mainwindow.cpp Example File

svgviewer/mainwindow.cpp 
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 #include "mainwindow.h"
 #include "exportdialog.h"

 #include <QtWidgets>
 #include <QSvgRenderer>

 #include "svgview.h"

 static inline QString picturesLocation()
 {
     return QStandardPaths::standardLocations(QStandardPaths::PicturesLocation).value(0, QDir::currentPath());
 }

 MainWindow::MainWindow()
     : QMainWindow()
     , m_view(new SvgView)
     , m_zoomLabel(new QLabel)
 {
     QToolBar *toolBar = new QToolBar(this);
     addToolBar(Qt::TopToolBarArea, toolBar);

     QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
     const QIcon openIcon = QIcon::fromTheme("document-open", QIcon(":/qt-project.org/styles/commonstyle/images/standardbutton-open-32.png"));
     QAction *openAction = fileMenu->addAction(openIcon, tr("&Open..."), this, &MainWindow::openFile);
     openAction->setShortcut(QKeySequence::Open);
     toolBar->addAction(openAction);
     const QIcon exportIcon = QIcon::fromTheme("document-save", QIcon(":/qt-project.org/styles/commonstyle/images/standardbutton-save-32.png"));
     QAction *exportAction = fileMenu->addAction(exportIcon, tr("&Export..."), this, &MainWindow::exportImage);
     exportAction->setToolTip(tr("Export Image"));
     exportAction->setShortcut(Qt::CTRL + Qt::Key_E);
     toolBar->addAction(exportAction);
     QAction *quitAction = fileMenu->addAction(tr("E&xit"), qApp, QCoreApplication::quit);
     quitAction->setShortcuts(QKeySequence::Quit);

     QMenu *viewMenu = menuBar()->addMenu(tr("&View"));
     m_backgroundAction = viewMenu->addAction(tr("&Background"));
     m_backgroundAction->setEnabled(false);
     m_backgroundAction->setCheckable(true);
     m_backgroundAction->setChecked(false);
     connect(m_backgroundAction, &QAction::toggled, m_view, &SvgView::setViewBackground);

     m_outlineAction = viewMenu->addAction(tr("&Outline"));
     m_outlineAction->setEnabled(false);
     m_outlineAction->setCheckable(true);
     m_outlineAction->setChecked(true);
     connect(m_outlineAction, &QAction::toggled, m_view, &SvgView::setViewOutline);

     viewMenu->addSeparator();
     QAction *zoomAction = viewMenu->addAction(tr("Zoom &In"), m_view, &SvgView::zoomIn);
     zoomAction->setShortcut(QKeySequence::ZoomIn);
     zoomAction = viewMenu->addAction(tr("Zoom &Out"), m_view, &SvgView::zoomOut);
     zoomAction->setShortcut(QKeySequence::ZoomOut);
     zoomAction = viewMenu->addAction(tr("Reset Zoom"), m_view, &SvgView::resetZoom);
     zoomAction->setShortcut(Qt::CTRL + Qt::Key_0);

     QMenu *rendererMenu = menuBar()->addMenu(tr("&Renderer"));
     m_nativeAction = rendererMenu->addAction(tr("&Native"));
     m_nativeAction->setCheckable(true);
     m_nativeAction->setChecked(true);
     m_nativeAction->setData(int(SvgView::Native));
 #ifndef QT_NO_OPENGL
     m_glAction = rendererMenu->addAction(tr("&OpenGL"));
     m_glAction->setCheckable(true);
     m_glAction->setData(int(SvgView::OpenGL));
 #endif
     m_imageAction = rendererMenu->addAction(tr("&Image"));
     m_imageAction->setCheckable(true);
     m_imageAction->setData(int(SvgView::Image));

     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, &QAction::toggled, m_view, &SvgView::setHighQualityAntialiasing);
 #ifdef QT_NO_OPENGL
     m_highQualityAntialiasingAction->setVisible(false);
 #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(rendererGroup, &QActionGroup::triggered,
             [this] (QAction *a) { setRenderer(a->data().toInt()); });

     QMenu *help = menuBar()->addMenu(tr("&Help"));
     help->addAction(tr("About Qt"), qApp, &QApplication::aboutQt);

     setCentralWidget(m_view);

     m_zoomLabel->setToolTip(tr("Use the mouse wheel to zoom"));
     statusBar()->addPermanentWidget(m_zoomLabel);
     updateZoomLabel();
     connect(m_view, &SvgView::zoomChanged, this, &MainWindow::updateZoomLabel);
 }

 void MainWindow::openFile()
 {
     QFileDialog fileDialog(this);
     fileDialog.setAcceptMode(QFileDialog::AcceptOpen);
     fileDialog.setMimeTypeFilters(QStringList() << "image/svg+xml" << "image/svg+xml-compressed");
     fileDialog.setWindowTitle(tr("Open SVG File"));
     if (m_currentPath.isEmpty())
         fileDialog.setDirectory(picturesLocation());

     while (fileDialog.exec() == QDialog::Accepted && !loadFile(fileDialog.selectedFiles().constFirst()))
         ;
 }

 bool MainWindow::loadFile(const QString &fileName)
 {
     if (!QFileInfo::exists(fileName) || !m_view->openFile(fileName)) {
         QMessageBox::critical(this, tr("Open SVG File"),
                               tr("Could not open file '%1'.").arg(QDir::toNativeSeparators(fileName)));
         return false;
     }

     if (!fileName.startsWith(":/")) {
         m_currentPath = fileName;
         setWindowFilePath(fileName);
         const QSize size = m_view->svgSize();
         const QString message =
             tr("Opened %1, %2x%3").arg(QFileInfo(fileName).fileName()).arg(size.width()).arg(size.width());
         statusBar()->showMessage(message);
     }

     m_outlineAction->setEnabled(true);
     m_backgroundAction->setEnabled(true);

     const QSize availableSize = QApplication::desktop()->availableGeometry(this).size();
     resize(m_view->sizeHint().expandedTo(availableSize / 4) + QSize(80, 80 + menuBar()->height()));

     return true;
 }

 void MainWindow::setRenderer(int renderMode)
 {

     m_highQualityAntialiasingAction->setEnabled(renderMode == SvgView::OpenGL);
     m_view->setRenderer(static_cast<SvgView::RendererType>(renderMode));
 }

 void MainWindow::exportImage()
 {
     ExportDialog exportDialog(this);
     exportDialog.setExportSize(m_view->svgSize());
     QString fileName;
     if (m_currentPath.isEmpty()) {
         fileName = picturesLocation() + QLatin1String("/export.png");
     } else {
         const QFileInfo fi(m_currentPath);
         fileName = fi.absolutePath() + QLatin1Char('/') + fi.baseName() + QLatin1String(".png");
     }
     exportDialog.setExportFileName(fileName);

     while (true) {
         if (exportDialog.exec() != QDialog::Accepted)
             break;

         const QSize imageSize = exportDialog.exportSize();
         QImage image(imageSize, QImage::Format_ARGB32);
         image.fill(Qt::transparent);
         QPainter painter;
         painter.begin(&image);
         m_view->renderer()->render(&painter, QRectF(QPointF(), QSizeF(imageSize)));
         painter.end();

         const QString fileName = exportDialog.exportFileName();
         if (image.save(fileName)) {

             const QString message = tr("Exported %1, %2x%3, %4 bytes")
                 .arg(QDir::toNativeSeparators(fileName)).arg(imageSize.width()).arg(imageSize.height())
                 .arg(QFileInfo(fileName).size());
             statusBar()->showMessage(message);
             break;
         } else {
             QMessageBox::critical(this, tr("Export Image"),
                                   tr("Could not write file '%1'.").arg(QDir::toNativeSeparators(fileName)));
         }
     }
 }

 void MainWindow::updateZoomLabel()
 {
     const int percent = qRound(m_view->zoomFactor() * qreal(100));
     m_zoomLabel->setText(QString::number(percent) + QLatin1Char('%'));
 }

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