- Qt 5.5
- Qt Quick
- Qt Quick Widgets Example
- main.cpp Example File
- Qt 5.5.1 Reference Documentation

# main.cpp Example File

quickwidgets/quickwidget/main.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    #include <QQuickWidget>
    #include <QQmlError>
    #include <QtWidgets>

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

    private slots:
        void quickWidgetStatusChanged(QQuickWidget::Status);
        void sceneGraphError(QQuickWindow::SceneGraphError error, const QString &message);
        void grabToFile();
        void renderToFile();

    private:
        QQuickWidget *m_quickWidget;
    };

    MainWindow::MainWindow()
       : m_quickWidget(new QQuickWidget)
    {
        QSurfaceFormat format;
        if (QCoreApplication::arguments().contains(QStringLiteral("--coreprofile"))) {
            format.setVersion(4, 4);
            format.setProfile(QSurfaceFormat::CoreProfile);
        }
        if (QCoreApplication::arguments().contains(QStringLiteral("--multisample")))
            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, SIGNAL(statusChanged(QQuickWidget::Status)),
                this, SLOT(quickWidgetStatusChanged(QQuickWidget::Status)));
        connect(m_quickWidget, SIGNAL(sceneGraphError(QQuickWindow::SceneGraphError,QString)),
                this, SLOT(sceneGraphError(QQuickWindow::SceneGraphError,QString)));
        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"));
        QAction *grabAction = fileMenu->addAction(tr("Grab to image"));
        connect(grabAction, SIGNAL(triggered()), this, SLOT(grabToFile()));
        QAction *renderAction = fileMenu->addAction(tr("Render to pixmap"));
        connect(renderAction, SIGNAL(triggered()), this, SLOT(renderToFile()));
        QAction *quitAction = fileMenu->addAction(tr("Quit"));
        connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
    }

    void MainWindow::quickWidgetStatusChanged(QQuickWidget::Status status)
    {
        if (status == QQuickWidget::Error) {
            QStringList errors;
            foreach (const QQmlError &error, m_quickWidget->errors())
                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)
    {
        QString t;
        QFileDialog fd(parent, t, QString());
        fd.setAcceptMode(QFileDialog::AcceptSave);
        fd.setDefaultSuffix("png");
        fd.selectFile("test.png");
        if (fd.exec() == QDialog::Accepted)
            saveable->save(fd.selectedFiles().first());
    }

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

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

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

        MainWindow mainWindow;
        mainWindow.show();

        return app.exec();
    }

    #include "main.moc"