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# svgview.cpp Example File
painting/svgviewer/svgview.cpp

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     ** 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
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     ** packaging of this file.  Please review the following information to
     ** ensure the GNU Lesser General Public License version 2.1 requirements
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     ** 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
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     #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);
         setViewportUpdateMode(FullViewportUpdate);

         // 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();
     }