kwin/src/wayland/surface_interface.cpp

/********************************************************************
Copyright 2014  Martin Gräßlin <mgraesslin@kde.org>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) version 3, or any
later version accepted by the membership of KDE e.V. (or its
successor approved by the membership of KDE e.V.), which shall
act as a proxy defined in Section 6 of version 3 of the license.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/
#include "surface_interface.h"
#include "surface_interface_p.h"
#include "buffer_interface.h"
#include "clientconnection.h"
#include "compositor_interface.h"
#include "pointerconstraints_interface_p.h"
#include "region_interface.h"
#include "subcompositor_interface.h"
#include "subsurface_interface_p.h"
// Qt
#include <QListIterator>
// Wayland
#include <wayland-server.h>
// std
#include <algorithm>

namespace KWayland
{
namespace Server
{

SurfaceInterface::Private::Private(SurfaceInterface *q, CompositorInterface *c, wl_resource *parentResource)
    : Resource::Private(q, c, parentResource, &wl_surface_interface, &s_interface)
{
}

SurfaceInterface::Private::~Private()
{
    destroy();
}

void SurfaceInterface::Private::addChild(QPointer< SubSurfaceInterface > child)
{
    // protocol is not precise on how to handle the addition of new sub surfaces
    pending.children.append(child);
    subSurfacePending.children.append(child);
    current.children.append(child);
    Q_Q(SurfaceInterface);
    emit q->subSurfaceTreeChanged();
    QObject::connect(child.data(), &SubSurfaceInterface::positionChanged, q, &SurfaceInterface::subSurfaceTreeChanged);
    QObject::connect(child->surface().data(), &SurfaceInterface::damaged, q, &SurfaceInterface::subSurfaceTreeChanged);
    QObject::connect(child->surface().data(), &SurfaceInterface::unmapped, q, &SurfaceInterface::subSurfaceTreeChanged);
    QObject::connect(child->surface().data(), &SurfaceInterface::subSurfaceTreeChanged, q, &SurfaceInterface::subSurfaceTreeChanged);
}

void SurfaceInterface::Private::removeChild(QPointer< SubSurfaceInterface > child)
{
    // protocol is not precise on how to handle the addition of new sub surfaces
    pending.children.removeAll(child);
    subSurfacePending.children.removeAll(child);
    current.children.removeAll(child);
    Q_Q(SurfaceInterface);
    emit q->subSurfaceTreeChanged();
    QObject::disconnect(child.data(), &SubSurfaceInterface::positionChanged, q, &SurfaceInterface::subSurfaceTreeChanged);
    if (!child->surface().isNull()) {
        QObject::disconnect(child->surface().data(), &SurfaceInterface::damaged, q, &SurfaceInterface::subSurfaceTreeChanged);
        QObject::disconnect(child->surface().data(), &SurfaceInterface::unmapped, q, &SurfaceInterface::subSurfaceTreeChanged);
        QObject::disconnect(child->surface().data(), &SurfaceInterface::subSurfaceTreeChanged, q, &SurfaceInterface::subSurfaceTreeChanged);
    }
}

bool SurfaceInterface::Private::raiseChild(QPointer<SubSurfaceInterface> subsurface, SurfaceInterface *sibling)
{
    Q_Q(SurfaceInterface);
    auto it = std::find(pending.children.begin(), pending.children.end(), subsurface);
    if (it == pending.children.end()) {
        return false;
    }
    if (pending.children.count() == 1) {
        // nothing to do
        return true;
    }
    if (sibling == q) {
        // it's to the parent, so needs to become last item
        pending.children.append(*it);
        pending.children.erase(it);
        pending.childrenChanged = true;
        return true;
    }
    if (!sibling->subSurface()) {
        // not a sub surface
        return false;
    }
    auto siblingIt = std::find(pending.children.begin(), pending.children.end(), sibling->subSurface());
    if (siblingIt == pending.children.end() || siblingIt == it) {
        // not a sibling
        return false;
    }
    auto value = (*it);
    pending.children.erase(it);
    // find the iterator again
    siblingIt = std::find(pending.children.begin(), pending.children.end(), sibling->subSurface());
    pending.children.insert(++siblingIt, value);
    pending.childrenChanged = true;
    return true;
}

bool SurfaceInterface::Private::lowerChild(QPointer<SubSurfaceInterface> subsurface, SurfaceInterface *sibling)
{
    Q_Q(SurfaceInterface);
    auto it = std::find(pending.children.begin(), pending.children.end(), subsurface);
    if (it == pending.children.end()) {
        return false;
    }
    if (pending.children.count() == 1) {
        // nothing to do
        return true;
    }
    if (sibling == q) {
        // it's to the parent, so needs to become first item
        auto value = *it;
        pending.children.erase(it);
        pending.children.prepend(value);
        pending.childrenChanged = true;
        return true;
    }
    if (!sibling->subSurface()) {
        // not a sub surface
        return false;
    }
    auto siblingIt = std::find(pending.children.begin(), pending.children.end(), sibling->subSurface());
    if (siblingIt == pending.children.end() || siblingIt == it) {
        // not a sibling
        return false;
    }
    auto value = (*it);
    pending.children.erase(it);
    // find the iterator again
    siblingIt = std::find(pending.children.begin(), pending.children.end(), sibling->subSurface());
    pending.children.insert(siblingIt, value);
    pending.childrenChanged = true;
    return true;
}

void SurfaceInterface::Private::setShadow(const QPointer<ShadowInterface> &shadow)
{
    pending.shadow = shadow;
    pending.shadowIsSet = true;
}

void SurfaceInterface::Private::setBlur(const QPointer<BlurInterface> &blur)
{
    pending.blur = blur;
    pending.blurIsSet = true;
}

void SurfaceInterface::Private::setSlide(const QPointer<SlideInterface> &slide)
{
    pending.slide = slide;
    pending.slideIsSet = true;
}

void SurfaceInterface::Private::setContrast(const QPointer<ContrastInterface> &contrast)
{
    pending.contrast = contrast;
    pending.contrastIsSet = true;
}

void SurfaceInterface::Private::installPointerConstraint(LockedPointerInterface *lock)
{
    Q_ASSERT(lockedPointer.isNull());
    Q_ASSERT(confinedPointer.isNull());
    lockedPointer = QPointer<LockedPointerInterface>(lock);
    if (lock->lifeTime() == LockedPointerInterface::LifeTime::OneShot) {
        constrainsOneShotConnection = QObject::connect(lock, &LockedPointerInterface::lockedChanged, q_func(),
            [this] {
                if (lockedPointer.isNull()) {
                    return;
                }
                if (!lockedPointer->isLocked()) {
                    lockedPointer.clear();
                    disconnect(constrainsOneShotConnection);
                    constrainsOneShotConnection = QMetaObject::Connection();
                    disconnect(constrainsUnboundConnection);
                    constrainsUnboundConnection = QMetaObject::Connection();
                    emit q_func()->pointerConstraintsChanged();
                }
            }
        );
    }
    constrainsUnboundConnection = QObject::connect(lock, &LockedPointerInterface::unbound, q_func(),
        [this] {
            if (lockedPointer.isNull()) {
                return;
            }
            lockedPointer.clear();
            disconnect(constrainsOneShotConnection);
            constrainsOneShotConnection = QMetaObject::Connection();
            disconnect(constrainsUnboundConnection);
            constrainsUnboundConnection = QMetaObject::Connection();
            emit q_func()->pointerConstraintsChanged();
        }
    );
    emit q_func()->pointerConstraintsChanged();
}

void SurfaceInterface::Private::installPointerConstraint(ConfinedPointerInterface *confinement)
{
    Q_ASSERT(lockedPointer.isNull());
    Q_ASSERT(confinedPointer.isNull());
    confinedPointer = QPointer<ConfinedPointerInterface>(confinement);
    if (confinement->lifeTime() == ConfinedPointerInterface::LifeTime::OneShot) {
        constrainsOneShotConnection = QObject::connect(confinement, &ConfinedPointerInterface::confinedChanged, q_func(),
            [this] {
                if (confinedPointer.isNull()) {
                    return;
                }
                if (!confinedPointer->isConfined()) {
                    confinedPointer.clear();
                    disconnect(constrainsOneShotConnection);
                    constrainsOneShotConnection = QMetaObject::Connection();
                    disconnect(constrainsUnboundConnection);
                    constrainsUnboundConnection = QMetaObject::Connection();
                    emit q_func()->pointerConstraintsChanged();
                }
            }
        );
    }
    constrainsUnboundConnection = QObject::connect(confinement, &ConfinedPointerInterface::unbound, q_func(),
        [this] {
            if (confinedPointer.isNull()) {
                return;
            }
            confinedPointer.clear();
            disconnect(constrainsOneShotConnection);
            constrainsOneShotConnection = QMetaObject::Connection();
            disconnect(constrainsUnboundConnection);
            constrainsUnboundConnection = QMetaObject::Connection();
            emit q_func()->pointerConstraintsChanged();
        }
    );
    emit q_func()->pointerConstraintsChanged();
}

#ifndef DOXYGEN_SHOULD_SKIP_THIS
const struct wl_surface_interface SurfaceInterface::Private::s_interface = {
    resourceDestroyedCallback,
    attachCallback,
    damageCallback,
    frameCallaback,
    opaqueRegionCallback,
    inputRegionCallback,
    commitCallback,
    bufferTransformCallback,
    bufferScaleCallback
};
#endif

SurfaceInterface::SurfaceInterface(CompositorInterface *parent, wl_resource *parentResource)
    : Resource(new Private(this, parent, parentResource))
{
}

SurfaceInterface::~SurfaceInterface() = default;

void SurfaceInterface::frameRendered(quint32 msec)
{
    Q_D();
    // notify all callbacks
    const bool needsFlush = !d->current.callbacks.isEmpty();
    while (!d->current.callbacks.isEmpty()) {
        wl_resource *r = d->current.callbacks.takeFirst();
        wl_callback_send_done(r, msec);
        wl_resource_destroy(r);
    }
    for (auto it = d->current.children.constBegin(); it != d->current.children.constEnd(); ++it) {
        const auto &subSurface = *it;
        if (subSurface.isNull() || subSurface->d_func()->surface.isNull()) {
            continue;
        }
        subSurface->d_func()->surface->frameRendered(msec);
    }
    if (needsFlush)  {
        client()->flush();
    }
}

void SurfaceInterface::Private::destroy()
{
    // copy all existing callbacks to new list and clear existing lists
    // the wl_resource_destroy on the callback resource goes into destroyFrameCallback
    // which would modify the list we are iterating on
    QList<wl_resource *> callbacksToDestroy;
    callbacksToDestroy << current.callbacks;
    current.callbacks.clear();
    callbacksToDestroy << pending.callbacks;
    pending.callbacks.clear();
    callbacksToDestroy << subSurfacePending.callbacks;
    subSurfacePending.callbacks.clear();
    for (auto it = callbacksToDestroy.constBegin(), end = callbacksToDestroy.constEnd(); it != end; it++) {
        wl_resource_destroy(*it);
    }
    if (current.buffer) {
        current.buffer->unref();
    }
}

void SurfaceInterface::Private::swapStates(State *source, State *target, bool emitChanged)
{
    Q_Q(SurfaceInterface);
    bool bufferChanged = source->bufferIsSet;
    const bool opaqueRegionChanged = source->opaqueIsSet;
    const bool inputRegionChanged = source->inputIsSet;
    const bool scaleFactorChanged = source->scaleIsSet && (target->scale != source->scale);
    const bool transformChanged = source->transformIsSet && (target->transform != source->transform);
    const bool shadowChanged = source->shadowIsSet;
    const bool blurChanged = source->blurIsSet;
    const bool contrastChanged = source->contrastIsSet;
    const bool slideChanged = source->slideIsSet;
    const bool childrenChanged = source->childrenChanged;
    bool sizeChanged = false;
    auto buffer = target->buffer;
    if (bufferChanged) {
        // TODO: is the reffing correct for subsurfaces?
        QSize oldSize;
        if (target->buffer) {
            oldSize = target->buffer->size();
            if (emitChanged) {
                target->buffer->unref();
                QObject::disconnect(target->buffer, &BufferInterface::sizeChanged, q, &SurfaceInterface::sizeChanged);
            } else {
                delete target->buffer;
                target->buffer = nullptr;
            }
        }
        if (source->buffer) {
            if (emitChanged) {
                source->buffer->ref();
                QObject::connect(source->buffer, &BufferInterface::sizeChanged, q, &SurfaceInterface::sizeChanged);
            }
            const QSize newSize = source->buffer->size();
            sizeChanged = newSize.isValid() && newSize != oldSize;
        }
        if (!target->buffer && !source->buffer && emitChanged) {
            // null buffer set on a not mapped surface, don't emit unmapped
            bufferChanged = false;
        }
        buffer = source->buffer;
    }
    // copy values
    if (bufferChanged) {
        target->buffer = buffer;
        target->damage = source->damage;
        target->bufferIsSet = source->bufferIsSet;
    }
    if (childrenChanged) {
        target->childrenChanged = source->childrenChanged;
        target->children = source->children;
    }
    target->callbacks.append(source->callbacks);

    if (shadowChanged) {
        target->shadow = source->shadow;
        target->shadowIsSet = true;
    }
    if (blurChanged) {
        target->blur = source->blur;
        target->blurIsSet = true;
    }
    if (contrastChanged) {
        target->contrast = source->contrast;
        target->contrastIsSet = true;
    }
    if (slideChanged) {
        target->slide = source->slide;
        target->slideIsSet = true;
    }
    if (inputRegionChanged) {
        target->input = source->input;
        target->inputIsInfinite = source->inputIsInfinite;
        target->inputIsSet = true;
    }
    if (opaqueRegionChanged) {
        target->opaque = source->opaque;
        target->opaqueIsSet = true;
    }
    if (scaleFactorChanged) {
        target->scale = source->scale;
        target->scaleIsSet = true;
    }
    if (transformChanged) {
        target->transform = source->transform;
        target->transformIsSet = true;
    }
    if (!lockedPointer.isNull()) {
        lockedPointer->d_func()->commit();
    }
    if (!confinedPointer.isNull()) {
        confinedPointer->d_func()->commit();
    }

    *source = State{};
    source->children = target->children;
    if (opaqueRegionChanged) {
        emit q->opaqueChanged(target->opaque);
    }
    if (inputRegionChanged) {
        emit q->inputChanged(target->input);
    }
    if (scaleFactorChanged) {
        emit q->scaleChanged(target->scale);
        if (buffer && !sizeChanged) {
            emit q->sizeChanged();
        }
    }
    if (transformChanged) {
        emit q->transformChanged(target->transform);
    }
    if (bufferChanged && emitChanged) {
        if (!target->damage.isEmpty()) {
            const QRegion windowRegion = QRegion(0, 0, q->size().width(), q->size().height());
            if (!windowRegion.isEmpty()) {
                target->damage = windowRegion.intersected(target->damage);
                if (emitChanged) {
                    subSurfaceIsMapped = true;
                    trackedDamage = trackedDamage.united(target->damage);
                    emit q->damaged(target->damage);
                    // workaround for https://bugreports.qt.io/browse/QTBUG-52092
                    // if the surface is a sub-surface, but the main surface is not yet mapped, fake frame rendered
                    if (subSurface && !subSurface->mainSurface()->buffer()) {
                        q->frameRendered(0);
                    }
                }
            }
        } else if (!target->buffer && emitChanged) {
            subSurfaceIsMapped = false;
            emit q->unmapped();
        }
    }
    if (!emitChanged) {
        return;
    }
    if (sizeChanged) {
        emit q->sizeChanged();
    }
    if (shadowChanged) {
        emit q->shadowChanged();
    }
    if (blurChanged) {
        emit q->blurChanged();
    }
    if (contrastChanged) {
        emit q->contrastChanged();
    }
    if (slideChanged) {
        emit q->slideOnShowHideChanged();
    }
    if (childrenChanged) {
        emit q->subSurfaceTreeChanged();
    }
}

void SurfaceInterface::Private::commit()
{
    if (!subSurface.isNull() && subSurface->isSynchronized()) {
        swapStates(&pending, &subSurfacePending, false);
    } else {
        swapStates(&pending, &current, true);
        if (!subSurface.isNull()) {
            subSurface->d_func()->commit();
        }
        // commit all subSurfaces to apply position changes
        // "The cached state is applied to the sub-surface immediately after the parent surface's state is applied"
        for (auto it = current.children.constBegin(); it != current.children.constEnd(); ++it) {
            const auto &subSurface = *it;
            if (subSurface.isNull()) {
                continue;
            }
            subSurface->d_func()->commit();
        }
    }
}

void SurfaceInterface::Private::commitSubSurface()
{
    if (subSurface.isNull() || !subSurface->isSynchronized()) {
        return;
    }
    swapStates(&subSurfacePending, &current, true);
    // "The cached state is applied to the sub-surface immediately after the parent surface's state is applied"
    for (auto it = current.children.constBegin(); it != current.children.constEnd(); ++it) {
        const auto &subSurface = *it;
        if (subSurface.isNull() || !subSurface->isSynchronized()) {
            continue;
        }
        subSurface->d_func()->commit();
    }
}

void SurfaceInterface::Private::damage(const QRect &rect)
{
    if (!pending.bufferIsSet || (pending.bufferIsSet && !pending.buffer)) {
        // TODO: should we send an error?
        return;
    }
    pending.damage = pending.damage.united(rect);
}

void SurfaceInterface::Private::setScale(qint32 scale)
{
    pending.scale = scale;
    pending.scaleIsSet = true;
}

void SurfaceInterface::Private::setTransform(OutputInterface::Transform transform)
{
    pending.transform = transform;
}

void SurfaceInterface::Private::addFrameCallback(uint32_t callback)
{
    wl_resource *r = client->createResource(&wl_callback_interface, 1, callback);
    if (!r) {
        wl_resource_post_no_memory(resource);
        return;
    }
    wl_resource_set_implementation(r, nullptr, this, destroyFrameCallback);
    pending.callbacks << r;
}

void SurfaceInterface::Private::attachBuffer(wl_resource *buffer, const QPoint &offset)
{
    pending.bufferIsSet = true;
    pending.offset = offset;
    if (pending.buffer) {
        delete pending.buffer;
    }
    if (!buffer) {
        // got a null buffer, deletes content in next frame
        pending.buffer = nullptr;
        pending.damage = QRegion();
        return;
    }
    Q_Q(SurfaceInterface);
    pending.buffer = new BufferInterface(buffer, q);
    QObject::connect(pending.buffer, &BufferInterface::aboutToBeDestroyed, q,
        [this](BufferInterface *buffer) {
            if (pending.buffer == buffer) {
                pending.buffer = nullptr;
            }
            if (subSurfacePending.buffer == buffer) {
                subSurfacePending.buffer = nullptr;
            }
            if (current.buffer == buffer) {
                current.buffer->unref();
                current.buffer = nullptr;
            }
        }
    );
}

void SurfaceInterface::Private::destroyFrameCallback(wl_resource *r)
{
    auto s = cast<Private>(r);
    s->current.callbacks.removeAll(r);
    s->pending.callbacks.removeAll(r);
    s->subSurfacePending.callbacks.removeAll(r);
}

void SurfaceInterface::Private::attachCallback(wl_client *client, wl_resource *resource, wl_resource *buffer, int32_t sx, int32_t sy)
{
    Q_UNUSED(client)
    cast<Private>(resource)->attachBuffer(buffer, QPoint(sx, sy));
}

void SurfaceInterface::Private::damageCallback(wl_client *client, wl_resource *resource, int32_t x, int32_t y, int32_t width, int32_t height)
{
    Q_UNUSED(client)
    cast<Private>(resource)->damage(QRect(x, y, width, height));
}

void SurfaceInterface::Private::frameCallaback(wl_client *client, wl_resource *resource, uint32_t callback)
{
    auto s = cast<Private>(resource);
    Q_ASSERT(client == *s->client);
    s->addFrameCallback(callback);
}

void SurfaceInterface::Private::opaqueRegionCallback(wl_client *client, wl_resource *resource, wl_resource *region)
{
    auto s = cast<Private>(resource);
    Q_ASSERT(client == *s->client);
    auto r = RegionInterface::get(region);
    s->setOpaque(r ? r->region() : QRegion());
}

void SurfaceInterface::Private::setOpaque(const QRegion &region)
{
    pending.opaqueIsSet = true;
    pending.opaque = region;
}

void SurfaceInterface::Private::inputRegionCallback(wl_client *client, wl_resource *resource, wl_resource *region)
{
    auto s = cast<Private>(resource);
    Q_ASSERT(client == *s->client);
    auto r = RegionInterface::get(region);
    s->setInput(r ? r->region() : QRegion(), !r);
}

void SurfaceInterface::Private::setInput(const QRegion &region, bool isInfinite)
{
    pending.inputIsSet = true;
    pending.inputIsInfinite = isInfinite;
    pending.input = region;
}

void SurfaceInterface::Private::commitCallback(wl_client *client, wl_resource *resource)
{
    Q_UNUSED(client)
    cast<Private>(resource)->commit();
}

void SurfaceInterface::Private::bufferTransformCallback(wl_client *client, wl_resource *resource, int32_t transform)
{
    Q_UNUSED(client)
    cast<Private>(resource)->setTransform(OutputInterface::Transform(transform));
}

void SurfaceInterface::Private::bufferScaleCallback(wl_client *client, wl_resource *resource, int32_t scale)
{
    Q_UNUSED(client)
    cast<Private>(resource)->setScale(scale);
}

QRegion SurfaceInterface::damage() const
{
    Q_D();
    return d->current.damage;
}

QRegion SurfaceInterface::opaque() const
{
    Q_D();
    return d->current.opaque;
}

QRegion SurfaceInterface::input() const
{
    Q_D();
    return d->current.input;
}

bool SurfaceInterface::inputIsInfitine() const
{
    return inputIsInfinite();
}

bool SurfaceInterface::inputIsInfinite() const
{
    Q_D();
    return d->current.inputIsInfinite;
}

qint32 SurfaceInterface::scale() const
{
    Q_D();
    return d->current.scale;
}

OutputInterface::Transform SurfaceInterface::transform() const
{
    Q_D();
    return d->current.transform;
}

BufferInterface *SurfaceInterface::buffer()
{
    Q_D();
    return d->current.buffer;
}

QPoint SurfaceInterface::offset() const
{
    Q_D();
    return d->current.offset;
}

SurfaceInterface *SurfaceInterface::get(wl_resource *native)
{
    return Private::get<SurfaceInterface>(native);
}

SurfaceInterface *SurfaceInterface::get(quint32 id, const ClientConnection *client)
{
    return Private::get<SurfaceInterface>(id, client);
}

QList< QPointer< SubSurfaceInterface > > SurfaceInterface::childSubSurfaces() const
{
    Q_D();
    return d->current.children;
}

QPointer< SubSurfaceInterface > SurfaceInterface::subSurface() const
{
    Q_D();
    return d->subSurface;
}

QSize SurfaceInterface::size() const
{
    Q_D();
    // TODO: apply transform to the buffer size
    if (d->current.buffer) {
        return d->current.buffer->size() / scale();
    }
    return QSize();
}

QPointer< ShadowInterface > SurfaceInterface::shadow() const
{
    Q_D();
    return d->current.shadow;
}

QPointer< BlurInterface > SurfaceInterface::blur() const
{
    Q_D();
    return d->current.blur;
}

QPointer< ContrastInterface > SurfaceInterface::contrast() const
{
    Q_D();
    return d->current.contrast;
}

QPointer< SlideInterface > SurfaceInterface::slideOnShowHide() const
{
    Q_D();
    return d->current.slide;
}

bool SurfaceInterface::isMapped() const
{
    Q_D();
    if (d->subSurface) {
        // from spec:
        // "A sub-surface becomes mapped, when a non-NULL wl_buffer is applied and the parent surface is mapped."
        return d->subSurfaceIsMapped && !d->subSurface->parentSurface().isNull() && d->subSurface->parentSurface()->isMapped();
    }
    return d->current.buffer != nullptr;
}

QRegion SurfaceInterface::trackedDamage() const
{
    Q_D();
    return d->trackedDamage;
}

void SurfaceInterface::resetTrackedDamage()
{
    Q_D();
    d->trackedDamage = QRegion();
}

QVector<OutputInterface *> SurfaceInterface::outputs() const
{
    Q_D();
    return d->outputs;
}

void SurfaceInterface::setOutputs(const QVector<OutputInterface *> &outputs)
{
    Q_D();
    QVector<OutputInterface *> removedOutputs = d->outputs;
    for (auto it = outputs.constBegin(), end = outputs.constEnd(); it != end; ++it) {
        const auto o = *it;
        removedOutputs.removeOne(o);
    }
    for (auto it = removedOutputs.constBegin(), end = removedOutputs.constEnd(); it != end; ++it) {
        const auto resources = (*it)->clientResources(client());
        for (wl_resource *r : resources) {
            wl_surface_send_leave(d->resource, r);
        }
    }
    // TODO: send leave when OutputInterface gets destroyed

    QVector<OutputInterface *> addedOutputsOutputs = outputs;
    for (auto it = d->outputs.constBegin(), end = d->outputs.constEnd(); it != end; ++it) {
        const auto o = *it;
        addedOutputsOutputs.removeOne(o);
    }
    for (auto it = addedOutputsOutputs.constBegin(), end = addedOutputsOutputs.constEnd(); it != end; ++it) {
        const auto resources = (*it)->clientResources(client());
        for (wl_resource *r : resources) {
            wl_surface_send_enter(d->resource, r);
        }
    }
    // TODO: send enter when the client binds the OutputInterface another time

    d->outputs = outputs;
}

SurfaceInterface *SurfaceInterface::surfaceAt(const QPointF &position)
{
    if (!isMapped()) {
        return nullptr;
    }
    Q_D();
    // go from top to bottom. Top most child is last in list
    QListIterator<QPointer<SubSurfaceInterface>> it(d->current.children);
    it.toBack();
    while (it.hasPrevious()) {
        const auto &current = it.previous();
        auto surface = current->surface();
        if (surface.isNull()) {
            continue;
        }
        if (auto s = surface->surfaceAt(position - current->position())) {
            return s;
        }
    }
    // check whether the geometry contains the pos
    if (!size().isEmpty() && QRectF(QPoint(0, 0), size()).contains(position)) {
        return this;
    }
    return nullptr;
}

QPointer<LockedPointerInterface> SurfaceInterface::lockedPointer() const
{
    Q_D();
    return d->lockedPointer;
}

QPointer<ConfinedPointerInterface> SurfaceInterface::confinedPointer() const
{
    Q_D();
    return d->confinedPointer;
}

SurfaceInterface::Private *SurfaceInterface::d_func() const
{
    return reinterpret_cast<Private*>(d.data());
}

}
}