Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# lighting.cpp Example File

effects/lighting/lighting.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "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 The Qt Company Ltd 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."
     **
     ** $QT_END_LICENSE$
     **
     ****************************************************************************/

     #include "lighting.h"

     #include <QtGui>

     #ifndef M_PI
     #define M_PI 3.14159265358979323846
     #endif

     Lighting::Lighting(QWidget *parent): QGraphicsView(parent), angle(0.0)
     {
         setScene(&m_scene);

         setupScene();

         QTimer *timer = new QTimer(this);
         connect(timer, SIGNAL(timeout()), SLOT(animate()));
         timer->setInterval(30);
         timer->start();

         setRenderHint(QPainter::Antialiasing, true);
         setFrameStyle(QFrame::NoFrame);
     }

     void Lighting::setupScene()
     {
         m_scene.setSceneRect(-300, -200, 600, 460);

         QLinearGradient linearGrad(QPointF(-100, -100), QPointF(100, 100));
         linearGrad.setColorAt(0, QColor(255, 255, 255));
         linearGrad.setColorAt(1, QColor(192, 192, 255));
         setBackgroundBrush(linearGrad);

         QRadialGradient radialGrad(30, 30, 30);
         radialGrad.setColorAt(0, Qt::yellow);
         radialGrad.setColorAt(0.2, Qt::yellow);
         radialGrad.setColorAt(1, Qt::transparent);
         QPixmap pixmap(60, 60);
         pixmap.fill(Qt::transparent);
         QPainter painter(&pixmap);
         painter.setPen(Qt::NoPen);
         painter.setBrush(radialGrad);
         painter.drawEllipse(0, 0, 60, 60);
         painter.end();

         m_lightSource = m_scene.addPixmap(pixmap);
         m_lightSource->setZValue(2);

         for (int i = -2; i < 3; ++i)
             for (int j = -2; j < 3; ++j) {
                 QAbstractGraphicsShapeItem *item;
                 if ((i + j) & 1)
                     item = new QGraphicsEllipseItem(0, 0, 50, 50);
                 else
                     item = new QGraphicsRectItem(0, 0, 50, 50);

                 item->setPen(QPen(Qt::black, 1));
                 item->setBrush(QBrush(Qt::white));
                 QGraphicsDropShadowEffect *effect = new QGraphicsDropShadowEffect;
                 effect->setBlurRadius(8);
                 item->setGraphicsEffect(effect);
                 item->setZValue(1);
                 item->setPos(i * 80, j * 80);
                 m_scene.addItem(item);
                 m_items << item;
             }

     }

     void Lighting::animate()
     {
         angle += (M_PI / 30);
         qreal xs = 200 * sin(angle) - 40 + 25;
         qreal ys = 200 * cos(angle) - 40 + 25;
         m_lightSource->setPos(xs, ys);

         for (int i = 0; i < m_items.size(); ++i) {
             QGraphicsItem *item = m_items.at(i);
             Q_ASSERT(item);
             QGraphicsDropShadowEffect *effect = static_cast<QGraphicsDropShadowEffect *>(item->graphicsEffect());
             Q_ASSERT(effect);

             QPointF delta(item->x() - xs, item->y() - ys);
             effect->setOffset(delta.toPoint() / 30);

             qreal dx = delta.x();
             qreal dy = delta.y();
             qreal dd = sqrt(dx * dx + dy * dy);
             QColor color = effect->color();
             color.setAlphaF(qBound(0.4, 1 - dd / 200.0, 0.7));
             effect->setColor(color);
         }

         m_scene.update();
     }

     void Lighting::resizeEvent(QResizeEvent */*event*/)
     {
     #if defined(Q_OS_SYMBIAN) || defined(Q_WS_MAEMO_5) || defined(Q_WS_SIMULATOR)
         fitInView(sceneRect(), Qt::KeepAspectRatio);
     #endif
     }