = e->x();
  my = e->y();
  
  timer->start();
}
void CircleWidget::mouseMoveEvent( QMouseEvent *e )
{
  mx = e->x();
  my = e->y();
}
void CircleWidget::mouseReleaseEvent( QMouseEvent *e )
{
  timer->stop();
}

Foundations of Qt Development\Chapter07\widgets\events\circlewidget.h
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#ifndef CIRCLEWIDGET_H
#define CIRCLEWIDGET_H
#include <QWidget>
class QTimer;
class CircleWidget : public QWidget
{
  Q_OBJECT
  
public:
  CircleWidget( QWidget *parent=0 );
  
  QSize sizeHint() const;
private slots:
  void timeout();
  
protected:
  void paintEvent( QPaintEvent* );
  
  void mousePressEvent( QMouseEvent* );
  void mouseMoveEvent( QMouseEvent* );
  void mouseReleaseEvent( QMouseEvent* );
  
private:
  int x, y, r;
  QColor color;
  int mx, my;
  
  QTimer *timer;
};
#endif

Foundations of Qt Development\Chapter07\widgets\events\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include "circlewidget.h"
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  CircleWidget widget;
  widget.show();
  
  return app.exec();
}

Draws a filled-in circle

  
#include <QtGui>
int main(int argc, char* argv[])
{
  QApplication app(argc, argv);
  QPixmap pm(100,100);
  pm.fill();
  QPainter p(&pm);
  p.setRenderHint(QPainter::Antialiasing, true);
  QPen pen(Qt::blue, 2);
  p.setPen(pen);
  QBrush brush(Qt::green);
  p.setBrush(brush);
  p.drawEllipse(10, 10, 80, 80);
  QLabel l;
  l.setPixmap(pm);
  l.show();
  return app.exec();
}

Draw text

  
Foundations of Qt Development\Chapter07\text\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QPixmap>
#include <QPainter>
#include <QTextDocument>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QPixmap pixmap( 200, 330 );
  pixmap.fill( Qt::white );
  QPainter painter( &pixmap );
  painter.setPen( Qt::black );
    
  QPoint point = QPoint( 10, 20 );
  painter.drawText( point, "You can draw text from a point..." );
  painter.drawLine( point+QPoint(-5, 0), point+QPoint(5, 0) );
  painter.drawLine( point+QPoint(0, -5), point+QPoint(0, 5) );
  
  QRect rect = QRect(10, 30, 180, 20);
  painter.drawText( rect, Qt::AlignCenter, 
                    "...or you can draw it inside a rectangle." );
  painter.drawRect( rect );
  
  rect.translate( 0, 30 );
  
  QFont font = QApplication::font();
  font.setPixelSize( rect.height() );
  painter.setFont( font );
  
  painter.drawText( rect, Qt::AlignRight, "Right." );
  painter.drawText( rect, Qt::AlignLeft, "Left." );
  painter.drawRect( rect );
  
  rect.translate( 0, rect.height()+10 );
  rect.setHeight( QFontMetrics( font ).height() );
  painter.drawText( rect, Qt::AlignRight, "Right." );
  painter.drawText( rect, Qt::AlignLeft, "Left." );
  painter.drawRect( rect );
  
  QTextDocument doc;
  doc.setHtml( "<p>A QTextDocument can be used to present formatted text "
               "in a nice way.</p>"
               "<p align=center>It can be <b>formatted</b> "
               "<font size=+2>in</font> <i>different</i> ways.</p>"
               "<p>The text can be really long and contain many "
               "paragraphs. It is properly wrapped and such...</p>" );
  rect.translate( 0, rect.height()+10 );
  rect.setHeight( 160 );
  doc.setTextWidth( rect.width() );
  painter.save();
  painter.translate( rect.topLeft() );
  doc.drawContents( &painter, rect.translated( -rect.topLeft() ) );
  painter.restore();
  painter.drawRect( rect );
  rect.translate( 0, 160 );
  rect.setHeight( doc.size().height()-160 );
  painter.setBrush( Qt::gray );
  painter.drawRect( rect );
  pixmap.save( "text.png" );
  return 0;
}

Linear Gradient

  
#include <QtGui>
int main(int argv, char **args)
{
    QApplication app(argv, args);
    QLinearGradient linearGrad(QPointF(100, 100), QPointF(200, 200));
    linearGrad.setColorAt(0, Qt::black);
    linearGrad.setColorAt(1, Qt::white);
    
    QBrush brush(linearGrad);
    QWidget widget;
    QPalette palette;
    palette.setBrush(widget.backgroundRole(), brush);
    widget.setPalette(palette);
    widget.show();
    return app.exec();
}

Matrix based translation

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
#include <cmath>
class SimpleTransformation : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void SimpleTransformation::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    painter.rotate(45);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QMatrix");
}

class CombinedTransformation : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void CombinedTransformation::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    QMatrix matrix;
    matrix.translate(50, 50);
    matrix.rotate(45);
    matrix.scale(0.5, 1.0);
    painter.setMatrix(matrix);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QMatrix");
}

class BasicOperations : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void BasicOperations::paintEvent(QPaintEvent *)
{
    double pi = 3.14;
    double a    = pi/180 * 45.0;
    double sina = sin(a);
    double cosa = cos(a);
    QMatrix translationMatrix(1, 0, 0, 1, 50.0, 50.0);
    QMatrix rotationMatrix(cosa, sina, -sina, cosa, 0, 0);
    QMatrix scalingMatrix(0.5, 0, 0, 1.0, 0, 0);
    QMatrix matrix;
    matrix =  scalingMatrix * rotationMatrix * translationMatrix;
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    painter.setMatrix(matrix);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QMatrix");
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QWidget widget;
    SimpleTransformation *simpleWidget = new SimpleTransformation;
    CombinedTransformation *combinedWidget = new CombinedTransformation;
    BasicOperations *basicWidget = new BasicOperations;
    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(simpleWidget);
    layout->addWidget(combinedWidget);
    layout->addWidget(basicWidget);
    widget.setLayout(layout);
    widget.show();
    widget.resize(130, 350);
    return app.exec();
}

Painter

  
#include <QtGui>
int main(int argv, char **args)
{
    QApplication app(argv, args);
    QLinearGradient linearGrad(QPointF(100, 100), QPointF(200, 200));
    linearGrad.setColorAt(0, Qt::black);
    linearGrad.setColorAt(1, Qt::white);
    QBrush brush(linearGrad);
        QPainter painter;
        painter.setBrush(brush);          // set the yellow brush
        painter.setPen(Qt::NoPen);        // do not draw outline
        painter.drawRect(40,30, 200,100); // draw filled rectangle
        painter.setBrush(Qt::NoBrush);    // do not fill
        painter.setPen(Qt::black);            // set black pen, 0 pixel width
        painter.drawRect(10,10, 30,20);   // draw rectangle outline
        painter.end();                    // painting done
    QWidget widget;
    QPalette palette;
    palette.setBrush(widget.backgroundRole(), brush);
    widget.setPalette(palette);
    widget.show();
    return app.exec();
}

Painter path

  

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QImage image(100, 100, QImage::Format_RGB32);
    QPainterPath path;
    path.addRect(20, 20, 60, 60);
    path.moveTo(0, 0);
    path.cubicTo(99, 0,  50, 50,  99, 99);
    path.cubicTo(0, 99,  50, 50,  0, 0);
    QPainter painter(&image);
    painter.fillRect(0, 0, 100, 100, Qt::white);
    painter.save();
    painter.translate(0.5, 0.5);
    painter.setPen(QPen(QColor(79, 106, 25), 1, Qt::SolidLine, Qt::FlatCap, Qt::MiterJoin));
    painter.setBrush(QColor(122, 163, 39));
    painter.setRenderHint(QPainter::Antialiasing);
    painter.drawPath(path);
    painter.restore();
    painter.end();
    QLabel lab;
    lab.setPixmap(QPixmap::fromImage(image));
    lab.show();
    return app.exec();
}

Paint picture

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
void myProcessing(const QString &)
{
}
int main()
{
    QWidget myWidget;
    {
        // RECORD
        QPicture picture;
        QPainter painter;
        painter.begin(&picture);           // paint in picture
        painter.drawEllipse(10,20, 80,70); // draw an ellipse
        painter.end();                     // painting done
        picture.save("drawing.pic");       // save picture
    }
    {
        // REPLAY
        QPicture picture;
        picture.load("drawing.pic");           // load picture
        QPainter painter;
        painter.begin(&myImage);               // paint in myImage
        painter.drawPicture(0, 0, picture);    // draw the picture at (0,0)
        painter.end();                         // painting done
    }
    QPicture myPicture;
    {
        // FORMATS
        QStringList list = QPicture::inputFormatList();
        foreach (QString string, list)
            myProcessing(string);
    }
    {
        // OUTPUT
        QStringList list = QPicture::outputFormatList();
        foreach (QString string, list)
            myProcessing(string);
    }
    {
        // PIC READ
        QPictureIO iio;
        QPixmap  pixmap;
        iio.setFileName("vegeburger.pic");
        if (iio.read()) {        // OK
            QPicture picture = iio.picture();
            QPainter painter(&pixmap);
            painter.drawPicture(0, 0, picture);
        }
    }
    {
        QPixmap pixmap;
        // PIC WRITE
        QPictureIO iio;
        QPicture   picture;
        QPainter painter(&picture);
        painter.drawPixmap(0, 0, pixmap);
        iio.setPicture(picture);
        iio.setFileName("vegeburger.pic");
        iio.setFormat("PIC");
        if (iio.write())
            return true; // returned true if written successfully
    }
}

Paint rectangle

  
Foundations of Qt Development\Chapter05\bardelegate\bardelegate.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QPainter>
#include <QModelIndex>
#include "bardelegate.h"
BarDelegate::BarDelegate( QObject *parent ) : QAbstractItemDelegate( parent ) { }
void BarDelegate::paint( QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  if( option.state & QStyle::State_Selected )
    painter->fillRect( option.rect, option.palette.highlight() );
  int value = index.model()->data( index, Qt::DisplayRole ).toInt();
  double factor = double(value)/100.0;
  
  painter->save();
  if( factor > 1 )
  {
    painter->setBrush( Qt::red );
    factor = 1;
  }
  else
    painter->setBrush( QColor( 0, int(factor*255), 255-int(factor*255) ) );
  painter->setPen( Qt::black );
  painter->drawRect( option.rect.x()+2, option.rect.y()+2, int(factor*(option.rect.width()-5)), option.rect.height()-5 );
  painter->restore();
}
QSize BarDelegate::sizeHint( const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  return QSize( 45, 15 ); 
}

Foundations of Qt Development\Chapter05\bardelegate\bardelegate.h
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#ifndef BARDELEGATE_H
#define BARDELEGATE_H
#include <QAbstractItemDelegate>
class BarDelegate : public QAbstractItemDelegate
{
public:
  BarDelegate( QObject *parent = 0 );
  void paint( QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index ) const;
  QSize sizeHint( const QStyleOptionViewItem &option, const QModelIndex &index ) const;
};
#endif // BARDELEGATE_H

Foundations of Qt Development\Chapter05\bardelegate\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QTableView>
#include <QStandardItemModel>
#include "bardelegate.h"
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  QTableView table;
  QStandardItemModel model( 10, 2 ); 
  for( int r=0; r<10; ++r )
  {
    QStandardItem *item = new QStandardItem( QString("Row %1").arg(r+1) );
    item->setEditable( false ); 
    model.setItem( r, 0, item );
    
    model.setItem( r, 1, new QStandardItem( QString::number((r*30)%100 )) );  
  }
  table.setModel( &model );
  
  BarDelegate delegate;
  table.setItemDelegateForColumn( 1, &delegate );
  table.show();
  
  return app.exec();
}

QConicalGradient

  

Foundations of Qt Development\Chapter07\brushgradients\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QPainter>
#include <QBrush>
#include <QPixmap>
void createBrushShot( QBrush brush, QString name )
{
  QPixmap pixmap( 200, 200 );
  pixmap.fill( Qt::white );
  
  QPainter painter( &pixmap );
  
  painter.setBrush( brush );
  painter.drawRect( pixmap.rect() );
  
  pixmap.save( QString("%1.png").arg( name ) );
}
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  QLinearGradient linGrad( QPointF(80, 80), QPoint( 120, 120 ) );
  linGrad.setColorAt( 0, Qt::black );
  linGrad.setColorAt( 1, Qt::white );
    
  linGrad.setSpread( QGradient::PadSpread );
  createBrushShot( QBrush( linGrad ), "LinearPad" );
  linGrad.setSpread( QGradient::RepeatSpread );
  createBrushShot( QBrush( linGrad ), "LinearRepeat" );
  linGrad.setSpread( QGradient::ReflectSpread );
  createBrushShot( QBrush( linGrad ), "LinearReflect" );  
  QRadialGradient radGrad( QPointF(100, 100), 30 );
  radGrad.setColorAt( 0, Qt::black );
  radGrad.setColorAt( 1, Qt::white );
  
  radGrad.setSpread( QGradient::PadSpread );
  createBrushShot( QBrush( radGrad ), "RadialPad" );
  radGrad.setSpread( QGradient::RepeatSpread );
  createBrushShot( QBrush( radGrad ), "RadialRepeat" );
  radGrad.setSpread( QGradient::ReflectSpread );
  createBrushShot( QBrush( radGrad ), "RadialReflect" );
  
  QConicalGradient conGrad( QPointF(100, 100), -45.0 );
  conGrad.setColorAt( 0, Qt::black );
  conGrad.setColorAt( 1, Qt::white );
  
  conGrad.setSpread( QGradient::PadSpread );
  createBrushShot( QBrush( conGrad ), "ConicalPad" );
  conGrad.setSpread( QGradient::RepeatSpread );
  createBrushShot( QBrush( conGrad ), "ConicalRepeat" );
  conGrad.setSpread( QGradient::ReflectSpread );
  createBrushShot( QBrush( conGrad ), "ConicalReflect" );
  
  QBrush textureBrush( QImage("texture.png") );
  createBrushShot( textureBrush, "TextureBrush" );
  
  return 0;
}

QLinearGradient and QPainter

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef PAINTWIDGET_H
#define PAINTWIDGET_H
#include <QWidget>
class QPaintEvent;
class PaintWidget : public QWidget
{
    Q_OBJECT
public:
    PaintWidget(QWidget *parent = 0);
protected:
    void paintEvent(QPaintEvent *event);
};
#endif


#include <QtGui>
#include "paintwidget.h"
PaintWidget::PaintWidget(QWidget *parent)
    : QWidget(parent)
{
}
void PaintWidget::paintEvent(QPaintEvent *event)
{
    QLinearGradient gradient1(rect().topLeft(), rect().bottomRight());
    gradient1.setColorAt(0, QColor("#ffffcc"));
    gradient1.setColorAt(1, QColor("#ccccff"));
    QRectF ellipseRect(width()*0.25, height()*0.25, width()*0.5, height()*0.5);
    QLinearGradient gradient2(ellipseRect.topLeft(), ellipseRect.bottomRight());
    gradient2.setColorAt(0, QColor("#ccccff"));
    gradient2.setColorAt(1, QColor("#ffffcc"));
    QPainter painter;
    painter.begin(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.fillRect(rect(), QBrush(gradient1));
    painter.setBrush(QBrush(gradient2));
    painter.drawEllipse(ellipseRect);
    painter.end();
}


#include <QtGui>
#include "paintwidget.h"
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    PaintWidget window;
    window.show();
    return app.exec();
}

Renderer pattern

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef CLIPWINDOW_H
#define CLIPWINDOW_H
#include <QMainWindow>
class QClipboard;
class QComboBox;
class QLabel;
class QListWidget;
class QMimeData;
class QWidget;
class ClipWindow : public QMainWindow
{
    Q_OBJECT
public:
    ClipWindow(QWidget *parent = 0);
public slots:
    void updateClipboard();
    void updateData(const QString &format);
private:
    int currentItem;
    QClipboard *clipboard;
    QComboBox *mimeTypeCombo;
    QLabel *dataInfoLabel;
    QListWidget *previousItems;
};
#endif






#include <QtGui>
#include "clipwindow.h"
ClipWindow::ClipWindow(QWidget *parent)
    : QMainWindow(parent)
{
    clipboard = QApplication::clipboard();
    QWidget *centralWidget = new QWidget(this);
    QWidget *currentItem = new QWidget(centralWidget);
    QLabel *mimeTypeLabel = new QLabel(tr("MIME types:"), currentItem);
    mimeTypeCombo = new QComboBox(currentItem);
    QLabel *dataLabel = new QLabel(tr("Data:"), currentItem);
    dataInfoLabel = new QLabel("", currentItem);
    previousItems = new QListWidget(centralWidget);
    connect(clipboard, SIGNAL(dataChanged()), this, SLOT(updateClipboard()));
    connect(mimeTypeCombo, SIGNAL(activated(const QString &)),
            this, SLOT(updateData(const QString &)));
    QVBoxLayout *currentLayout = new QVBoxLayout(currentItem);
    currentLayout->addWidget(mimeTypeLabel);
    currentLayout->addWidget(mimeTypeCombo);
    currentLayout->addWidget(dataLabel);
    currentLayout->addWidget(dataInfoLabel);
    currentLayout->addStretch(1);
    QHBoxLayout *mainLayout = new QHBoxLayout(centralWidget);
    mainLayout->addWidget(currentItem, 1);
    mainLayout->addWidget(previousItems);
    setCentralWidget(centralWidget);
    setWindowTitle(tr("Clipboard"));
}

void ClipWindow::updateClipboard()
{
    QStringList formats = clipboard->mimeData()->formats();
    QByteArray data = clipboard->mimeData()->data(format);

    mimeTypeCombo->clear();
    mimeTypeCombo->insertStringList(formats);
    int size = clipboard->mimeData()->data(formats[0]).size();
    QListWidgetItem *newItem = new QListWidgetItem(previousItems);
    newItem->setText(tr("%1 (%2 bytes)").arg(formats[0]).arg(size));
    updateData(formats[0]);
}

void ClipWindow::updateData(const QString &format)
{
    QByteArray data = clipboard->mimeData()->data(format);
    dataInfoLabel->setText(tr("%1 bytes").arg(data.size()));
}




#include <QApplication>
#include "clipwindow.h"
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    ClipWindow *window = new ClipWindow;
    window->resize(640, 480);
    window->show();
    return app.exec();
}

Set pen and brush for QPainter

  
Foundations of Qt Development\Chapter07\penbrush\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QPixmap>
#include <QPainter>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QPixmap pixmap( 200, 100 );
  QPainter painter( &pixmap );
  
  painter.setPen( Qt::red );
  painter.setBrush( Qt::yellow );
  return 0;
}

Set render hint to QPainter::Antialiasing

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
class MyWidget : public QWidget
{
public:
    MyWidget();
protected:
    void paintEvent(QPaintEvent *);
};
MyWidget::MyWidget()
{
    QPalette palette(MyWidget::palette());
    palette.setColor(backgroundRole(), Qt::white);
    setPalette(palette);
}
void MyWidget::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setPen(Qt::darkGreen);
    painter.drawRect(1, 2, 6, 4);
    painter.setPen(Qt::darkGray);
    painter.drawLine(2, 8, 6, 2);
}
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MyWidget widget;
    widget.show();
    return app.exec();
}

svg viewer

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef SVGVIEW_H
#define SVGVIEW_H
#include <QGraphicsView>
QT_BEGIN_NAMESPACE
class QWheelEvent;
class QPaintEvent;
class QFile;
QT_END_NAMESPACE
class SvgView : public QGraphicsView
{
    Q_OBJECT
public:
    enum RendererType { Native, OpenGL, Image };
    SvgView(QWidget *parent = 0);
    void openFile(const QFile &file);
    void setRenderer(RendererType type = Native);
    void drawBackground(QPainter *p, const QRectF &rect);
public slots:
    void setHighQualityAntialiasing(bool highQualityAntialiasing);
    void setViewBackground(bool enable);
    void setViewOutline(bool enable);
protected:
    void wheelEvent(QWheelEvent *event);
    void paintEvent(QPaintEvent *event);
private:
    RendererType m_renderer;
    QGraphicsItem *m_svgItem;
    QGraphicsRectItem *m_backgroundItem;
    QGraphicsRectItem *m_outlineItem;
    QImage m_image;
};
#end



#include "svgview.h"
#include <QFile>
#include <QWheelEvent>
#include <QMouseEvent>
#include <QGraphicsRectItem>
#include <QGraphicsSvgItem>
#include <QPaintEvent>
#include <qmath.h>
#ifndef QT_NO_OPENGL
#include <QGLWidget>
#endif
SvgView::SvgView(QWidget *parent)
    : QGraphicsView(parent)
    , m_renderer(Native)
    , m_svgItem(0)
    , m_backgroundItem(0)
    , m_outlineItem(0)
{
    setScene(new QGraphicsScene(this));
    setTransformationAnchor(AnchorUnderMouse);
    setDragMode(ScrollHandDrag);
    // Prepare background check-board pattern
    QPixmap tilePixmap(64, 64);
    tilePixmap.fill(Qt::white);
    QPainter tilePainter(&tilePixmap);
    QColor color(220, 220, 220);
    tilePainter.fillRect(0, 0, 32, 32, color);
    tilePainter.fillRect(32, 32, 32, 32, color);
    tilePainter.end();
    setBackgroundBrush(tilePixmap);
}
void SvgView::drawBackground(QPainter *p, const QRectF &)
{
    p->save();
    p->resetTransform();
    p->drawTiledPixmap(viewport()->rect(), backgroundBrush().texture());
    p->restore();
}
void SvgView::openFile(const QFile &file)
{
    if (!file.exists())
        return;
    QGraphicsScene *s = scene();
    bool drawBackground = (m_backgroundItem ? m_backgroundItem->isVisible() : false);
    bool drawOutline = (m_outlineItem ? m_outlineItem->isVisible() : true);
    s->clear();
    resetTransform();
    m_svgItem = new QGraphicsSvgItem(file.fileName());
    m_svgItem->setFlags(QGraphicsItem::ItemClipsToShape);
    m_svgItem->setCacheMode(QGraphicsItem::NoCache);
    m_svgItem->setZValue(0);
    m_backgroundItem = new QGraphicsRectItem(m_svgItem->boundingRect());
    m_backgroundItem->setBrush(Qt::white);
    m_backgroundItem->setPen(Qt::NoPen);
    m_backgroundItem->setVisible(drawBackground);
    m_backgroundItem->setZValue(-1);
    m_outlineItem = new QGraphicsRectItem(m_svgItem->boundingRect());
    QPen outline(Qt::black, 2, Qt::DashLine);
    outline.setCosmetic(true);
    m_outlineItem->setPen(outline);
    m_outlineItem->setBrush(Qt::NoBrush);
    m_outlineItem->setVisible(drawOutline);
    m_outlineItem->setZValue(1);
    s->addItem(m_backgroundItem);
    s->addItem(m_svgItem);
    s->addItem(m_outlineItem);
    s->setSceneRect(m_outlineItem->boundingRect().adjusted(-10, -10, 10, 10));
}
void SvgView::setRenderer(RendererType type)
{
    m_renderer = type;
    if (m_renderer == OpenGL) {
#ifndef QT_NO_OPENGL
        setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)));
#endif
    } else {
        setViewport(new QWidget);
    }
}
void SvgView::setHighQualityAntialiasing(bool highQualityAntialiasing)
{
#ifndef QT_NO_OPENGL
    setRenderHint(QPainter::HighQualityAntialiasing, highQualityAntialiasing);
#else
    Q_UNUSED(highQualityAntialiasing);
#endif
}
void SvgView::setViewBackground(bool enable)
{
    if (!m_backgroundItem)
          return;
    m_backgroundItem->setVisible(enable);
}
void SvgView::setViewOutline(bool enable)
{
    if (!m_outlineItem)
        return;
    m_outlineItem->setVisible(enable);
}
void SvgView::paintEvent(QPaintEvent *event)
{
    if (m_renderer == Image) {
        if (m_image.size() != viewport()->size()) {
            m_image = QImage(viewport()->size(), QImage::Format_ARGB32_Premultiplied);
        }
        QPainter imagePainter(&m_image);
        QGraphicsView::render(&imagePainter);
        imagePainter.end();
        QPainter p(viewport());
        p.drawImage(0, 0, m_image);
    } else {
        QGraphicsView::paintEvent(event);
    }
}
void SvgView::wheelEvent(QWheelEvent *event)
{
    qreal factor = qPow(1.2, event->delta() / 240.0);
    scale(factor, factor);
    event->accept();
}




#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QString>
class SvgView;
QT_BEGIN_NAMESPACE
class QAction;
class QGraphicsView;
class QGraphicsScene;
class QGraphicsRectItem;
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    MainWindow();
public slots:
    void openFile(const QString &path = QString());
    void setRenderer(QAction *action);
private:
    QAction *m_nativeAction;
    QAction *m_glAction;
    QAction *m_imageAction;
    QAction *m_highQualityAntialiasingAction;
    QAction *m_backgroundAction;
    QAction *m_outlineAction;
    SvgView *m_view;
    QString m_currentPath;
};
#endif



#include "mainwindow.h"
#include <QtGui>
#include "svgview.h"
MainWindow::MainWindow()
    : QMainWindow()
    , m_view(new SvgView)
{
    QMenu *fileMenu = new QMenu(tr("&File"), this);
    QAction *openAction = fileMenu->addAction(tr("&Open..."));
    openAction->setShortcut(QKeySequence(tr("Ctrl+O")));
    QAction *quitAction = fileMenu->addAction(tr("E&xit"));
    quitAction->setShortcut(QKeySequence(tr("Ctrl+Q")));
    menuBar()->addMenu(fileMenu);
    QMenu *viewMenu = new QMenu(tr("&View"), this);
    m_backgroundAction = viewMenu->addAction(tr("&Background"));
    m_backgroundAction->setEnabled(false);
    m_backgroundAction->setCheckable(true);
    m_backgroundAction->setChecked(false);
    connect(m_backgroundAction, SIGNAL(toggled(bool)), m_view, SLOT(setViewBackground(bool)));
    m_outlineAction = viewMenu->addAction(tr("&Outline"));
    m_outlineAction->setEnabled(false);
    m_outlineAction->setCheckable(true);
    m_outlineAction->setChecked(true);
    connect(m_outlineAction, SIGNAL(toggled(bool)), m_view, SLOT(setViewOutline(bool)));
    menuBar()->addMenu(viewMenu);
    QMenu *rendererMenu = new QMenu(tr("&Renderer"), this);
    m_nativeAction = rendererMenu->addAction(tr("&Native"));
    m_nativeAction->setCheckable(true);
    m_nativeAction->setChecked(true);
#ifndef QT_NO_OPENGL
    m_glAction = rendererMenu->addAction(tr("&OpenGL"));
    m_glAction->setCheckable(true);
#endif
    m_imageAction = rendererMenu->addAction(tr("&Image"));
    m_imageAction->setCheckable(true);
#ifndef QT_NO_OPENGL
    rendererMenu->addSeparator();
    m_highQualityAntialiasingAction = rendererMenu->addAction(tr("&High Quality Antialiasing"));
    m_highQualityAntialiasingAction->setEnabled(false);
    m_highQualityAntialiasingAction->setCheckable(true);
    m_highQualityAntialiasingAction->setChecked(false);
    connect(m_highQualityAntialiasingAction, SIGNAL(toggled(bool)), m_view, SLOT(setHighQualityAntialiasing(bool)));
#endif
    QActionGroup *rendererGroup = new QActionGroup(this);
    rendererGroup->addAction(m_nativeAction);
#ifndef QT_NO_OPENGL
    rendererGroup->addAction(m_glAction);
#endif
    rendererGroup->addAction(m_imageAction);
    menuBar()->addMenu(rendererMenu);
    connect(openAction, SIGNAL(triggered()), this, SLOT(openFile()));
    connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
    connect(rendererGroup, SIGNAL(triggered(QAction *)),
            this, SLOT(setRenderer(QAction *)));
    setCentralWidget(m_view);
    setWindowTitle(tr("SVG Viewer"));
}
void MainWindow::openFile(const QString &path)
{
    QString fileName;
    if (path.isNull())
        fileName = QFileDialog::getOpenFileName(this, tr("Open SVG File"),
                m_currentPath, "SVG files (*.svg *.svgz *.svg.gz)");
    else
        fileName = path;
    if (!fileName.isEmpty()) {
        QFile file(fileName);
        if (!file.exists()) {
            QMessageBox::critical(this, tr("Open SVG File"),
                           QString("Could not open file "%1".").arg(fileName));
            m_outlineAction->setEnabled(false);
            m_backgroundAction->setEnabled(false);
            return;
        }
        m_view->openFile(file);
        if (!fileName.startsWith(":/")) {
            m_currentPath = fileName;
            setWindowTitle(tr("%1 - SVGViewer").arg(m_currentPath));
        }
        m_outlineAction->setEnabled(true);
        m_backgroundAction->setEnabled(true);
        resize(m_view->sizeHint() + QSize(80, 80 + menuBar()->height()));
    }
}
void MainWindow::setRenderer(QAction *action)
{
#ifndef QT_NO_OPENGL
    m_highQualityAntialiasingAction->setEnabled(false);
#endif
    if (action == m_nativeAction)
        m_view->setRenderer(SvgView::Native);
#ifndef QT_NO_OPENGL
    else if (action == m_glAction) {
        m_highQualityAntialiasingAction->setEnabled(true);
        m_view->setRenderer(SvgView::OpenGL);
    }
#endif
    else if (action == m_imageAction) {
        m_view->setRenderer(SvgView::Image);
    }
}



#include <QApplication>
#include <QString>
#ifndef QT_NO_OPENGL
#include <QGLFormat>
#endif
#include "mainwindow.h"
int main(int argc, char **argv)
{
    Q_INIT_RESOURCE(svgviewer);
    QApplication app(argc, argv);
    MainWindow window;
    if (argc == 2)
        window.openFile(argv[1]);
    else
        window.openFile(":/files/bubbles.svg");
    window.show();
    return app.exec();
}

Transformation demo

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef RENDERAREA_H
#define RENDERAREA_H
#include <QFont>
#include <QList>
#include <QPainterPath>
#include <QRect>
#include <QWidget>
QT_BEGIN_NAMESPACE
class QPaintEvent;
QT_END_NAMESPACE

enum Operation { NoTransformation, Translate, Rotate, Scale };

class RenderArea : public QWidget
{
    Q_OBJECT
public:
    RenderArea(QWidget *parent = 0);
    void setOperations(const QList<Operation> &operations);
    void setShape(const QPainterPath &shape);
    QSize minimumSizeHint() const;
    QSize sizeHint() const;
protected:
    void paintEvent(QPaintEvent *event);

private:
    void drawCoordinates(QPainter &painter);
    void drawOutline(QPainter &painter);
    void drawShape(QPainter &painter);
    void transformPainter(QPainter &painter);
    QList<Operation> operations;
    QPainterPath shape;
    QRect xBoundingRect;
    QRect yBoundingRect;
};

#endif



#include <QtGui>
#include "renderarea.h"

RenderArea::RenderArea(QWidget *parent)
    : QWidget(parent)
{
    QFont newFont = font();
    newFont.setPixelSize(12);
    setFont(newFont);
    QFontMetrics fontMetrics(newFont);
    xBoundingRect = fontMetrics.boundingRect(tr("x"));
    yBoundingRect = fontMetrics.boundingRect(tr("y"));
}

void RenderArea::setOperations(const QList<Operation> &operations)
{
    this->operations = operations;
    update();
}

void RenderArea::setShape(const QPainterPath &shape)
{
    this->shape = shape;
    update();
}

QSize RenderArea::minimumSizeHint() const
{
    return QSize(182, 182);
}

QSize RenderArea::sizeHint() const
{
    return QSize(232, 232);
}

void RenderArea::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.fillRect(event->rect(), QBrush(Qt::white));
    painter.translate(66, 66);

    painter.save();
    transformPainter(painter);
    drawShape(painter);
    painter.restore();

    drawOutline(painter);

    transformPainter(painter);
    drawCoordinates(painter);
}

void RenderArea::drawCoordinates(QPainter &painter)
{
    painter.setPen(Qt::red);
    painter.drawLine(0, 0, 50, 0);
    painter.drawLine(48, -2, 50, 0);
    painter.drawLine(48, 2, 50, 0);
    painter.drawText(60 - xBoundingRect.width() / 2,
                     0 + xBoundingRect.height() / 2, tr("x"));
    painter.drawLine(0, 0, 0, 50);
    painter.drawLine(-2, 48, 0, 50);
    painter.drawLine(2, 48, 0, 50);
    painter.drawText(0 - yBoundingRect.width() / 2,
                     60 + yBoundingRect.height() / 2, tr("y"));
}

void RenderArea::drawOutline(QPainter &painter)
{
    painter.setPen(Qt::darkGreen);
    painter.setPen(Qt::DashLine);
    painter.setBrush(Qt::NoBrush);
    painter.drawRect(0, 0, 100, 100);
}

void RenderArea::drawShape(QPainter &painter)
{
    painter.fillPath(shape, Qt::blue);
}

void RenderArea::transformPainter(QPainter &painter)
{
    for (int i = 0; i < operations.size(); ++i) {
        switch (operations[i]) {
        case Translate:
            painter.translate(50, 50);
            break;
        case Scale:
            painter.scale(0.75, 0.75);
            break;
        case Rotate:
            painter.rotate(60);
            break;
        case NoTransformation:
        default:
            ;
        }
    }
}



#ifndef WINDOW_H
#define WINDOW_H
#include <QList>
#include <QPainterPath>
#include <QWidget>
#include "renderarea.h"
QT_BEGIN_NAMESPACE
class QComboBox;
QT_END_NAMESPACE

class Window : public QWidget
{
    Q_OBJECT
public:
    Window();
public slots:
    void operationChanged();
    void shapeSelected(int index);

private:
    void setupShapes();
    enum { NumTransformedAreas = 3 };
    RenderArea *originalRenderArea;
    RenderArea *transformedRenderAreas[NumTransformedAreas];
    QComboBox *shapeComboBox;
    QComboBox *operationComboBoxes[NumTransformedAreas];
    QList<QPainterPath> shapes;
};

#endif



#include <QtGui>
#include "window.h"

Window::Window()
{
    originalRenderArea = new RenderArea;
    shapeComboBox = new QComboBox;
    shapeComboBox->addItem(tr("Clock"));
    shapeComboBox->addItem(tr("House"));
    shapeComboBox->addItem(tr("Text"));
    shapeComboBox->addItem(tr("Truck"));
    QGridLayout *layout = new QGridLayout;
    layout->addWidget(originalRenderArea, 0, 0);
    layout->addWidget(shapeComboBox, 1, 0);

    for (int i = 0; i < NumTransformedAreas; ++i) {
        transformedRenderAreas[i] = new RenderArea;
        operationComboBoxes[i] = new QComboBox;
        operationComboBoxes[i]->addItem(tr("No transformation"));
        operationComboBoxes[i]->addItem(tr("Rotate by 60\xB0"));
        operationComboBoxes[i]->addItem(tr("Scale to 75%"));
        operationComboBoxes[i]->addItem(tr("Translate by (50, 50)"));
        connect(operationComboBoxes[i], SIGNAL(activated(int)),
                this, SLOT(operationChanged()));
        layout->addWidget(transformedRenderAreas[i], 0, i + 1);
        layout->addWidget(operationComboBoxes[i], 1, i + 1);
    }

    setLayout(layout);
    setupShapes();
    shapeSelected(0);
    setWindowTitle(tr("Transformations"));
}

void Window::setupShapes()
{
    QPainterPath truck;
    truck.setFillRule(Qt::WindingFill);
    truck.moveTo(0.0, 87.0);
    truck.lineTo(0.0, 60.0);
    truck.lineTo(10.0, 60.0);
    truck.lineTo(35.0, 35.0);
    truck.lineTo(100.0, 35.0);
    truck.lineTo(100.0, 87.0);
    truck.lineTo(0.0, 87.0);
    truck.moveTo(17.0, 60.0);
    truck.lineTo(55.0, 60.0);
    truck.lineTo(55.0, 40.0);
    truck.lineTo(37.0, 40.0);
    truck.lineTo(17.0, 60.0);
    truck.addEllipse(17.0, 75.0, 25.0, 25.0);
    truck.addEllipse(63.0, 75.0, 25.0, 25.0);

    QPainterPath clock;
    clock.addEllipse(-50.0, -50.0, 100.0, 100.0);
    clock.addEllipse(-48.0, -48.0, 96.0, 96.0);
    clock.moveTo(0.0, 0.0);
    clock.lineTo(-2.0, -2.0);
    clock.lineTo(0.0, -42.0);
    clock.lineTo(2.0, -2.0);
    clock.lineTo(0.0, 0.0);
    clock.moveTo(0.0, 0.0);
    clock.lineTo(2.732, -0.732);
    clock.lineTo(24.495, 14.142);
    clock.lineTo(0.732, 2.732);
    clock.lineTo(0.0, 0.0);

    QPainterPath house;
    house.moveTo(-45.0, -20.0);
    house.lineTo(0.0, -45.0);
    house.lineTo(45.0, -20.0);
    house.lineTo(45.0, 45.0);
    house.lineTo(-45.0, 45.0);
    house.lineTo(-45.0, -20.0);
    house.addRect(15.0, 5.0, 20.0, 35.0);
    house.addRect(-35.0, -15.0, 25.0, 25.0);

    QPainterPath text;
    QFont font;
    font.setPixelSize(50);
    QRect fontBoundingRect = QFontMetrics(font).boundingRect(tr("Qt"));
    text.addText(-QPointF(fontBoundingRect.center()), font, tr("Qt"));

    shapes.append(clock);
    shapes.append(house);
    shapes.append(text);
    shapes.append(truck);
    connect(shapeComboBox, SIGNAL(activated(int)),
            this, SLOT(shapeSelected(int)));
}

void Window::operationChanged()
{
    static const Operation operationTable[] = {
        NoTransformation, Rotate, Scale, Translate
    };
    QList<Operation> operations;
    for (int i = 0; i < NumTransformedAreas; ++i) {
        int index = operationComboBoxes[i]->currentIndex();
        operations.append(operationTable[index]);
        transformedRenderAreas[i]->setOperations(operations);
    }
}

void Window::shapeSelected(int index)
{
    QPainterPath shape = shapes[index];
    originalRenderArea->setShape(shape);
    for (int i = 0; i < NumTransformedAreas; ++i)
        transformedRenderAreas[i]->setShape(shape);
}



#include <QApplication>
#include "window.h"
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Window window;
    window.show();
    return app.exec();
}

Transformed Painter

  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
#include <cmath>
class SimpleTransformation : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void SimpleTransformation::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    painter.rotate(45);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QTransform");
}

class CombinedTransformation : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void CombinedTransformation::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    QTransform transform;
    transform.translate(50, 50);
    transform.rotate(45);
    transform.scale(0.5, 1.0);
    painter.setTransform(transform);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QTransform");
}

class BasicOperations : public QWidget
{
    void paintEvent(QPaintEvent *);
};

void BasicOperations::paintEvent(QPaintEvent *)
{
    double pi = 3.14;
    double a    = pi/180 * 45.0;
    double sina = sin(a);
    double cosa = cos(a);
    QTransform translationTransform(1, 0, 0, 1, 50.0, 50.0);
    QTransform rotationTransform(cosa, sina, -sina, cosa, 0, 0);
    QTransform scalingTransform(0.5, 0, 0, 1.0, 0, 0);
    QTransform transform;
    transform = scalingTransform * rotationTransform * translationTransform;
    QPainter painter(this);
    painter.setPen(QPen(Qt::blue, 1, Qt::DashLine));
    painter.drawRect(0, 0, 100, 100);
    painter.setTransform(transform);
    painter.setFont(QFont("Helvetica", 24));
    painter.setPen(QPen(Qt::black, 1));
    painter.drawText(20, 10, "QTransform");
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QWidget widget;
    SimpleTransformation *simpleWidget = new SimpleTransformation;
    CombinedTransformation *combinedWidget = new CombinedTransformation;
    BasicOperations *basicWidget = new BasicOperations;
    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(simpleWidget);
    layout->addWidget(combinedWidget);
    layout->addWidget(basicWidget);
    widget.setLayout(layout);
    widget.show();
    widget.resize(130, 350);
    return app.exec();
}

Use QPainter to draw arc

  
Foundations of Qt Development\Chapter07\circles\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QPixmap>
#include <QPainter>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QPixmap pixmap( 200, 190 );
  pixmap.fill( Qt::white );
  QPainter painter( &pixmap );
  painter.setRenderHint( QPainter::Antialiasing );
  painter.setPen( Qt::black );
    
  painter.drawEllipse( 10, 10, 10, 80 );
  painter.drawEllipse( 30, 10, 20, 80 );
  painter.drawEllipse( 60, 10, 40, 80 );
  painter.drawEllipse( QRect( 110, 10, 80, 80 ) );
  painter.drawArc( 10, 100, 10, 80, 30*16, 240*16 );
  painter.drawArc( 30, 100, 20, 80, 45*16, 200*16 );
  painter.drawArc( 60, 100, 40, 80, 60*16, 160*16 );
  painter.drawArc( QRect( 110, 100, 80, 80 ), 75*16, 120*16 );
  pixmap.save( "circles.png" );
  return 0;
}

User-draw table

  
Foundations of Qt Development\Chapter05\editdelegate\bardelegate.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QPainter>
#include <QSlider>
#include <QModelIndex>
#include "bardelegate.h"
BarDelegate::BarDelegate( QObject *parent ) : QAbstractItemDelegate( parent ) { }
void BarDelegate::paint( QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  if( option.state & QStyle::State_Selected )
    painter->fillRect( option.rect, option.palette.highlight() );
  int value = index.model()->data( index, Qt::DisplayRole ).toInt();
  double factor = double(value)/100.0;
  
  painter->save();
  if( factor > 1 )
  {
    painter->setBrush( Qt::red );
    factor = 1;
  }
  else
    painter->setBrush( QColor( 0, int(factor*255), 255-int(factor*255) ) );
  painter->setPen( Qt::black );
  painter->drawRect( option.rect.x()+2, option.rect.y()+2, int(factor*(option.rect.width()-5)), option.rect.height()-5 );
  painter->restore();
}
QSize BarDelegate::sizeHint( const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  return QSize( 45, 15 ); 
}
QWidget *BarDelegate::createEditor( QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  QSlider *slider = new QSlider( parent );
  
  slider->setAutoFillBackground( true );
  slider->setOrientation( Qt::Horizontal );
  slider->setRange( 0, 100 );
  slider->installEventFilter( const_cast<BarDelegate*>(this) );
  
  return slider;
}
void BarDelegate::updateEditorGeometry( QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index ) const
{
  editor->setGeometry( option.rect );
}
void BarDelegate::setEditorData( QWidget *editor, const QModelIndex &index ) const
{
  int value = index.model()->data( index, Qt::DisplayRole ).toInt();
  static_cast<QSlider*>( editor )->setValue( value );
}
void BarDelegate::setModelData( QWidget *editor, QAbstractItemModel *model, const QModelIndex &index ) const
{
  model->setData( index, static_cast<QSlider*>( editor )->value() );
}


Foundations of Qt Development\Chapter05\editdelegate\bardelegate.h
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#ifndef BARDELEGATE_H
#define BARDELEGATE_H
#include <QAbstractItemDelegate>
class BarDelegate : public QAbstractItemDelegate
{
public:
  BarDelegate( QObject *parent = 0 );
  void paint( QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index ) const;
  QSize sizeHint( const QStyleOptionViewItem &option, const QModelIndex &index ) const;
  QWidget *createEditor( QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index ) const;
  void setEditorData( QWidget *editor, const QModelIndex &index ) const;
  void setModelData( QWidget *editor, QAbstractItemModel *model, const QModelIndex &index ) const;
  void updateEditorGeometry( QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index ) const;
};
#endif // BARDELEGATE_H

Foundations of Qt Development\Chapter05\editdelegate\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QTableView>
#include <QStandardItemModel>
#include "bardelegate.h"
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  QTableView table;
  QStandardItemModel model( 10, 2 ); 
  for( int r=0; r<10; ++r )
  {
    QStandardItem *item = new QStandardItem( QString("Row %1").arg(r+1) );
    item->setEditable( false ); 
    model.setItem( r, 0, item );
    
    model.setItem( r, 1, new QStandardItem( QString::number((r*30)%100 )) );  
  }
  table.setModel( &model );
  
  BarDelegate delegate;
  table.setItemDelegateForColumn( 1, &delegate );
  table.show();
  
  return app.exec();
}

Using QPainter to draw ellipse

  
Foundations of Qt Development\Chapter07\circles\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QApplication>
#include <QPixmap>
#include <QPainter>
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  QPixmap pixmap( 200, 190 );
  pixmap.fill( Qt::white );
  QPainter painter( &pixmap );
  painter.setRenderHint( QPainter::Antialiasing );
  painter.setPen( Qt::black );
    
  painter.drawEllipse( 10, 10, 10, 80 );
  painter.drawEllipse( 30, 10, 20, 80 );
  painter.drawEllipse( 60, 10, 40, 80 );
  painter.drawEllipse( QRect( 110, 10, 80, 80 ) );
  painter.drawArc( 10, 100, 10, 80, 30*16, 240*16 );
  painter.drawArc( 30, 100, 20, 80, 45*16, 200*16 );
  painter.drawArc( 60, 100, 40, 80, 60*16, 160*16 );
  painter.drawArc( QRect( 110, 100, 80, 80 ), 75*16, 120*16 );
  pixmap.save( "circles.png" );
  return 0;
}

C++/Qt/QPainter

Содержание

Circle Widget with paint

Draws a filled-in circle

Draw text

Linear Gradient

Matrix based translation

Painter

Painter path

Paint picture

Paint rectangle

QConicalGradient

QLinearGradient and QPainter

Renderer pattern

Set pen and brush for QPainter

Set render hint to QPainter::Antialiasing

svg viewer

Transformation demo

Transformed Painter

Use QPainter to draw arc

User-draw table

Using QPainter to draw ellipse

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