Qt 5.9 | Qt SVG | SVG Viewer Example | svgview.cpp Example File

Qt 5.9.2 Reference Documentation

# svgview.cpp Example File

svgviewer/svgview.cpp

      /****************************************************************************
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      ** This file is part of the examples of the Qt Toolkit.
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      ** $QT_BEGIN_LICENSE:BSD$
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      #include "svgview.h"

      #include <QSvgRenderer>

      #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(nullptr)
          , m_backgroundItem(nullptr)
          , m_outlineItem(nullptr)
      {
          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();
      }

      QSize SvgView::svgSize() const
      {
          return m_svgItem ? m_svgItem->boundingRect().size().toSize() : QSize();
      }

      bool SvgView::openFile(const QString &fileName)
      {
          QGraphicsScene *s = scene();

          const bool drawBackground = (m_backgroundItem ? m_backgroundItem->isVisible() : false);
          const bool drawOutline = (m_outlineItem ? m_outlineItem->isVisible() : true);

          QScopedPointer<QGraphicsSvgItem> svgItem(new QGraphicsSvgItem(fileName));
          if (!svgItem->renderer()->isValid())
              return false;

          s->clear();
          resetTransform();

          m_svgItem = svgItem.take();
          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));
          return true;
      }

      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();
      }

      QSvgRenderer *SvgView::renderer() const
      {
          if (m_svgItem)
              return m_svgItem->renderer();
          return nullptr;
      }