Qt 5.11 | Qt Quick | Qt Quick Widgets Example | main.cpp Example File

Qt 5.11.3 Reference Documentation

# main.cpp Example File

quickwidgets/quickwidget/main.cpp

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      #include <QQuickWidget>
      #include <QQuickItem>
      #include <QQmlError>
      #include <QtWidgets>
      #include "fbitem.h"

      static bool optMultipleSample = false;
      static bool optCoreProfile = false;

      class MainWindow : public QMainWindow {
          Q_OBJECT
      public:
          MainWindow();

      private slots:
          void quickWidgetStatusChanged(QQuickWidget::Status);
          void sceneGraphError(QQuickWindow::SceneGraphError error, const QString &message);
          void grabFramebuffer();
          void renderToPixmap();
          void grabToImage();
          void createQuickWidgetsInTabs(QMdiArea *mdiArea);

      private:
          QQuickWidget *m_quickWidget;
      };

      MainWindow::MainWindow()
         : m_quickWidget(new QQuickWidget)
      {
          QSurfaceFormat format;
          if (optCoreProfile) {
              format.setVersion(4, 4);
              format.setProfile(QSurfaceFormat::CoreProfile);
          }
          if (optMultipleSample)
              format.setSamples(4);
          m_quickWidget->setFormat(format);

          QMdiArea *centralWidget = new QMdiArea;

          QLCDNumber *lcd = new QLCDNumber;
          lcd->display(1337);
          lcd->setMinimumSize(250,100);
          centralWidget->addSubWindow(lcd);

          QUrl source("qrc:quickwidget/rotatingsquare.qml");

          connect(m_quickWidget, &QQuickWidget::statusChanged,
                  this, &MainWindow::quickWidgetStatusChanged);
          connect(m_quickWidget, &QQuickWidget::sceneGraphError,
                  this, &MainWindow::sceneGraphError);
          m_quickWidget->resize(300,300);
          m_quickWidget->setResizeMode(QQuickWidget::SizeRootObjectToView );
          m_quickWidget->setSource(source);

          centralWidget->addSubWindow(m_quickWidget);

          setCentralWidget(centralWidget);

          QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
          fileMenu->addAction(tr("Grab framebuffer"), this, &MainWindow::grabFramebuffer);
          fileMenu->addAction(tr("Render to pixmap"), this, &MainWindow::renderToPixmap);
          fileMenu->addAction(tr("Grab via grabToImage"), this, &MainWindow::grabToImage);
          fileMenu->addAction(tr("Quit"), qApp, &QCoreApplication::quit);

          QMenu *windowMenu = menuBar()->addMenu(tr("&Window"));
          windowMenu->addAction(tr("Add tab widget"), this,
                                [this, centralWidget] { createQuickWidgetsInTabs(centralWidget); });
      }

      void MainWindow::createQuickWidgetsInTabs(QMdiArea *mdiArea)
      {
          QTabWidget *tabWidget = new QTabWidget;

          const QSize size(400, 400);

          QQuickWidget *w = new QQuickWidget;
          w->resize(size);
          w->setResizeMode(QQuickWidget::SizeRootObjectToView);
          w->setSource(QUrl("qrc:quickwidget/rotatingsquaretab.qml"));

          tabWidget->addTab(w, tr("Plain Quick content"));

          w = new QQuickWidget;
          w->resize(size);
          w->setResizeMode(QQuickWidget::SizeRootObjectToView);
          w->setSource(QUrl("qrc:quickwidget/customgl.qml"));

          tabWidget->addTab(w, tr("Custom OpenGL drawing"));

          mdiArea->addSubWindow(tabWidget);
          tabWidget->show();
      }

      void MainWindow::quickWidgetStatusChanged(QQuickWidget::Status status)
      {
          if (status == QQuickWidget::Error) {
              QStringList errors;
              const auto widgetErrors = m_quickWidget->errors();
              for (const QQmlError &error : widgetErrors)
                  errors.append(error.toString());
              statusBar()->showMessage(errors.join(QStringLiteral(", ")));
          }
      }

      void MainWindow::sceneGraphError(QQuickWindow::SceneGraphError, const QString &message)
      {
           statusBar()->showMessage(message);
      }

      template<class T> void saveToFile(QWidget *parent, T *saveable)
      {
          QFileDialog fd(parent);
          fd.setAcceptMode(QFileDialog::AcceptSave);
          fd.setDefaultSuffix("png");
          fd.selectFile("test.png");
          if (fd.exec() == QDialog::Accepted)
              saveable->save(fd.selectedFiles().first());
      }

      void MainWindow::grabFramebuffer()
      {
          QImage image = m_quickWidget->grabFramebuffer();
          saveToFile(this, &image);
      }

      void MainWindow::renderToPixmap()
      {
          QPixmap pixmap(m_quickWidget->size());
          m_quickWidget->render(&pixmap);
          saveToFile(this, &pixmap);
      }

      void MainWindow::grabToImage()
      {
          QFileDialog fd(this);
          fd.setAcceptMode(QFileDialog::AcceptSave);
          fd.setDefaultSuffix("png");
          fd.selectFile("test_grabToImage.png");
          if (fd.exec() == QDialog::Accepted) {
              QMetaObject::invokeMethod(m_quickWidget->rootObject(), "performLayerBasedGrab",
                                        Q_ARG(QVariant, fd.selectedFiles().first()));
          }
      }

      int main(int argc, char **argv)
      {
          QApplication app(argc, argv);

          QCoreApplication::setApplicationName("Qt QQuickWidget Example");
          QCoreApplication::setOrganizationName("QtProject");
          QCoreApplication::setApplicationVersion(QT_VERSION_STR);
          QCommandLineParser parser;
          parser.setApplicationDescription(QCoreApplication::applicationName());
          parser.addHelpOption();
          parser.addVersionOption();
          QCommandLineOption multipleSampleOption("multisample", "Multisampling");
          parser.addOption(multipleSampleOption);
          QCommandLineOption coreProfileOption("coreprofile", "Use core profile");
          parser.addOption(coreProfileOption);

          parser.process(app);

          optMultipleSample = parser.isSet(multipleSampleOption);
          optCoreProfile = parser.isSet(coreProfileOption);

          qmlRegisterType<FbItem>("QuickWidgetExample", 1, 0, "FbItem");

          MainWindow mainWindow;
          mainWindow.show();

          return app.exec();
      }

      #include "main.moc"