qtdeclarative/examples/quick/rendercontrol/rendercontrol_rhi/main.cpp

// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

#include <QMainWindow>
#include <QApplication>
#include <QVBoxLayout>
#include <QHBoxLayout>
#include <QMenuBar>
#include <QStatusBar>
#include <QFileDialog>
#include <QMessageBox>
#include <QLabel>
#include <QScrollArea>
#include <QGridLayout>
#include <QPushButton>
#include <QSlider>
#include <QScrollBar>
#include <QListWidget>
#include <QPainter>

#include <QQuickWindow>
#include <QQuickRenderControl>
#include <QQuickRenderTarget>
#include <QQuickGraphicsDevice>
#include <QQuickGraphicsConfiguration>
#include <QQuickItem>
#include <QQmlEngine>
#include <QQmlComponent>

#include <QAnimationDriver>
#include <QElapsedTimer>

#include <rhi/qrhi.h>

//! [anim-driver]
class AnimationDriver : public QAnimationDriver
{
public:
    AnimationDriver() : m_step(16) { }

    void setStep(int milliseconds) { m_step = milliseconds; }

    void advance() override
    {
        m_elapsed += m_step;
        advanceAnimation();
    }

    qint64 elapsed() const override
    {
        return m_elapsed;
    }

private:
    int m_step;
    qint64 m_elapsed = 0;
};
//! [anim-driver]

class ImageLabel;

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(AnimationDriver *animationDriver);
    ~MainWindow();

    void load(const QString &filename);
    void render();

private slots:
    void openRequested();

private:
    void reset();
    void stepAnimations();

    AnimationDriver *m_animationDriver;

    std::unique_ptr<QQuickRenderControl> m_renderControl;
    std::unique_ptr<QQuickWindow> m_scene;
    std::unique_ptr<QQmlEngine> m_qmlEngine;
    std::unique_ptr<QQmlComponent> m_qmlComponent;

    std::unique_ptr<QRhiTexture> m_texture;
    std::unique_ptr<QRhiRenderBuffer> m_ds;
    std::unique_ptr<QRhiTextureRenderTarget> m_rt;
    std::unique_ptr<QRhiRenderPassDescriptor> m_rpDesc;

    qint64 m_frameCount = 0;
    QSize m_thumbnailSize;
    QVector<double> m_cpuTimes;
    QVector<double> m_gpuTimes;

    QLabel *m_apiMsg;
    QLabel *m_statusMsg;
    QLabel *m_avgCpuMsg;
    QLabel *m_avgGpuMsg;
    QLabel *m_driverInfoMsg;

    QScrollArea *m_scrollArea;
    QGridLayout *m_grid;
    QVector<QWidget *> m_gridWidgets;

public:
#if QT_CONFIG(vulkan)
    QVulkanInstance *m_vulkanInstance = nullptr;
#endif

    ImageLabel *m_focus = nullptr;
    QLabel *m_fullSizeViewerWindow = nullptr;
    QVector<QImage> m_frames;
};

MainWindow::MainWindow(AnimationDriver *animationDriver)
    : m_animationDriver(animationDriver)
{
    QWidget *centralWidget = new QWidget(this);
    QVBoxLayout *vlayout = new QVBoxLayout(centralWidget);
    QHBoxLayout *controlLayout = new QHBoxLayout;
    vlayout->addLayout(controlLayout);

    QPushButton *btn = new QPushButton(tr("Next frame"));
    QObject::connect(btn, &QPushButton::clicked, btn, [this] {
        render();
    });
    controlLayout->addWidget(btn);

    QPushButton *btnMulti = new QPushButton(tr("Next 10 frames"));
    QObject::connect(btnMulti, &QPushButton::clicked, btn, [this] {
        for (int i = 0; i < 10; ++i)
            QMetaObject::invokeMethod(this, &MainWindow::render, Qt::QueuedConnection);
    });
    controlLayout->addWidget(btnMulti);

//! [anim-slider]
    QSlider *animSlider = new QSlider;
    animSlider->setOrientation(Qt::Horizontal);
    animSlider->setMinimum(1);
    animSlider->setMaximum(1000);
    QLabel *animLabel = new QLabel;
    QObject::connect(animSlider, &QSlider::valueChanged, animSlider, [this, animLabel, animSlider] {
        m_animationDriver->setStep(animSlider->value());
        animLabel->setText(tr("Simulated elapsed time per frame: %1 ms").arg(animSlider->value()));
    });
    animSlider->setValue(16);
//! [anim-slider]
    controlLayout->addWidget(animLabel);
    controlLayout->addWidget(animSlider);

    QGridLayout *gridLayout = new QGridLayout;
    vlayout->addLayout(gridLayout);

    QWidget *viewport = new QWidget;
    m_grid = new QGridLayout(viewport);
    m_scrollArea = new QScrollArea;
    m_scrollArea->setWidgetResizable(true);
    m_scrollArea->setWidget(viewport);
    QObject::connect(m_scrollArea->verticalScrollBar(), &QScrollBar::rangeChanged, this, [this] {
        m_scrollArea->verticalScrollBar()->setSliderPosition(m_scrollArea->verticalScrollBar()->maximum());
    });

    gridLayout->addWidget(m_scrollArea);
    setCentralWidget(centralWidget);

    QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
    fileMenu->addAction(tr("&Open"), this, &MainWindow::openRequested);
    fileMenu->addAction(tr("E&xit"), qApp, &QCoreApplication::quit);

    m_statusMsg = new QLabel;
    statusBar()->addWidget(m_statusMsg);
    m_avgCpuMsg = new QLabel;
    statusBar()->addWidget(m_avgCpuMsg);
    m_avgGpuMsg = new QLabel;
    statusBar()->addWidget(m_avgGpuMsg);
    m_apiMsg = new QLabel;
    statusBar()->addWidget(m_apiMsg);
    m_driverInfoMsg = new QLabel;
    statusBar()->addWidget(m_driverInfoMsg);
}

MainWindow::~MainWindow()
{
    delete m_fullSizeViewerWindow;
}

void MainWindow::openRequested()
{
    QString filename = QFileDialog::getOpenFileName(this, tr("Open file"), QString(), tr("QML files (*.qml);;All files (*.*)"));
    if (!filename.isEmpty())
        load(filename);
}

void MainWindow::reset()
{
    m_rpDesc.reset();
    m_rt.reset();
    m_ds.reset();
    m_texture.reset();

    m_qmlComponent.reset();
    m_qmlEngine.reset();
    m_scene.reset();
    m_renderControl.reset();

    m_apiMsg->setText(QString());
    m_statusMsg->setText(QString());
    m_avgCpuMsg->setText(QString());
    m_avgGpuMsg->setText(QString());
    m_driverInfoMsg->setText(QString());

    m_frameCount = 0;

    qDeleteAll(m_gridWidgets);
    m_gridWidgets.clear();

    delete m_fullSizeViewerWindow;
    m_fullSizeViewerWindow = nullptr;
    m_focus = nullptr;
}

//! [load-1]
void MainWindow::load(const QString &filename)
{
    reset();

    m_renderControl.reset(new QQuickRenderControl);
    m_scene.reset(new QQuickWindow(m_renderControl.get()));

    // enable lastCompletedGpuTime() on QRhiCommandBuffer, if supported by the underlying 3D API
    QQuickGraphicsConfiguration config;
    config.setTimestamps(true);
    m_scene->setGraphicsConfiguration(config);

#if QT_CONFIG(vulkan)
    if (m_scene->graphicsApi() == QSGRendererInterface::Vulkan)
        m_scene->setVulkanInstance(m_vulkanInstance);
#endif

    m_qmlEngine.reset(new QQmlEngine);
    m_qmlComponent.reset(new QQmlComponent(m_qmlEngine.get(), QUrl::fromLocalFile(filename)));
    if (m_qmlComponent->isError()) {
        for (const QQmlError &error : m_qmlComponent->errors())
            qWarning() << error.url() << error.line() << error;
        QMessageBox::critical(this, tr("Cannot load QML scene"), tr("Failed to load %1").arg(filename));
        reset();
        return;
    }
//! [load-1]

//! [load-instantiate]
    QObject *rootObject = m_qmlComponent->create();
    if (m_qmlComponent->isError()) {
        for (const QQmlError &error : m_qmlComponent->errors())
            qWarning() << error.url() << error.line() << error;
        QMessageBox::critical(this, tr("Cannot load QML scene"), tr("Failed to create component"));
        reset();
        return;
    }

    QQuickItem *rootItem = qobject_cast<QQuickItem *>(rootObject);
    if (!rootItem) {
        // Get rid of the on-screen window, if the root object was a Window
        if (QQuickWindow *w = qobject_cast<QQuickWindow *>(rootObject))
            delete w;
        QMessageBox::critical(this,
                              tr("Invalid root item in QML scene"),
                              tr("Root object is not a QQuickItem. If this is a scene with Window in it, note that such scenes are not supported."));
        reset();
        return;
    }

    if (rootItem->size().width() < 16)
        rootItem->setSize(QSizeF(640, 360));

    m_scene->contentItem()->setSize(rootItem->size());
    m_scene->setGeometry(0, 0, rootItem->width(), rootItem->height());

    rootItem->setParentItem(m_scene->contentItem());

    m_statusMsg->setText(tr("QML scene loaded"));
//! [load-instantiate]

//! [load-graphicsinit]
    const bool initSuccess = m_renderControl->initialize();
    if (!initSuccess) {
        QMessageBox::critical(this, tr("Cannot initialize renderer"), tr("QQuickRenderControl::initialize() failed"));
        reset();
        return;
    }

    const QSGRendererInterface::GraphicsApi api = m_scene->rendererInterface()->graphicsApi();
    switch (api) {
    case QSGRendererInterface::OpenGL:
        m_apiMsg->setText(tr("OpenGL"));
        break;
    case QSGRendererInterface::Direct3D11:
        m_apiMsg->setText(tr("D3D11"));
        break;
    case QSGRendererInterface::Direct3D12:
        m_apiMsg->setText(tr("D3D12"));
        break;
    case QSGRendererInterface::Vulkan:
        m_apiMsg->setText(tr("Vulkan"));
        break;
    case QSGRendererInterface::Metal:
        m_apiMsg->setText(tr("Metal"));
        break;
    default:
        m_apiMsg->setText(tr("Unknown 3D API"));
        break;
    }

    QRhi *rhi = m_renderControl->rhi();
    if (!rhi) {
        QMessageBox::critical(this, tr("Cannot render"), tr("No QRhi from QQuickRenderControl"));
        reset();
        return;
    }

    m_driverInfoMsg->setText(QString::fromUtf8(rhi->driverInfo().deviceName));
//! [load-graphicsinit]

//! [texture-setup]
    const QSize pixelSize = rootItem->size().toSize(); // no scaling, i.e. the item size is in pixels

    m_texture.reset(rhi->newTexture(QRhiTexture::RGBA8, pixelSize, 1,
                                    QRhiTexture::RenderTarget | QRhiTexture::UsedAsTransferSource));
    if (!m_texture->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create texture object"));
        reset();
        return;
    }

    m_ds.reset(rhi->newRenderBuffer(QRhiRenderBuffer::DepthStencil, pixelSize, 1));
    if (!m_ds->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create depth-stencil buffer"));
        reset();
        return;
    }

    QRhiTextureRenderTargetDescription rtDesc(QRhiColorAttachment(m_texture.get()));
    rtDesc.setDepthStencilBuffer(m_ds.get());
    m_rt.reset(rhi->newTextureRenderTarget(rtDesc));
    m_rpDesc.reset(m_rt->newCompatibleRenderPassDescriptor());
    m_rt->setRenderPassDescriptor(m_rpDesc.get());
    if (!m_rt->create()) {
        QMessageBox::critical(this, tr("Cannot render"), tr("Cannot create render target"));
        reset();
        return;
    }

    m_scene->setRenderTarget(QQuickRenderTarget::fromRhiRenderTarget(m_rt.get()));
//! [texture-setup]

    render();
}

class ImageLabel : public QLabel
{
public:
    ImageLabel(MainWindow *mw, int frameIndex)
        : m_mainWindow(mw),
          m_frameIndex(frameIndex)
    {
    }

    void mousePressEvent(QMouseEvent *) override {
        if (m_mainWindow->m_focus != this) {
            ImageLabel *oldFocus = m_mainWindow->m_focus;
            m_mainWindow->m_focus = this;
            if (oldFocus)
                oldFocus->update();
            update();
        }
    }

    void paintEvent(QPaintEvent *e) override {

        if (m_mainWindow->m_focus == this) {
            QPainter p(this);
            p.fillRect(0, 0, width(), height(), Qt::blue);
            p.end();
            QLabel::paintEvent(e);
            p.begin(this);
            p.setOpacity(0.5);
            p.fillRect(0, 0, width(), height(), Qt::blue);
        } else {
            QLabel::paintEvent(e);
        }
    }

    void mouseDoubleClickEvent(QMouseEvent *) override {
        QLabel *&w(m_mainWindow->m_fullSizeViewerWindow);
        if (!w)
            w = new QLabel;
        const QImage &image(m_mainWindow->m_frames[m_frameIndex]);
        w->resize(image.width(), image.height());
        w->setPixmap(QPixmap::fromImage(image));
        w->show();
        w->activateWindow();
    }

    MainWindow *m_mainWindow;
    int m_frameIndex;
};

void MainWindow::render()
{
    if (!m_renderControl)
        return;

    if (m_frameCount > 0)
        stepAnimations();

//! [render-core]
    QElapsedTimer cpuTimer;
    cpuTimer.start();

    m_renderControl->polishItems();

    m_renderControl->beginFrame();

    m_renderControl->sync();
    m_renderControl->render();

    QRhi *rhi = m_renderControl->rhi();
    QRhiReadbackResult readResult;
    QRhiResourceUpdateBatch *readbackBatch = rhi->nextResourceUpdateBatch();
    readbackBatch->readBackTexture(m_texture.get(), &readResult);
    m_renderControl->commandBuffer()->resourceUpdate(readbackBatch);

    m_renderControl->endFrame();

    const double gpuRenderTimeMs = m_renderControl->commandBuffer()->lastCompletedGpuTime() * 1000.0;
    const double cpuRenderTimeMs = cpuTimer.nsecsElapsed() / 1000000.0;

    // m_renderControl->begin/endFrame() is based on QRhi's
    // begin/endOffscreenFrame() under the hood, meaning it does not do
    // pipelining, unlike swapchain-based frames, and therefore the readback is
    // guaranteed to complete once endFrame() returns.
    QImage wrapperImage(reinterpret_cast<const uchar *>(readResult.data.constData()),
                    readResult.pixelSize.width(), readResult.pixelSize.height(),
                    QImage::Format_RGBA8888_Premultiplied);
    QImage result;
if (rhi->isYUpInFramebuffer())
    result = wrapperImage.mirrored();
else
    result = wrapperImage.copy();

//! [render-core]

    m_gpuTimes.append(gpuRenderTimeMs);
    m_cpuTimes.append(cpuRenderTimeMs);

    m_frames.append(result);

    if (m_thumbnailSize.isEmpty())
        m_thumbnailSize = size() / 4;

    const QImage thumbnail = result.scaled(m_thumbnailSize, Qt::KeepAspectRatio);

    ImageLabel *image = new ImageLabel(this, m_frames.count() - 1);
    image->setPixmap(QPixmap::fromImage(thumbnail));
    image->setAlignment(Qt::AlignCenter);

    QLabel *label = new QLabel(tr("Frame %1\nCPU: %2 ms GPU: %3 ms").arg(m_frameCount).arg(cpuRenderTimeMs, 0, 'f', 4).arg(gpuRenderTimeMs, 0, 'f', 4));
    label->setAlignment(Qt::AlignCenter);
    QWidget *container = new QWidget;
    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(image);
    layout->addWidget(label);
    container->setLayout(layout);
    m_grid->addWidget(container, m_frameCount / 3, m_frameCount % 3);
    m_gridWidgets.append(container);

    m_scrollArea->verticalScrollBar()->setSliderPosition(m_scrollArea->verticalScrollBar()->maximum());

    m_frameCount += 1;

    double v = 0;
    for (double t : m_cpuTimes)
        v += t;
    v /= m_cpuTimes.count();
    m_avgCpuMsg->setText(tr("Avg. CPU render time: %1 ms").arg(v, 0, 'f', 4));
    if (m_cpuTimes.count() > 64) {
        m_cpuTimes.clear();
        m_cpuTimes.append(v);
    }
    v = 0;
    for (double t : m_gpuTimes)
        v += t;
    v /= m_gpuTimes.count();
    m_avgGpuMsg->setText(tr("Avg. GPU render time: %1 ms").arg(v, 0, 'f', 4));
    if (m_gpuTimes.count() > 64) {
        m_gpuTimes.clear();
        m_gpuTimes.append(v);
    }
}

//! [anim-step]
void MainWindow::stepAnimations()
{
    // Now the Qt Quick scene will think that <slider value> milliseconds have
    // elapsed and update animations accordingly when doing the next frame.
    m_animationDriver->advance();
}
//! [anim-step]

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

    AnimationDriver animDriver;
    animDriver.install();

#if QT_CONFIG(vulkan)
    QVulkanInstance vulkanInstance;
#endif

    MainWindow mainWindow(&animDriver);

//! [apiselect]
    QDialog apiSelect;
    QVBoxLayout *selLayout = new QVBoxLayout;
    selLayout->addWidget(new QLabel(QObject::tr("Select graphics API to use")));
    QListWidget *apiList = new QListWidget;
    QVarLengthArray<QSGRendererInterface::GraphicsApi, 5> apiValues;
#ifdef Q_OS_WIN
    apiList->addItem("Direct3D 11");
    apiValues.append(QSGRendererInterface::Direct3D11);
    apiList->addItem("Direct3D 12");
    apiValues.append(QSGRendererInterface::Direct3D12);
#endif
#if defined(Q_OS_MACOS) || defined(Q_OS_IOS)
    apiList->addItem("Metal");
    apiValues.append(QSGRendererInterface::Metal);
#endif
#if QT_CONFIG(vulkan)
    apiList->addItem("Vulkan");
    apiValues.append(QSGRendererInterface::Vulkan);
#endif
#if QT_CONFIG(opengl)
    apiList->addItem("OpenGL / OpenGL ES");
    apiValues.append(QSGRendererInterface::OpenGL);
#endif
    if (apiValues.isEmpty()) {
        QMessageBox::critical(nullptr, QObject::tr("No 3D graphics API"), QObject::tr("No 3D graphics APIs are supported in this Qt build"));
        return 1;
    }
//! [apiselect]
    apiList->setCurrentRow(0);
    selLayout->addWidget(apiList);
    QPushButton *okBtn = new QPushButton("Ok");
    okBtn->setDefault(true);
    selLayout->addWidget(okBtn);
    apiSelect.setLayout(selLayout);
    apiSelect.resize(320, 200);
    apiSelect.show();

    QObject::connect(okBtn, &QPushButton::clicked, okBtn, [apiList, &apiSelect, &apiValues, &mainWindow
#if QT_CONFIG(vulkan)
                                                           , &vulkanInstance
#endif
    ] {
        const QSGRendererInterface::GraphicsApi api = apiValues[apiList->currentRow()];
        QQuickWindow::setGraphicsApi(api);

#if QT_CONFIG(vulkan)
        if (api == QSGRendererInterface::Vulkan) {
            vulkanInstance.setExtensions(QQuickGraphicsConfiguration::preferredInstanceExtensions());
            if (!vulkanInstance.create()) {
                QMessageBox::critical(nullptr, QObject::tr("Cannot initialize Vulkan"), QObject::tr("Failed to create VkInstance"));
                return;
            }
            mainWindow.m_vulkanInstance = &vulkanInstance;
        }
#endif

        mainWindow.resize(1280, 720);
        mainWindow.show();
        mainWindow.load(QLatin1String(":/demo.qml"));
        // load() renders one frame, add 19 more
        for (int i = 1; i <= 19; ++i) {
            mainWindow.render();
            // have to process events, e.g. to get queued metacalls delivered
            QCoreApplication::processEvents();
        }

        apiSelect.close();
    });

    return app.exec();
}

#include "main.moc"