kwin/src/compositor.cpp

/*
    KWin - the KDE window manager
    This file is part of the KDE project.

    SPDX-FileCopyrightText: 2006 Lubos Lunak <l.lunak@kde.org>

    SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "compositor.h"

#include <config-kwin.h>

#include "core/output.h"
#include "core/outputbackend.h"
#include "core/outputlayer.h"
#include "core/renderlayer.h"
#include "core/renderloop.h"
#include "dbusinterface.h"
#include "effects.h"
#include "ftrace.h"
#include "platformsupport/scenes/opengl/openglbackend.h"
#include "platformsupport/scenes/qpainter/qpainterbackend.h"
#include "scene/cursordelegate_opengl.h"
#include "scene/cursordelegate_qpainter.h"
#include "scene/cursorscene.h"
#include "scene/itemrenderer_opengl.h"
#include "scene/itemrenderer_qpainter.h"
#include "scene/surfaceitem.h"
#include "scene/workspacescene_opengl.h"
#include "scene/workspacescene_qpainter.h"
#include "utils/common.h"
#include "wayland_server.h"
#include "workspace.h"

#include "libkwineffects/glplatform.h"

#include <KLocalizedString>
#if KWIN_BUILD_NOTIFICATIONS
#include <KNotification>
#endif
#include <KSelectionOwner>

#include <QQuickWindow>

#include <xcb/composite.h>

namespace KWin
{

Compositor *Compositor::s_compositor = nullptr;
Compositor *Compositor::self()
{
    return s_compositor;
}

class CompositorSelectionOwner : public KSelectionOwner
{
    Q_OBJECT
public:
    CompositorSelectionOwner(const char *selection)
        : KSelectionOwner(selection, kwinApp()->x11Connection(), kwinApp()->x11RootWindow())
        , m_owning(false)
    {
        connect(this, &CompositorSelectionOwner::lostOwnership,
                this, [this]() {
                    m_owning = false;
                });
    }
    bool owning() const
    {
        return m_owning;
    }
    void setOwning(bool own)
    {
        m_owning = own;
    }

private:
    bool m_owning;
};

Compositor::Compositor(QObject *workspace)
    : QObject(workspace)
{
    connect(options, &Options::configChanged, this, &Compositor::configChanged);
    connect(options, &Options::animationSpeedChanged, this, &Compositor::configChanged);

    // 2 sec which should be enough to restart the compositor.
    static const int compositorLostMessageDelay = 2000;

    m_releaseSelectionTimer.setSingleShot(true);
    m_releaseSelectionTimer.setInterval(compositorLostMessageDelay);
    connect(&m_releaseSelectionTimer, &QTimer::timeout,
            this, &Compositor::releaseCompositorSelection);

    m_unusedSupportPropertyTimer.setInterval(compositorLostMessageDelay);
    m_unusedSupportPropertyTimer.setSingleShot(true);
    connect(&m_unusedSupportPropertyTimer, &QTimer::timeout,
            this, &Compositor::deleteUnusedSupportProperties);

    // Delay the call to start by one event cycle.
    // The ctor of this class is invoked from the Workspace ctor, that means before
    // Workspace is completely constructed, so calling Workspace::self() would result
    // in undefined behavior. This is fixed by using a delayed invocation.
    QTimer::singleShot(0, this, &Compositor::start);

    // register DBus
    new CompositorDBusInterface(this);
    FTraceLogger::create();
}

Compositor::~Compositor()
{
    deleteUnusedSupportProperties();
    destroyCompositorSelection();
    s_compositor = nullptr;
}

bool Compositor::attemptOpenGLCompositing()
{
    // Some broken drivers crash on glXQuery() so to prevent constant KWin crashes:
    if (openGLCompositingIsBroken()) {
        qCWarning(KWIN_CORE) << "KWin has detected that your OpenGL library is unsafe to use";
        return false;
    }

    createOpenGLSafePoint(OpenGLSafePoint::PreInit);
    auto safePointScope = qScopeGuard([this]() {
        createOpenGLSafePoint(OpenGLSafePoint::PostInit);
    });

    std::unique_ptr<OpenGLBackend> backend = kwinApp()->outputBackend()->createOpenGLBackend();
    if (!backend) {
        return false;
    }
    if (!backend->isFailed()) {
        backend->init();
    }
    if (backend->isFailed()) {
        return false;
    }

    const QByteArray forceEnv = qgetenv("KWIN_COMPOSE");
    if (!forceEnv.isEmpty()) {
        if (qstrcmp(forceEnv, "O2") == 0 || qstrcmp(forceEnv, "O2ES") == 0) {
            qCDebug(KWIN_CORE) << "OpenGL 2 compositing enforced by environment variable";
        } else {
            // OpenGL 2 disabled by environment variable
            return false;
        }
    } else {
        if (GLPlatform::instance()->recommendedCompositor() < OpenGLCompositing) {
            qCDebug(KWIN_CORE) << "Driver does not recommend OpenGL compositing";
            return false;
        }
    }

    // We only support the OpenGL 2+ shader API, not GL_ARB_shader_objects
    if (!hasGLVersion(2, 0)) {
        qCDebug(KWIN_CORE) << "OpenGL 2.0 is not supported";
        return false;
    }

    m_scene = std::make_unique<WorkspaceSceneOpenGL>(backend.get());
    m_cursorScene = std::make_unique<CursorScene>(std::make_unique<ItemRendererOpenGL>());
    m_backend = std::move(backend);

    // set strict binding
    if (options->isGlStrictBindingFollowsDriver()) {
        options->setGlStrictBinding(!GLPlatform::instance()->supports(GLFeature::LooseBinding));
    }

    qCDebug(KWIN_CORE) << "OpenGL compositing has been successfully initialized";
    return true;
}

bool Compositor::attemptQPainterCompositing()
{
    std::unique_ptr<QPainterBackend> backend(kwinApp()->outputBackend()->createQPainterBackend());
    if (!backend || backend->isFailed()) {
        return false;
    }

    m_scene = std::make_unique<WorkspaceSceneQPainter>(backend.get());
    m_cursorScene = std::make_unique<CursorScene>(std::make_unique<ItemRendererQPainter>());
    m_backend = std::move(backend);

    qCDebug(KWIN_CORE) << "QPainter compositing has been successfully initialized";
    return true;
}

bool Compositor::setupStart()
{
    if (kwinApp()->isTerminating()) {
        // Don't start while KWin is terminating. An event to restart might be lingering
        // in the event queue due to graphics reset.
        return false;
    }
    if (m_state != State::Off) {
        return false;
    }
    m_state = State::Starting;

    if (kwinApp()->operationMode() == Application::OperationModeX11) {
        if (!m_selectionOwner) {
            m_selectionOwner = std::make_unique<CompositorSelectionOwner>("_NET_WM_CM_S0");
            connect(m_selectionOwner.get(), &CompositorSelectionOwner::lostOwnership, this, &Compositor::stop);
        }
        if (!m_selectionOwner->owning()) {
            // Force claim ownership.
            m_selectionOwner->claim(true);
            m_selectionOwner->setOwning(true);
        }

        xcb_composite_redirect_subwindows(kwinApp()->x11Connection(),
                                          kwinApp()->x11RootWindow(),
                                          XCB_COMPOSITE_REDIRECT_MANUAL);
    }

    Q_EMIT aboutToToggleCompositing();

    const QVector<CompositingType> availableCompositors = kwinApp()->outputBackend()->supportedCompositors();
    QVector<CompositingType> candidateCompositors;

    // If compositing has been restarted, try to use the last used compositing type.
    if (m_selectedCompositor != NoCompositing) {
        candidateCompositors.append(m_selectedCompositor);
    } else {
        candidateCompositors = availableCompositors;

        const auto userConfigIt = std::find(candidateCompositors.begin(), candidateCompositors.end(), options->compositingMode());
        if (userConfigIt != candidateCompositors.end()) {
            candidateCompositors.erase(userConfigIt);
            candidateCompositors.prepend(options->compositingMode());
        } else {
            qCWarning(KWIN_CORE) << "Configured compositor not supported by Platform. Falling back to defaults";
        }
    }

    for (auto type : std::as_const(candidateCompositors)) {
        bool stop = false;
        switch (type) {
        case OpenGLCompositing:
            qCDebug(KWIN_CORE) << "Attempting to load the OpenGL scene";
            stop = attemptOpenGLCompositing();
            break;
        case QPainterCompositing:
            qCDebug(KWIN_CORE) << "Attempting to load the QPainter scene";
            stop = attemptQPainterCompositing();
            break;
        case NoCompositing:
            qCDebug(KWIN_CORE) << "Starting without compositing...";
            stop = true;
            break;
        }

        if (stop) {
            break;
        } else if (qEnvironmentVariableIsSet("KWIN_COMPOSE")) {
            qCCritical(KWIN_CORE) << "Could not fulfill the requested compositing mode in KWIN_COMPOSE:" << type << ". Exiting.";
            qApp->quit();
        }
    }

    if (!m_backend) {
        m_state = State::Off;

        if (kwinApp()->operationMode() == Application::OperationModeX11) {
            xcb_composite_unredirect_subwindows(kwinApp()->x11Connection(),
                                                kwinApp()->x11RootWindow(),
                                                XCB_COMPOSITE_REDIRECT_MANUAL);
            if (m_selectionOwner) {
                m_selectionOwner->setOwning(false);
                m_selectionOwner->release();
            }
        }
        if (!availableCompositors.contains(NoCompositing)) {
            qCCritical(KWIN_CORE) << "The used windowing system requires compositing";
            qCCritical(KWIN_CORE) << "We are going to quit KWin now as it is broken";
            qApp->quit();
        }
        return false;
    }

    m_selectedCompositor = m_backend->compositingType();

    if (!Workspace::self() && m_backend && m_backend->compositingType() == QPainterCompositing) {
        // Force Software QtQuick on first startup with QPainter.
        QQuickWindow::setGraphicsApi(QSGRendererInterface::Software);
    }

    Q_EMIT sceneCreated();

    return true;
}

void Compositor::startupWithWorkspace()
{
    Q_ASSERT(m_scene);
    m_scene->initialize();
    m_cursorScene->initialize();

    const QList<Output *> outputs = workspace()->outputs();
    if (kwinApp()->operationMode() == Application::OperationModeX11) {
        auto workspaceLayer = new RenderLayer(outputs.constFirst()->renderLoop());
        workspaceLayer->setDelegate(std::make_unique<SceneDelegate>(m_scene.get(), nullptr));
        workspaceLayer->setGeometry(workspace()->geometry());
        connect(workspace(), &Workspace::geometryChanged, workspaceLayer, [workspaceLayer]() {
            workspaceLayer->setGeometry(workspace()->geometry());
        });
        addSuperLayer(workspaceLayer);
    } else {
        for (Output *output : outputs) {
            addOutput(output);
        }
        connect(workspace(), &Workspace::outputAdded, this, &Compositor::addOutput);
        connect(workspace(), &Workspace::outputRemoved, this, &Compositor::removeOutput);
    }

    m_state = State::On;

    const auto windows = workspace()->windows();
    for (Window *window : windows) {
        window->setupCompositing();
    }

    // Sets also the 'effects' pointer.
    kwinApp()->createEffectsHandler(this, m_scene.get());

    Q_EMIT compositingToggled(true);

    if (m_releaseSelectionTimer.isActive()) {
        m_releaseSelectionTimer.stop();
    }
}

Output *Compositor::findOutput(RenderLoop *loop) const
{
    const auto outputs = workspace()->outputs();
    for (Output *output : outputs) {
        if (output->renderLoop() == loop) {
            return output;
        }
    }
    return nullptr;
}

void Compositor::addOutput(Output *output)
{
    Q_ASSERT(kwinApp()->operationMode() != Application::OperationModeX11);

    auto workspaceLayer = new RenderLayer(output->renderLoop());
    workspaceLayer->setDelegate(std::make_unique<SceneDelegate>(m_scene.get(), output));
    workspaceLayer->setGeometry(output->rect());
    connect(output, &Output::geometryChanged, workspaceLayer, [output, workspaceLayer]() {
        workspaceLayer->setGeometry(output->rect());
    });

    auto cursorLayer = new RenderLayer(output->renderLoop());
    cursorLayer->setVisible(false);
    if (m_backend->compositingType() == OpenGLCompositing) {
        cursorLayer->setDelegate(std::make_unique<CursorDelegateOpenGL>(output));
    } else {
        cursorLayer->setDelegate(std::make_unique<CursorDelegateQPainter>(output));
    }
    cursorLayer->setParent(workspaceLayer);
    cursorLayer->setSuperlayer(workspaceLayer);

    static bool valid;
    static const bool forceSoftwareCursor = qEnvironmentVariableIntValue("KWIN_FORCE_SW_CURSOR", &valid) == 1 && valid;

    auto updateCursorLayer = [this, output, cursorLayer]() {
        const Cursor *cursor = Cursors::self()->currentCursor();
        const QRectF outputLocalRect = output->mapFromGlobal(cursor->geometry());
        const auto outputLayer = m_backend->cursorLayer(output);
        if (!cursor->isOnOutput(output)) {
            if (outputLayer && outputLayer->isEnabled()) {
                outputLayer->setEnabled(false);
                output->updateCursorLayer();
            }
            cursorLayer->setVisible(false);
            return true;
        }
        const auto renderHardwareCursor = [&]() {
            if (!outputLayer || forceSoftwareCursor) {
                return false;
            }
            const QMatrix4x4 monitorMatrix = Output::logicalToNativeMatrix(output->rect(), output->scale(), output->transform());
            QRectF nativeCursorRect = monitorMatrix.mapRect(outputLocalRect);
            QSize bufferSize(std::ceil(nativeCursorRect.width()), std::ceil(nativeCursorRect.height()));
            if (const auto fixedSize = outputLayer->fixedSize()) {
                if (fixedSize->width() < bufferSize.width() || fixedSize->height() < bufferSize.height()) {
                    return false;
                }
                bufferSize = *fixedSize;
                nativeCursorRect = monitorMatrix.mapRect(QRectF(outputLocalRect.topLeft(), QSizeF(bufferSize) / output->scale()));
            }
            outputLayer->setPosition(nativeCursorRect.topLeft());
            outputLayer->setHotspot(Output::logicalToNativeMatrix(QRectF(QPointF(), QSizeF(bufferSize) / output->scale()), output->scale(), output->transform()).map(cursor->hotspot()));
            outputLayer->setSize(bufferSize);
            if (auto beginInfo = outputLayer->beginFrame()) {
                const RenderTarget &renderTarget = beginInfo->renderTarget;

                RenderLayer renderLayer(output->renderLoop());
                renderLayer.setDelegate(std::make_unique<SceneDelegate>(m_cursorScene.get(), output));
                renderLayer.setOutputLayer(outputLayer);

                renderLayer.delegate()->prePaint();
                renderLayer.delegate()->paint(renderTarget, infiniteRegion());
                renderLayer.delegate()->postPaint();

                if (!outputLayer->endFrame(infiniteRegion(), infiniteRegion())) {
                    return false;
                }
            }
            outputLayer->setEnabled(true);
            return output->updateCursorLayer();
        };
        if (renderHardwareCursor()) {
            cursorLayer->setVisible(false);
            return true;
        } else {
            if (outputLayer && outputLayer->isEnabled()) {
                outputLayer->setEnabled(false);
                output->updateCursorLayer();
            }
            cursorLayer->setVisible(cursor->isOnOutput(output));
            cursorLayer->setGeometry(outputLocalRect);
            cursorLayer->addRepaintFull();
            return false;
        }
    };
    auto moveCursorLayer = [this, output, cursorLayer, updateCursorLayer]() {
        const Cursor *cursor = Cursors::self()->currentCursor();
        const QRectF outputLocalRect = output->mapFromGlobal(cursor->geometry());
        const auto outputLayer = m_backend->cursorLayer(output);
        bool hardwareCursor = false;
        if (outputLayer) {
            if (outputLayer->isEnabled()) {
                const QMatrix4x4 monitorMatrix = Output::logicalToNativeMatrix(output->rect(), output->scale(), output->transform());
                const QRectF nativeCursorRect = monitorMatrix.mapRect(QRectF(outputLocalRect.topLeft(), outputLayer->size() / output->scale()));
                outputLayer->setPosition(nativeCursorRect.topLeft());
                hardwareCursor = output->updateCursorLayer();
            } else if (!cursorLayer->isVisible() && !forceSoftwareCursor) {
                // this is for the case that the cursor wasn't visible because it was on a different output before
                hardwareCursor = updateCursorLayer();
            }
        }
        cursorLayer->setVisible(cursor->isOnOutput(output) && !hardwareCursor);
        cursorLayer->setGeometry(outputLocalRect);
        cursorLayer->addRepaintFull();
    };
    updateCursorLayer();
    connect(output, &Output::geometryChanged, cursorLayer, updateCursorLayer);
    connect(Cursors::self(), &Cursors::currentCursorChanged, cursorLayer, updateCursorLayer);
    connect(Cursors::self(), &Cursors::hiddenChanged, cursorLayer, updateCursorLayer);
    connect(Cursors::self(), &Cursors::positionChanged, cursorLayer, moveCursorLayer);

    addSuperLayer(workspaceLayer);
}

void Compositor::removeOutput(Output *output)
{
    removeSuperLayer(m_superlayers[output->renderLoop()]);
}

void Compositor::addSuperLayer(RenderLayer *layer)
{
    m_superlayers.insert(layer->loop(), layer);
    connect(layer->loop(), &RenderLoop::frameRequested, this, &Compositor::handleFrameRequested);
}

void Compositor::removeSuperLayer(RenderLayer *layer)
{
    m_superlayers.remove(layer->loop());
    disconnect(layer->loop(), &RenderLoop::frameRequested, this, &Compositor::handleFrameRequested);
    delete layer;
}

void Compositor::stop()
{
    if (m_state == State::Off || m_state == State::Stopping) {
        return;
    }
    m_state = State::Stopping;
    Q_EMIT aboutToToggleCompositing();

    m_releaseSelectionTimer.start();

    // Some effects might need access to effect windows when they are about to
    // be destroyed, for example to unreference deleted windows, so we have to
    // make sure that effect windows outlive effects.
    delete effects;
    effects = nullptr;

    if (Workspace::self()) {
        const auto windows = workspace()->windows();
        for (Window *window : windows) {
            window->finishCompositing();
        }
        if (kwinApp()->operationMode() == Application::OperationModeX11) {
            xcb_composite_unredirect_subwindows(kwinApp()->x11Connection(),
                                                kwinApp()->x11RootWindow(),
                                                XCB_COMPOSITE_REDIRECT_MANUAL);
        }

        disconnect(workspace(), &Workspace::outputAdded, this, &Compositor::addOutput);
        disconnect(workspace(), &Workspace::outputRemoved, this, &Compositor::removeOutput);
    }

    if (m_backend->compositingType() == OpenGLCompositing) {
        // some layers need a context current for destruction
        static_cast<OpenGLBackend *>(m_backend.get())->makeCurrent();
    }

    const auto superlayers = m_superlayers;
    for (auto it = superlayers.begin(); it != superlayers.end(); ++it) {
        removeSuperLayer(*it);
    }

    m_scene.reset();
    m_cursorScene.reset();
    m_backend.reset();

    m_state = State::Off;
    Q_EMIT compositingToggled(false);
}

void Compositor::destroyCompositorSelection()
{
    m_selectionOwner.reset();
}

void Compositor::releaseCompositorSelection()
{
    switch (m_state) {
    case State::On:
        // We are compositing at the moment. Don't release.
        break;
    case State::Off:
        if (m_selectionOwner) {
            qCDebug(KWIN_CORE) << "Releasing compositor selection";
            m_selectionOwner->setOwning(false);
            m_selectionOwner->release();
        }
        break;
    case State::Starting:
    case State::Stopping:
        // Still starting or shutting down the compositor. Starting might fail
        // or after stopping a restart might follow. So test again later on.
        m_releaseSelectionTimer.start();
        break;
    }
}

void Compositor::keepSupportProperty(xcb_atom_t atom)
{
    m_unusedSupportProperties.removeAll(atom);
}

void Compositor::removeSupportProperty(xcb_atom_t atom)
{
    m_unusedSupportProperties << atom;
    m_unusedSupportPropertyTimer.start();
}

void Compositor::deleteUnusedSupportProperties()
{
    if (m_state == State::Starting || m_state == State::Stopping) {
        // Currently still maybe restarting the compositor.
        m_unusedSupportPropertyTimer.start();
        return;
    }
    if (auto *con = kwinApp()->x11Connection()) {
        for (const xcb_atom_t &atom : std::as_const(m_unusedSupportProperties)) {
            // remove property from root window
            xcb_delete_property(con, kwinApp()->x11RootWindow(), atom);
        }
        m_unusedSupportProperties.clear();
    }
}

void Compositor::configChanged()
{
    reinitialize();
}

void Compositor::reinitialize()
{
    // Restart compositing
    stop();
    start();
}

void Compositor::handleFrameRequested(RenderLoop *renderLoop)
{
    composite(renderLoop);
}

uint Compositor::outputFormat(Output *output)
{
    OutputLayer *primaryLayer = m_backend->primaryLayer(output);
    return primaryLayer->format();
}

void Compositor::composite(RenderLoop *renderLoop)
{
    if (m_backend->checkGraphicsReset()) {
        qCDebug(KWIN_CORE) << "Graphics reset occurred";
#if KWIN_BUILD_NOTIFICATIONS
        KNotification::event(QStringLiteral("graphicsreset"), i18n("Desktop effects were restarted due to a graphics reset"));
#endif
        reinitialize();
        return;
    }

    Output *output = findOutput(renderLoop);
    OutputLayer *primaryLayer = m_backend->primaryLayer(output);
    fTraceDuration("Paint (", output->name(), ")");

    RenderLayer *superLayer = m_superlayers[renderLoop];
    superLayer->setOutputLayer(primaryLayer);

    renderLoop->prepareNewFrame();

    if (superLayer->needsRepaint()) {
        renderLoop->beginPaint();
        prePaintPass(superLayer);

        SurfaceItem *scanoutCandidate = superLayer->delegate()->scanoutCandidate();
        renderLoop->setFullscreenSurface(scanoutCandidate);
        output->setContentType(scanoutCandidate ? scanoutCandidate->contentType() : ContentType::None);

        bool directScanout = false;
        if (scanoutCandidate) {
            const auto sublayers = superLayer->sublayers();
            const bool scanoutPossible = std::none_of(sublayers.begin(), sublayers.end(), [](RenderLayer *sublayer) {
                return sublayer->isVisible();
            });
            if (scanoutPossible && !output->directScanoutInhibited()) {
                directScanout = primaryLayer->scanout(scanoutCandidate);
            }
        }

        if (!directScanout) {
            QRegion surfaceDamage = primaryLayer->repaints();
            primaryLayer->resetRepaints();
            preparePaintPass(superLayer, &surfaceDamage);

            if (auto beginInfo = primaryLayer->beginFrame()) {
                auto &[renderTarget, repaint] = beginInfo.value();

                const QRegion bufferDamage = surfaceDamage.united(repaint).intersected(superLayer->rect().toAlignedRect());

                paintPass(superLayer, renderTarget, bufferDamage);
                primaryLayer->endFrame(bufferDamage, surfaceDamage);
            }
        }

        postPaintPass(superLayer);
    }

    m_backend->present(output);

    framePass(superLayer);

    // TODO: Put it inside the cursor layer once the cursor layer can be backed by a real output layer.
    if (waylandServer()) {
        const std::chrono::milliseconds frameTime =
            std::chrono::duration_cast<std::chrono::milliseconds>(output->renderLoop()->lastPresentationTimestamp());

        if (!Cursors::self()->isCursorHidden()) {
            Cursor *cursor = Cursors::self()->currentCursor();
            if (cursor->geometry().intersects(output->geometry())) {
                cursor->markAsRendered(frameTime);
            }
        }
    }
}

void Compositor::framePass(RenderLayer *layer)
{
    layer->delegate()->frame();
    const auto sublayers = layer->sublayers();
    for (RenderLayer *sublayer : sublayers) {
        framePass(sublayer);
    }
}

void Compositor::prePaintPass(RenderLayer *layer)
{
    layer->delegate()->prePaint();
    const auto sublayers = layer->sublayers();
    for (RenderLayer *sublayer : sublayers) {
        prePaintPass(sublayer);
    }
}

void Compositor::postPaintPass(RenderLayer *layer)
{
    layer->delegate()->postPaint();
    const auto sublayers = layer->sublayers();
    for (RenderLayer *sublayer : sublayers) {
        postPaintPass(sublayer);
    }
}

void Compositor::preparePaintPass(RenderLayer *layer, QRegion *repaint)
{
    // TODO: Cull opaque region.
    *repaint += layer->mapToGlobal(layer->repaints() + layer->delegate()->repaints());
    layer->resetRepaints();
    const auto sublayers = layer->sublayers();
    for (RenderLayer *sublayer : sublayers) {
        if (sublayer->isVisible()) {
            preparePaintPass(sublayer, repaint);
        }
    }
}

void Compositor::paintPass(RenderLayer *layer, const RenderTarget &renderTarget, const QRegion &region)
{
    layer->delegate()->paint(renderTarget, region);

    const auto sublayers = layer->sublayers();
    for (RenderLayer *sublayer : sublayers) {
        if (sublayer->isVisible()) {
            paintPass(sublayer, renderTarget, region);
        }
    }
}

bool Compositor::isActive()
{
    return m_state == State::On;
}

bool Compositor::compositingPossible() const
{
    return true;
}

QString Compositor::compositingNotPossibleReason() const
{
    return QString();
}

bool Compositor::openGLCompositingIsBroken() const
{
    return false;
}

void Compositor::createOpenGLSafePoint(OpenGLSafePoint safePoint)
{
}

} // namespace KWin

// included for CompositorSelectionOwner
#include "compositor.moc"

#include "moc_compositor.cpp"