Brooklyn/plasma/workspace/libtaskmanager/waylandtasksmodel.cpp

/*
    SPDX-FileCopyrightText: 2016 Eike Hein <[email protected]>

    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
*/

#include "waylandtasksmodel.h"
#include "tasktools.h"
#include "virtualdesktopinfo.h"

#include <KDirWatch>
#include <KSharedConfig>
#include <KWayland/Client/connection_thread.h>
#include <KWayland/Client/plasmawindowmanagement.h>
#include <KWayland/Client/registry.h>
#include <KWayland/Client/surface.h>
#include <KWindowSystem>

#include <QGuiApplication>
#include <QMimeData>
#include <QQuickItem>
#include <QQuickWindow>
#include <QSet>
#include <QUrl>
#include <QUuid>
#include <QWindow>

namespace TaskManager
{
class Q_DECL_HIDDEN WaylandTasksModel::Private
{
public:
    Private(WaylandTasksModel *q);
    QList<KWayland::Client::PlasmaWindow *> windows;
    QHash<KWayland::Client::PlasmaWindow *, AppData> appDataCache;
    QHash<KWayland::Client::PlasmaWindow *, QTime> lastActivated;
    KWayland::Client::PlasmaWindowManagement *windowManagement = nullptr;
    KSharedConfig::Ptr rulesConfig;
    KDirWatch *configWatcher = nullptr;
    VirtualDesktopInfo *virtualDesktopInfo = nullptr;
    static QUuid uuid;

    void init();
    void initWayland();
    void addWindow(KWayland::Client::PlasmaWindow *window);

    AppData appData(KWayland::Client::PlasmaWindow *window);

    QIcon icon(KWayland::Client::PlasmaWindow *window);

    static QString mimeType();
    static QString groupMimeType();

    void dataChanged(KWayland::Client::PlasmaWindow *window, int role);
    void dataChanged(KWayland::Client::PlasmaWindow *window, const QVector<int> &roles);

private:
    WaylandTasksModel *q;
};

QUuid WaylandTasksModel::Private::uuid = QUuid::createUuid();

WaylandTasksModel::Private::Private(WaylandTasksModel *q)
    : q(q)
{
}

void WaylandTasksModel::Private::init()
{
    auto clearCacheAndRefresh = [this] {
        if (!windows.count()) {
            return;
        }

        appDataCache.clear();

        // Emit changes of all roles satisfied from app data cache.
        Q_EMIT q->dataChanged(q->index(0, 0),
                              q->index(windows.count() - 1, 0),
                              QVector<int>{Qt::DecorationRole,
                                           AbstractTasksModel::AppId,
                                           AbstractTasksModel::AppName,
                                           AbstractTasksModel::GenericName,
                                           AbstractTasksModel::LauncherUrl,
                                           AbstractTasksModel::LauncherUrlWithoutIcon,
                                           AbstractTasksModel::CanLaunchNewInstance,
                                           AbstractTasksModel::SkipTaskbar});
    };

    rulesConfig = KSharedConfig::openConfig(QStringLiteral("taskmanagerrulesrc"));
    configWatcher = new KDirWatch(q);

    foreach (const QString &location, QStandardPaths::standardLocations(QStandardPaths::ConfigLocation)) {
        configWatcher->addFile(location + QLatin1String("/taskmanagerrulesrc"));
    }

    auto rulesConfigChange = [this, clearCacheAndRefresh] {
        rulesConfig->reparseConfiguration();
        clearCacheAndRefresh();
    };

    QObject::connect(configWatcher, &KDirWatch::dirty, rulesConfigChange);
    QObject::connect(configWatcher, &KDirWatch::created, rulesConfigChange);
    QObject::connect(configWatcher, &KDirWatch::deleted, rulesConfigChange);

    virtualDesktopInfo = new VirtualDesktopInfo(q);

    initWayland();
}

void WaylandTasksModel::Private::initWayland()
{
    if (!KWindowSystem::isPlatformWayland()) {
        return;
    }

    KWayland::Client::ConnectionThread *connection = KWayland::Client::ConnectionThread::fromApplication(q);

    if (!connection) {
        return;
    }

    KWayland::Client::Registry *registry = new KWayland::Client::Registry(q);
    registry->create(connection);

    QObject::connect(registry, &KWayland::Client::Registry::plasmaWindowManagementAnnounced, q, [this, registry](quint32 name, quint32 version) {
        windowManagement = registry->createPlasmaWindowManagement(name, version, q);

        QObject::connect(windowManagement, &KWayland::Client::PlasmaWindowManagement::interfaceAboutToBeReleased, q, [this] {
            q->beginResetModel();
            windows.clear();
            q->endResetModel();
        });

        QObject::connect(windowManagement, &KWayland::Client::PlasmaWindowManagement::windowCreated, q, [this](KWayland::Client::PlasmaWindow *window) {
            addWindow(window);
        });

        QObject::connect(windowManagement, &KWayland::Client::PlasmaWindowManagement::stackingOrderUuidsChanged, q, [this]() {
            for (const auto window : qAsConst(windows)) {
                this->dataChanged(window, StackingOrder);
            }
        });

        const auto windows = windowManagement->windows();
        for (auto it = windows.constBegin(); it != windows.constEnd(); ++it) {
            addWindow(*it);
        }
    });

    registry->setup();
}

void WaylandTasksModel::Private::addWindow(KWayland::Client::PlasmaWindow *window)
{
    if (windows.indexOf(window) != -1) {
        return;
    }

    const int count = windows.count();

    q->beginInsertRows(QModelIndex(), count, count);

    windows.append(window);

    q->endInsertRows();

    auto removeWindow = [window, this] {
        const int row = windows.indexOf(window);
        if (row != -1) {
            q->beginRemoveRows(QModelIndex(), row, row);
            windows.removeAt(row);
            appDataCache.remove(window);
            lastActivated.remove(window);
            q->endRemoveRows();
        }
    };

    QObject::connect(window, &KWayland::Client::PlasmaWindow::unmapped, q, removeWindow);
    QObject::connect(window, &QObject::destroyed, q, removeWindow);

    QObject::connect(window, &KWayland::Client::PlasmaWindow::titleChanged, q, [window, this] {
        this->dataChanged(window, Qt::DisplayRole);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::iconChanged, q, [window, this] {
        // The icon in the AppData struct might come from PlasmaWindow if it wasn't
        // filled in by windowUrlFromMetadata+appDataFromUrl.
        // TODO: Don't evict the cache unnecessarily if this isn't the case. As icons
        // are currently very static on Wayland, this eviction is unlikely to happen
        // frequently as of now.
        appDataCache.remove(window);

        this->dataChanged(window, Qt::DecorationRole);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::appIdChanged, q, [window, this] {
        // The AppData struct in the cache is derived from this and needs
        // to be evicted in favor of a fresh struct based on the changed
        // window metadata.
        appDataCache.remove(window);

        // Refresh roles satisfied from the app data cache.
        this->dataChanged(window, QVector<int>{AppId, AppName, GenericName, LauncherUrl, LauncherUrlWithoutIcon, SkipTaskbar, CanLaunchNewInstance});
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::activeChanged, q, [window, this] {
        if (window->isActive()) {
            lastActivated[window] = QTime::currentTime();
        }
        this->dataChanged(window, IsActive);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::closeableChanged, q, [window, this] {
        this->dataChanged(window, IsClosable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::movableChanged, q, [window, this] {
        this->dataChanged(window, IsMovable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::resizableChanged, q, [window, this] {
        this->dataChanged(window, IsResizable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::fullscreenableChanged, q, [window, this] {
        this->dataChanged(window, IsFullScreenable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::fullscreenChanged, q, [window, this] {
        this->dataChanged(window, IsFullScreen);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::maximizeableChanged, q, [window, this] {
        this->dataChanged(window, IsMaximizable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::maximizedChanged, q, [window, this] {
        this->dataChanged(window, IsMaximized);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::minimizeableChanged, q, [window, this] {
        this->dataChanged(window, IsMinimizable);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::minimizedChanged, q, [window, this] {
        this->dataChanged(window, IsMinimized);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::keepAboveChanged, q, [window, this] {
        this->dataChanged(window, IsKeepAbove);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::keepBelowChanged, q, [window, this] {
        this->dataChanged(window, IsKeepBelow);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::shadeableChanged, q, [window, this] {
        this->dataChanged(window, IsShadeable);
    });

    // FIXME
    //     QObject::connect(window, &KWayland::Client::PlasmaWindow::virtualDesktopChangeableChanged, q,
    //         // TODO: This is marked deprecated in KWayland, but (IMHO) shouldn't be.
    //         [window, this] { this->dataChanged(window, IsVirtualDesktopsChangeable); }
    //     );

    QObject::connect(window, &KWayland::Client::PlasmaWindow::plasmaVirtualDesktopEntered, q, [window, this] {
        this->dataChanged(window, VirtualDesktops);

        // If the count has changed from 0, the window may no longer be on all virtual
        // desktops.
        if (window->plasmaVirtualDesktops().count() > 0) {
            this->dataChanged(window, IsOnAllVirtualDesktops);
        }
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::plasmaVirtualDesktopLeft, q, [window, this] {
        this->dataChanged(window, VirtualDesktops);

        // If the count has changed to 0, the window is now on all virtual desktops.
        if (window->plasmaVirtualDesktops().count() == 0) {
            this->dataChanged(window, IsOnAllVirtualDesktops);
        }
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::geometryChanged, q, [window, this] {
        this->dataChanged(window, QVector<int>{Geometry, ScreenGeometry});
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::demandsAttentionChanged, q, [window, this] {
        this->dataChanged(window, IsDemandingAttention);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::skipTaskbarChanged, q, [window, this] {
        this->dataChanged(window, SkipTaskbar);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::applicationMenuChanged, q, [window, this] {
        this->dataChanged(window, QVector<int>{ApplicationMenuServiceName, ApplicationMenuObjectPath});
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::plasmaActivityEntered, q, [window, this] {
        this->dataChanged(window, Activities);
    });

    QObject::connect(window, &KWayland::Client::PlasmaWindow::plasmaActivityLeft, q, [window, this] {
        this->dataChanged(window, Activities);
    });
}

AppData WaylandTasksModel::Private::appData(KWayland::Client::PlasmaWindow *window)
{
    const auto &it = appDataCache.constFind(window);

    if (it != appDataCache.constEnd()) {
        return *it;
    }

    const AppData &data = appDataFromUrl(windowUrlFromMetadata(window->appId(), window->pid(), rulesConfig));

    appDataCache.insert(window, data);

    return data;
}

QIcon WaylandTasksModel::Private::icon(KWayland::Client::PlasmaWindow *window)
{
    const AppData &app = appData(window);

    if (!app.icon.isNull()) {
        return app.icon;
    }

    appDataCache[window].icon = window->icon();

    return window->icon();
}

QString WaylandTasksModel::Private::mimeType()
{
    // Use a unique format id to make this intentionally useless for
    // cross-process DND.
    return QStringLiteral("windowsystem/winid+") + uuid.toString();
}

QString WaylandTasksModel::Private::groupMimeType()
{
    // Use a unique format id to make this intentionally useless for
    // cross-process DND.
    return QStringLiteral("windowsystem/multiple-winids+") + uuid.toString();
}

void WaylandTasksModel::Private::dataChanged(KWayland::Client::PlasmaWindow *window, int role)
{
    QModelIndex idx = q->index(windows.indexOf(window));
    Q_EMIT q->dataChanged(idx, idx, QVector<int>{role});
}

void WaylandTasksModel::Private::dataChanged(KWayland::Client::PlasmaWindow *window, const QVector<int> &roles)
{
    QModelIndex idx = q->index(windows.indexOf(window));
    Q_EMIT q->dataChanged(idx, idx, roles);
}

WaylandTasksModel::WaylandTasksModel(QObject *parent)
    : AbstractWindowTasksModel(parent)
    , d(new Private(this))
{
    d->init();
}

WaylandTasksModel::~WaylandTasksModel() = default;

QVariant WaylandTasksModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid() || index.row() >= d->windows.count()) {
        return QVariant();
    }

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    if (role == Qt::DisplayRole) {
        return window->title();
    } else if (role == Qt::DecorationRole) {
        return d->icon(window);
    } else if (role == AppId) {
        const QString &id = d->appData(window).id;

        if (id.isEmpty()) {
            return window->appId();
        } else {
            return id;
        }
    } else if (role == AppName) {
        return d->appData(window).name;
    } else if (role == GenericName) {
        return d->appData(window).genericName;
    } else if (role == LauncherUrl || role == LauncherUrlWithoutIcon) {
        return d->appData(window).url;
    } else if (role == WinIdList) {
        return QVariantList() << window->uuid();
    } else if (role == MimeType) {
        return d->mimeType();
    } else if (role == MimeData) {
        return window->uuid();
    } else if (role == IsWindow) {
        return true;
    } else if (role == IsActive) {
        return window->isActive();
    } else if (role == IsClosable) {
        return window->isCloseable();
    } else if (role == IsMovable) {
        return window->isMovable();
    } else if (role == IsResizable) {
        return window->isResizable();
    } else if (role == IsMaximizable) {
        return window->isMaximizeable();
    } else if (role == IsMaximized) {
        return window->isMaximized();
    } else if (role == IsMinimizable) {
        return window->isMinimizeable();
    } else if (role == IsMinimized || role == IsHidden) {
        return window->isMinimized();
    } else if (role == IsKeepAbove) {
        return window->isKeepAbove();
    } else if (role == IsKeepBelow) {
        return window->isKeepBelow();
    } else if (role == IsFullScreenable) {
        return window->isFullscreenable();
    } else if (role == IsFullScreen) {
        return window->isFullscreen();
    } else if (role == IsShadeable) {
        return window->isShadeable();
    } else if (role == IsShaded) {
        return window->isShaded();
    } else if (role == IsVirtualDesktopsChangeable) {
        // FIXME Currently not implemented in KWayland.
        return true;
    } else if (role == VirtualDesktops) {
        return window->plasmaVirtualDesktops();
    } else if (role == IsOnAllVirtualDesktops) {
        return window->plasmaVirtualDesktops().isEmpty();
    } else if (role == Geometry) {
        return window->geometry();
    } else if (role == ScreenGeometry) {
        return screenGeometry(window->geometry().center());
    } else if (role == Activities) {
        return window->plasmaActivities();
    } else if (role == IsDemandingAttention) {
        return window->isDemandingAttention();
    } else if (role == SkipTaskbar) {
        return window->skipTaskbar() || d->appData(window).skipTaskbar;
    } else if (role == SkipPager) {
        // FIXME Implement.
    } else if (role == AppPid) {
        return window->pid();
    } else if (role == StackingOrder) {
        return d->windowManagement->stackingOrderUuids().indexOf(window->uuid());
    } else if (role == LastActivated) {
        if (d->lastActivated.contains(window)) {
            return d->lastActivated.value(window);
        }
    } else if (role == ApplicationMenuObjectPath) {
        return window->applicationMenuObjectPath();
    } else if (role == ApplicationMenuServiceName) {
        return window->applicationMenuServiceName();
    } else if (role == CanLaunchNewInstance) {
        return canLauchNewInstance(d->appData(window));
    }

    return QVariant();
}

int WaylandTasksModel::rowCount(const QModelIndex &parent) const
{
    return parent.isValid() ? 0 : d->windows.count();
}

QModelIndex WaylandTasksModel::index(int row, int column, const QModelIndex &parent) const
{
    return hasIndex(row, column, parent) ? createIndex(row, column, d->windows.at(row)) : QModelIndex();
}

void WaylandTasksModel::requestActivate(const QModelIndex &index)
{
    // FIXME Lacks transient handling of the XWindows version.

    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestActivate();
}

void WaylandTasksModel::requestNewInstance(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    runApp(d->appData(d->windows.at(index.row())));
}

void WaylandTasksModel::requestOpenUrls(const QModelIndex &index, const QList<QUrl> &urls)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count() || urls.isEmpty()) {
        return;
    }

    runApp(d->appData(d->windows.at(index.row())), urls);
}

void WaylandTasksModel::requestClose(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestClose();
}

void WaylandTasksModel::requestMove(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    window->requestActivate();
    window->requestMove();
}

void WaylandTasksModel::requestResize(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    window->requestActivate();
    window->requestResize();
}

void WaylandTasksModel::requestToggleMinimized(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestToggleMinimized();
}

void WaylandTasksModel::requestToggleMaximized(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    window->requestActivate();
    window->requestToggleMaximized();
}

void WaylandTasksModel::requestToggleKeepAbove(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestToggleKeepAbove();
}

void WaylandTasksModel::requestToggleKeepBelow(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestToggleKeepBelow();
}

void WaylandTasksModel::requestToggleFullScreen(const QModelIndex &index)
{
    Q_UNUSED(index)

    // FIXME Implement.
}

void WaylandTasksModel::requestToggleShaded(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestToggleShaded();
}

void WaylandTasksModel::requestVirtualDesktops(const QModelIndex &index, const QVariantList &desktops)
{
    // FIXME TODO: Lacks the "if we've requested the current desktop, force-activate
    // the window" logic from X11 version. This behavior should be in KWin rather than
    // libtm however.

    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    if (desktops.isEmpty()) {
        const QStringList virtualDesktops = window->plasmaVirtualDesktops();
        for (const QString &desktop : virtualDesktops) {
            window->requestLeaveVirtualDesktop(desktop);
        }
    } else {
        const QStringList &now = window->plasmaVirtualDesktops();
        QStringList next;

        for (const QVariant &desktop : desktops) {
            const QString &desktopId = desktop.toString();

            if (!desktopId.isEmpty()) {
                next << desktopId;

                if (!now.contains(desktopId)) {
                    window->requestEnterVirtualDesktop(desktopId);
                }
            }
        }

        for (const QString &desktop : now) {
            if (!next.contains(desktop)) {
                window->requestLeaveVirtualDesktop(desktop);
            }
        }
    }
}

void WaylandTasksModel::requestNewVirtualDesktop(const QModelIndex &index)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    d->windows.at(index.row())->requestEnterNewVirtualDesktop();
}

void WaylandTasksModel::requestActivities(const QModelIndex &index, const QStringList &activities)
{
    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    auto *const window = d->windows.at(index.row());
    const auto newActivities = QSet(activities.begin(), activities.end());
    const auto plasmaActivities = window->plasmaActivities();
    const auto oldActivities = QSet(plasmaActivities.begin(), plasmaActivities.end());

    const auto activitiesToAdd = newActivities - oldActivities;
    for (const auto &activity : activitiesToAdd) {
        window->requestEnterActivity(activity);
    }

    const auto activitiesToRemove = oldActivities - newActivities;
    for (const auto &activity : activitiesToRemove) {
        window->requestLeaveActivity(activity);
    }
}

void WaylandTasksModel::requestPublishDelegateGeometry(const QModelIndex &index, const QRect &geometry, QObject *delegate)
{
    /*
    FIXME: This introduces the dependency on Qt::Quick. I might prefer
    reversing this and publishing the window pointer through the model,
    then calling PlasmaWindow::setMinimizeGeometry in the applet backend,
    rather than hand delegate items into the lib, keeping the lib more UI-
    agnostic.
    */

    Q_UNUSED(geometry)

    if (!index.isValid() || index.model() != this || index.row() < 0 || index.row() >= d->windows.count()) {
        return;
    }

    const QQuickItem *item = qobject_cast<const QQuickItem *>(delegate);

    if (!item || !item->parentItem() || !item->window()) {
        return;
    }

    QWindow *itemWindow = item->window();

    if (!itemWindow) {
        return;
    }

    using namespace KWayland::Client;
    Surface *surface = Surface::fromWindow(itemWindow);

    if (!surface) {
        return;
    }

    QRect rect(item->x(), item->y(), item->width(), item->height());
    rect.moveTopLeft(item->parentItem()->mapToScene(rect.topLeft()).toPoint());

    KWayland::Client::PlasmaWindow *window = d->windows.at(index.row());

    window->setMinimizedGeometry(surface, rect);
}

QUuid WaylandTasksModel::winIdFromMimeData(const QMimeData *mimeData, bool *ok)
{
    Q_ASSERT(mimeData);

    if (ok) {
        *ok = false;
    }

    if (!mimeData->hasFormat(Private::mimeType())) {
        return 0;
    }

    QUuid id(mimeData->data(Private::mimeType()));
    *ok = !id.isNull();

    return id;
}

QList<QUuid> WaylandTasksModel::winIdsFromMimeData(const QMimeData *mimeData, bool *ok)
{
    Q_ASSERT(mimeData);
    QList<QUuid> ids;

    if (ok) {
        *ok = false;
    }

    if (!mimeData->hasFormat(Private::groupMimeType())) {
        // Try to extract single window id.
        bool singularOk;
        QUuid id = winIdFromMimeData(mimeData, &singularOk);

        if (ok) {
            *ok = singularOk;
        }

        if (singularOk) {
            ids << id;
        }

        return ids;
    }

    // FIXME: Extracting multiple winids is still unimplemented;
    // TaskGroupingProxy::data(..., ::MimeData) can't produce
    // a payload with them anyways.

    return ids;
}

}