main.cpp Example File

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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"