multiwindow_threaded.cpp 20.5 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58
/****************************************************************************
**
** Copyright (C) 2018 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of The Qt Company Ltd nor the names of its
**     contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QApplication>
#include <QWidget>
#include <QLabel>
#include <QPlainTextEdit>
#include <QPushButton>
#include <QVBoxLayout>

#include <QThread>
59
#include <QMutex>
60
#include <QWaitCondition>
61 62
#include <QQueue>
#include <QEvent>
63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120
#include <QCommandLineParser>
#include <QWindow>
#include <QPlatformSurfaceEvent>
#include <QElapsedTimer>

#include <QBakedShader>
#include <QFile>

#ifndef QT_NO_OPENGL
#include <QRhiGles2InitParams>
#include <QOpenGLContext>
#include <QOffscreenSurface>
#endif

#if QT_CONFIG(vulkan)
#include <QLoggingCategory>
#include <QRhiVulkanInitParams>
#endif

#ifdef Q_OS_WIN
#include <QRhiD3D11InitParams>
#endif

#ifdef Q_OS_DARWIN
#include <QRhiMetalInitParams>
#endif

enum GraphicsApi
{
    OpenGL,
    Vulkan,
    D3D11,
    Metal
};

static GraphicsApi graphicsApi;

static QString graphicsApiName()
{
    switch (graphicsApi) {
    case OpenGL:
        return QLatin1String("OpenGL 2.x");
    case Vulkan:
        return QLatin1String("Vulkan");
    case D3D11:
        return QLatin1String("Direct3D 11");
    case Metal:
        return QLatin1String("Metal");
    default:
        break;
    }
    return QString();
}

#if QT_CONFIG(vulkan)
QVulkanInstance *instance = nullptr;
#endif

121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165
// Window (main thread) emit signals -> Renderer::send* (main thread) -> event queue (add on main, process on render thread) -> Renderer::renderEvent (render thread)

// event queue is taken from the Qt Quick scenegraph as-is
// all this below is conceptually the same as the QSG threaded render loop
class RenderThreadEventQueue : public QQueue<QEvent *>
{
public:
    RenderThreadEventQueue()
        : waiting(false)
    {
    }

    void addEvent(QEvent *e) {
        mutex.lock();
        enqueue(e);
        if (waiting)
            condition.wakeOne();
        mutex.unlock();
    }

    QEvent *takeEvent(bool wait) {
        mutex.lock();
        if (isEmpty() && wait) {
            waiting = true;
            condition.wait(&mutex);
            waiting = false;
        }
        QEvent *e = dequeue();
        mutex.unlock();
        return e;
    }

    bool hasMoreEvents() {
        mutex.lock();
        bool has = !isEmpty();
        mutex.unlock();
        return has;
    }

private:
    QMutex mutex;
    QWaitCondition condition;
    bool waiting;
};

166 167 168 169 170 171 172 173 174 175 176 177 178 179
struct Renderer;

struct Thread : public QThread
{
    Thread(Renderer *renderer_)
        : renderer(renderer_)
    {
        active = true;
        start();
    }
    void run() override;

    Renderer *renderer;
    bool active;
180 181 182 183 184 185
    RenderThreadEventQueue eventQueue;
    bool sleeping = false;
    bool stopEventProcessing = false;
    bool pendingRender = false;
    bool pendingRenderIsNewExpose = false;
    // mutex and cond used to allow the main thread waiting until something completes on the render thread
186 187 188 189
    QMutex mutex;
    QWaitCondition cond;
};

190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228
class RenderThreadEvent : public QEvent
{
public:
    RenderThreadEvent(QEvent::Type type) : QEvent(type) { }
};

class InitEvent : public RenderThreadEvent
{
public:
    static const QEvent::Type TYPE = QEvent::Type(QEvent::User + 1);
    InitEvent() : RenderThreadEvent(TYPE)
    { }
};

class RenderEvent : public RenderThreadEvent
{
public:
    static const QEvent::Type TYPE = QEvent::Type(QEvent::User + 2);
    RenderEvent(bool newlyExposed_) : RenderThreadEvent(TYPE), newlyExposed(newlyExposed_)
    { }
    bool newlyExposed;
};

class SurfaceCleanupEvent : public RenderThreadEvent
{
public:
    static const QEvent::Type TYPE = QEvent::Type(QEvent::User + 3);
    SurfaceCleanupEvent() : RenderThreadEvent(TYPE)
    { }
};

class CloseEvent : public RenderThreadEvent
{
public:
    static const QEvent::Type TYPE = QEvent::Type(QEvent::User + 4);
    CloseEvent() : RenderThreadEvent(TYPE)
    { }
};

229 230
struct Renderer
{
231 232
    // ctor and dtor and send* are called main thread, rest on the render thread

233 234 235
    Renderer(QWindow *w);
    ~Renderer();

236 237 238 239
    void sendInit();
    void sendRender(bool newlyExposed);
    void sendSurfaceGoingAway();

240 241 242 243 244 245 246 247 248 249
    QWindow *window;
    Thread *thread;
    QRhi *r = nullptr;
#ifndef QT_NO_OPENGL
    QOpenGLContext *context = nullptr;
    QOffscreenSurface *fallbackSurface = nullptr;
#endif

    void createRhi();
    void destroyRhi();
250 251 252 253 254 255 256 257 258 259 260
    void renderEvent(QEvent *e);
    void init();
    void releaseSwapChain();
    void releaseResources();
    void render(bool newlyExposed);

    QVector<QRhiResource *> m_releasePool;
    bool m_hasSwapChain = false;
    QRhiSwapChain *m_sc = nullptr;
    QRhiRenderBuffer *m_ds = nullptr;
    QRhiRenderPassDescriptor *m_rp = nullptr;
261 262 263 264 265
};

void Thread::run()
{
    while (active) {
266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286
        if (pendingRender) {
            pendingRender = false;
            renderer->render(pendingRenderIsNewExpose);
        }

        while (eventQueue.hasMoreEvents()) {
            QEvent *e = eventQueue.takeEvent(false);
            renderer->renderEvent(e);
            delete e;
        }

        if (active && !pendingRender) {
            sleeping = true;
            stopEventProcessing = false;
            while (!stopEventProcessing) {
                QEvent *e = eventQueue.takeEvent(true);
                renderer->renderEvent(e);
                delete e;
            }
            sleeping = false;
        }
287 288 289 290 291 292 293 294 295 296
    }

#ifndef QT_NO_OPENGL
    if (renderer->context)
        renderer->context->moveToThread(qGuiApp->thread());
#endif
}

Renderer::Renderer(QWindow *w)
    : window(w)
297
{ // main thread
298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315
    thread = new Thread(this);

#ifndef QT_NO_OPENGL
    if (graphicsApi == OpenGL) {
        context = new QOpenGLContext;
        if (!context->create())
            qFatal("Failed to get OpenGL context");

        fallbackSurface = new QOffscreenSurface;
        fallbackSurface->setFormat(context->format());
        fallbackSurface->create();

        context->moveToThread(thread);
    }
#endif
}

Renderer::~Renderer()
316 317
{ // main thread
    thread->eventQueue.addEvent(new CloseEvent);
318 319 320 321 322 323 324 325 326 327 328
    thread->wait();
    delete thread;

#ifndef QT_NO_OPENGL
    delete context;
    delete fallbackSurface;
#endif
}

void Renderer::createRhi()
{
329 330 331
    if (r)
        return;

332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371
#ifndef QT_NO_OPENGL
    if (graphicsApi == OpenGL) {
        QRhiGles2InitParams params;
        params.context = context;
        params.window = window;
        params.fallbackSurface = fallbackSurface;
        r = QRhi::create(QRhi::OpenGLES2, &params);
    }
#endif

#if QT_CONFIG(vulkan)
    if (graphicsApi == Vulkan) {
        QRhiVulkanInitParams params;
        params.inst = instance;
        params.window = window;
        r = QRhi::create(QRhi::Vulkan, &params);
    }
#endif

#ifdef Q_OS_WIN
    if (graphicsApi == D3D11) {
        QRhiD3D11InitParams params;
        r = QRhi::create(QRhi::D3D11, &params);
    }
#endif

#ifdef Q_OS_DARWIN
    if (graphicsApi == Metal) {
        QRhiMetalInitParams params;
        r = QRhi::create(QRhi::Metal, &params);
    }
#endif

    if (!r)
        qFatal("Failed to create RHI backend");
}

void Renderer::destroyRhi()
{
    delete r;
372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505
    r = nullptr;
}

void Renderer::renderEvent(QEvent *e)
{
    Q_ASSERT(QThread::currentThread() == thread);

    if (thread->sleeping)
        thread->stopEventProcessing = true;

    switch (e->type()) {
    case InitEvent::TYPE:
        qDebug() << "renderer" << this << "for window" << window << "is initializing";
        createRhi();
        init();
        break;
    case RenderEvent::TYPE:
        thread->pendingRender = true;
        thread->pendingRenderIsNewExpose = static_cast<RenderEvent *>(e)->newlyExposed;
        break;
    case SurfaceCleanupEvent::TYPE: // when the QWindow is closed, before QPlatformWindow goes away
        thread->mutex.lock();
        qDebug() << "renderer" << this << "for window" << window << "is destroying swapchain";
        releaseSwapChain();
        thread->cond.wakeOne();
        thread->mutex.unlock();
        break;
    case CloseEvent::TYPE: // when destroying the window+renderer (NB not the same as hitting X on the window, that's just QWindow close)
        qDebug() << "renderer" << this << "for window" << window << "is shutting down";
        thread->active = false;
        thread->stopEventProcessing = true;
        releaseResources();
        destroyRhi();
        break;
    default:
        break;
    }
}

void Renderer::init()
{
    m_sc = r->newSwapChain();
    m_ds = r->newRenderBuffer(QRhiRenderBuffer::DepthStencil,
                              QSize(), // no need to set the size yet
                              1,
                              QRhiRenderBuffer::ToBeUsedWithSwapChainOnly);
    m_releasePool << m_ds;
    m_sc->setWindow(window);
    m_sc->setDepthStencil(m_ds);
    m_rp = m_sc->newCompatibleRenderPassDescriptor();
    m_releasePool << m_rp;
    m_sc->setRenderPassDescriptor(m_rp);
}

void Renderer::releaseSwapChain()
{
    if (m_hasSwapChain) {
        m_hasSwapChain = false;
        m_sc->release();
    }
}

void Renderer::releaseResources()
{
    for (QRhiResource *res : m_releasePool)
        res->releaseAndDestroy();

    m_releasePool.clear();

    if (m_sc) {
        m_sc->releaseAndDestroy();
        m_sc = nullptr;
    }
}

void Renderer::render(bool newlyExposed)
{
    auto buildOrResizeSwapChain = [this] {
        qDebug() << "renderer" << this << "build or resize swapchain for window" << window;
        const QSize outputSize = m_sc->surfacePixelSize();
        qDebug() << "  size is" << outputSize;
        m_ds->setPixelSize(outputSize);
        m_ds->build();
        m_hasSwapChain = m_sc->buildOrResize();
    };

    if (newlyExposed || m_sc->currentPixelSize() != m_sc->surfacePixelSize())
        buildOrResizeSwapChain();

    if (!m_hasSwapChain)
        return;

    QRhi::FrameOpResult result = r->beginFrame(m_sc);
    if (result == QRhi::FrameOpSwapChainOutOfDate) {
        buildOrResizeSwapChain();
        if (!m_hasSwapChain)
            return;
        result = r->beginFrame(m_sc);
    }
    if (result != QRhi::FrameOpSuccess)
        return;

    QRhiCommandBuffer *cb = m_sc->currentFrameCommandBuffer();

    cb->beginPass(m_sc->currentFrameRenderTarget(), { 0.4f, 0.7f, 0.0f, 1.0f }, { 1.0f, 0 });
    cb->endPass();

    r->endFrame(m_sc);
}

void Renderer::sendInit()
{ // main thread
    InitEvent *e = new InitEvent;
    thread->eventQueue.addEvent(e);
}

void Renderer::sendRender(bool newlyExposed)
{ // main thread
    RenderEvent *e = new RenderEvent(newlyExposed);
    thread->eventQueue.addEvent(e);
}

void Renderer::sendSurfaceGoingAway()
{ // main thread
    SurfaceCleanupEvent *e = new SurfaceCleanupEvent;

    // cannot let this thread to proceed with tearing down the native window
    // before the render thread completes the swapchain release
    thread->mutex.lock();

    thread->eventQueue.addEvent(e);

    thread->cond.wait(&thread->mutex);
    thread->mutex.unlock();
506 507 508 509
}

class Window : public QWindow
{
510 511
    Q_OBJECT

512 513 514 515
public:
    Window(const QString &title, const QColor &bgColor, int axis);
    ~Window();

516 517 518 519 520 521 522 523
    void exposeEvent(QExposeEvent *) override;
    bool event(QEvent *) override;

signals:
    void initRequested();
    void renderRequested(bool newlyExposed);
    void surfaceGoingAway();

524 525 526
protected:
    QColor m_bgColor;
    int m_rotationAxis = 0;
527 528 529

    bool m_running = false;
    bool m_notExposed = true;
530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563
};

Window::Window(const QString &title, const QColor &bgColor, int axis)
    : m_bgColor(bgColor),
      m_rotationAxis(axis)
{
    switch (graphicsApi) {
    case OpenGL:
        setSurfaceType(OpenGLSurface);
        break;
    case Vulkan:
        setSurfaceType(VulkanSurface);
        setVulkanInstance(instance);
        break;
    case D3D11:
        setSurfaceType(OpenGLSurface); // not a typo
        break;
    case Metal:
#if (QT_VERSION >= QT_VERSION_CHECK(5, 12, 0))
        setSurfaceType(MetalSurface);
#endif
        break;
    default:
        break;
    }

    resize(800, 600);
    setTitle(title);
}

Window::~Window()
{
}

564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605
void Window::exposeEvent(QExposeEvent *)
{
    // initialize and start rendering when the window becomes usable for graphics purposes
    if (isExposed() && !m_running) {
        m_running = true;
        m_notExposed = false;
        emit initRequested();
        emit renderRequested(true);
    }

    // stop pushing frames when not exposed (on some platforms this is essential, optional on others)
    if (!isExposed() && m_running)
        m_notExposed = true;

    // continue when exposed again
    if (isExposed() && m_running && m_notExposed) {
        m_notExposed = false;
        emit renderRequested(true);
    }
}

bool Window::event(QEvent *e)
{
    switch (e->type()) {
    case QEvent::UpdateRequest:
        if (!m_notExposed)
            emit renderRequested(false);
        break;

    case QEvent::PlatformSurface:
        // this is the proper time to tear down the swapchain (while the native window and surface are still around)
        if (static_cast<QPlatformSurfaceEvent *>(e)->surfaceEventType() == QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed)
            emit surfaceGoingAway();
        break;

    default:
        break;
    }

    return QWindow::event(e);
}

606 607 608 609 610 611 612 613 614 615 616 617
struct WindowAndRenderer
{
    QWindow *window;
    Renderer *renderer;
};

QVector<WindowAndRenderer> windows;

void createWindow()
{
    static QColor colors[] = { Qt::red, Qt::green, Qt::blue, Qt::yellow, Qt::cyan, Qt::gray };
    const int n = windows.count();
618 619 620 621 622 623 624 625 626 627 628 629 630
    Window *w = new Window(QString::asprintf("Window #%d", n), colors[n % 6], n % 3);
    Renderer *renderer = new Renderer(w);
    QObject::connect(w, &Window::initRequested, w, [renderer] {
        renderer->sendInit();
    });
    QObject::connect(w, &Window::renderRequested, w, [w, renderer](bool newlyExposed) {
        renderer->sendRender(newlyExposed);
        w->requestUpdate();
    });
    QObject::connect(w, &Window::surfaceGoingAway, w, [renderer] {
        renderer->sendSurfaceGoingAway();
    });
    windows.append({ w, renderer });
631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
    w->show();
}

void closeWindow()
{
    WindowAndRenderer wr = windows.takeLast();
    delete wr.renderer;
    delete wr.window;
}

int main(int argc, char **argv)
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QApplication app(argc, argv);

#if defined(Q_OS_WIN)
    graphicsApi = D3D11;
#elif defined(Q_OS_DARWIN)
    graphicsApi = Metal;
#elif QT_CONFIG(vulkan)
    graphicsApi = Vulkan;
#else
    graphicsApi = OpenGL;
#endif

    QCommandLineParser cmdLineParser;
    cmdLineParser.addHelpOption();
    QCommandLineOption glOption({ "g", "opengl" }, QLatin1String("OpenGL (2.x)"));
    cmdLineParser.addOption(glOption);
    QCommandLineOption vkOption({ "v", "vulkan" }, QLatin1String("Vulkan"));
    cmdLineParser.addOption(vkOption);
    QCommandLineOption d3dOption({ "d", "d3d11" }, QLatin1String("Direct3D 11"));
    cmdLineParser.addOption(d3dOption);
    QCommandLineOption mtlOption({ "m", "metal" }, QLatin1String("Metal"));
    cmdLineParser.addOption(mtlOption);
    cmdLineParser.process(app);
    if (cmdLineParser.isSet(glOption))
        graphicsApi = OpenGL;
    if (cmdLineParser.isSet(vkOption))
        graphicsApi = Vulkan;
    if (cmdLineParser.isSet(d3dOption))
        graphicsApi = D3D11;
    if (cmdLineParser.isSet(mtlOption))
        graphicsApi = Metal;

    qDebug("Selected graphics API is %s", qPrintable(graphicsApiName()));
    qDebug("This is a multi-api example, use command line arguments to override:\n%s", qPrintable(cmdLineParser.helpText()));

    QSurfaceFormat fmt;
    fmt.setDepthBufferSize(24);
    fmt.setStencilBufferSize(8);
    QSurfaceFormat::setDefaultFormat(fmt);

#if QT_CONFIG(vulkan)
    instance = new QVulkanInstance;
    if (graphicsApi == Vulkan) {
#ifndef Q_OS_ANDROID
        instance->setLayers({ "VK_LAYER_LUNARG_standard_validation" });
#else
        instance->setLayers(QByteArrayList()
                       << "VK_LAYER_GOOGLE_threading"
                       << "VK_LAYER_LUNARG_parameter_validation"
                       << "VK_LAYER_LUNARG_object_tracker"
                       << "VK_LAYER_LUNARG_core_validation"
                       << "VK_LAYER_LUNARG_image"
                       << "VK_LAYER_LUNARG_swapchain"
                       << "VK_LAYER_GOOGLE_unique_objects");
#endif
        if (!instance->create()) {
            qWarning("Failed to create Vulkan instance, switching to OpenGL");
            graphicsApi = OpenGL;
        }
    }
#endif

    int winCount = 0;
    QWidget w;
    w.resize(800, 600);
    w.setWindowTitle(QCoreApplication::applicationName() + QLatin1String(" - ") + graphicsApiName());
    QVBoxLayout *layout = new QVBoxLayout(&w);

    QPlainTextEdit *info = new QPlainTextEdit(
713
                QLatin1String("This application tests rendering on a separate thread per window, with dedicated QRhi instances. " // ### still sharing the same graphics device where applicable
714
                              "No resources are shared across windows here. (so no synchronization mess) "
715 716 717
                              "\n\nNote that this is only safe with D3D/DXGI if the main (gui) thread is not blocked when issuing the Present."
                              "\n\nThis is the same concept as the Qt Quick Scenegraph's threaded render loop. This should allow rendering to the different windows "
                              "without unintentionally throttling each other's threads."
718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753
                              "\n\nUsing API: ") + graphicsApiName());
    info->setReadOnly(true);
    layout->addWidget(info);
    QLabel *label = new QLabel(QLatin1String("Window count: 0"));
    layout->addWidget(label);
    QPushButton *btn = new QPushButton(QLatin1String("New window"));
    QObject::connect(btn, &QPushButton::clicked, btn, [label, &winCount] {
        winCount += 1;
        label->setText(QString::asprintf("Window count: %d", winCount));
        createWindow();
    });
    layout->addWidget(btn);
    btn = new QPushButton(QLatin1String("Close window"));
    QObject::connect(btn, &QPushButton::clicked, btn, [label, &winCount] {
        if (winCount > 0) {
            winCount -= 1;
            label->setText(QString::asprintf("Window count: %d", winCount));
            closeWindow();
        }
    });
    layout->addWidget(btn);
    w.show();

    int result = app.exec();

    for (const WindowAndRenderer &wr : windows) {
        delete wr.renderer;
        delete wr.window;
    }

#if QT_CONFIG(vulkan)
    delete instance;
#endif

    return result;
}
754 755

#include "multiwindow_threaded.moc"