taskswitcher: Sort tasks by last activation

Fixes https://invent.kde.org/plasma/plasma-mobile/-/issues/343

This restores the sorting of tasks by their last activation. The task model now becomes a singleton and retains state even while the effect is not active, while the filter/sort proxy model is still initialized at task switcher load.

CMakeLists.txt

@@ -72,6 +72,7 @@ find_package(KF6 ${KF6_MIN_VERSION} REQUIRED COMPONENTS
 
 find_package(Plasma CONFIG REQUIRED)
 find_package(PlasmaQuick CONFIG REQUIRED)
+find_package(PlasmaActivities CONFIG REQUIRED)
 find_package(KF6Screen CONFIG REQUIRED)
 find_package(KWayland CONFIG REQUIRED)
 

kwin/mobiletaskswitcher/CMakeLists.txt

@@ -6,6 +6,8 @@ target_sources(mobiletaskswitcher PRIVATE
     main.cpp
     mobiletaskswitchereffect.cpp
     effecttouchborder.cpp
+    taskfiltermodel.cpp
+    taskmodel.cpp
 )
 
 target_link_libraries(mobiletaskswitcher
@@ -19,6 +21,7 @@ target_link_libraries(mobiletaskswitcher
     Qt::Core
 
     KWin::kwin
+    Plasma::Activities
 )
 
 # install(TARGETS kwin4_effect_taskswitcher DESTINATION ${PLUGIN_INSTALL_DIR}/kwin/effects/plugins)

kwin/mobiletaskswitcher/mobiletaskswitchereffect.cpp

@@ -193,13 +193,18 @@ void MobileTaskSwitcherState::processTouchPositionChanged(qreal primaryDelta, qr
 MobileTaskSwitcherEffect::MobileTaskSwitcherEffect()
     : m_effectState{new EffectTouchBorderState(this)}
     , m_taskSwitcherState{new MobileTaskSwitcherState(m_effectState)}
+    , m_taskModel{new TaskModel{this}}
     , m_border{new EffectTouchBorder{m_effectState}}
     , m_toggleAction{std::make_unique<QAction>()}
     , m_shutdownTimer{new QTimer{this}}
 {
     const char *uri = "org.kde.private.mobileshell.taskswitcher";
+    qmlRegisterType<TaskFilterModel>(uri, 1, 0, "TaskFilterModel");
+    qmlRegisterSingletonType<TaskModel>(uri, 1, 0, "TaskModel", [this](QQmlEngine *, QJSEngine *) -> QObject * {
+        return m_taskModel;
+    });
     qmlRegisterSingletonType<MobileTaskSwitcherState>(uri, 1, 0, "TaskSwitcherState", [this](QQmlEngine *, QJSEngine *) -> QObject * {
-        return this->m_taskSwitcherState;
+        return m_taskSwitcherState;
     });
 
     connect(m_border, &EffectTouchBorder::touchPositionChanged, m_taskSwitcherState, &MobileTaskSwitcherState::processTouchPositionChanged);

kwin/mobiletaskswitcher/mobiletaskswitchereffect.h

@@ -21,6 +21,8 @@
 #include <KLocalizedString>
 
 #include "effecttouchborder.h"
+#include "taskfiltermodel.h"
+#include "taskmodel.h"
 
 namespace KWin
 {
@@ -184,6 +186,7 @@ private:
 
     EffectTouchBorderState *const m_effectState;
     MobileTaskSwitcherState *const m_taskSwitcherState;
+    TaskModel *const m_taskModel;
     EffectTouchBorder *const m_border;
     QList<int> m_borderActivate = {ElectricBorder::ElectricBottom};
 

kwin/mobiletaskswitcher/qml/TaskSwitcher.qml

@@ -39,33 +39,9 @@ FocusScope {
         stateClass: TaskSwitcherData.TaskSwitcherState
     }
 
-    KWinComponents.WindowModel {
-        id: stackModel
-    }
-
-    KWinComponents.VirtualDesktopModel {
-        id: desktopModel
-    }
-
-    property var baseTasksModel: KWinComponents.WindowFilterModel {
-        activity: KWinComponents.Workspace.currentActivity
-        desktop: KWinComponents.Workspace.currentDesktop
+    property var tasksModel: TaskSwitcherData.TaskFilterModel {
         screenName: root.targetScreen.name
-        windowModel: stackModel
-        minimizedWindows: true
-        windowType: ~KWinComponents.WindowFilterModel.Dock &
-                    ~KWinComponents.WindowFilterModel.Desktop &
-                    ~KWinComponents.WindowFilterModel.Notification &
-                    ~KWinComponents.WindowFilterModel.CriticalNotification
-    }
-
-    property var tasksModel: KSortFilterProxyModel {
-        sourceModel: baseTasksModel
-        filterRoleName: 'window'
-        filterRowCallback: function(source_row, source_parent) {
-            const window = sourceModel.data(sourceModel.index(source_row, 0, source_parent), Qt.DisplayRole);
-            return !window.skipSwitcher;
-        }
+        windowModel: TaskSwitcherData.TaskModel
     }
 
     readonly property int tasksCount: taskList.count

kwin/mobiletaskswitcher/taskfiltermodel.cpp

@@ -0,0 +1,139 @@
+// SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "taskfiltermodel.h"
+
+// KWin
+#include <activities.h>
+#include <core/output.h>
+#include <core/outputbackend.h>
+#include <virtualdesktops.h>
+#include <workspace.h>
+
+namespace KWin
+{
+
+TaskFilterModel::TaskFilterModel(QObject *parent)
+    : QSortFilterProxyModel(parent)
+{
+    setSortRole(TaskModel::LastActivatedRole);
+
+    // Don't auto-sort, because this model is loaded at runtime during the task switcher
+    // -> We don't want to re-sort while the task switcher is open
+    setDynamicSortFilter(false);
+}
+
+TaskModel *TaskFilterModel::windowModel() const
+{
+    return m_taskModel;
+}
+
+void TaskFilterModel::setWindowModel(TaskModel *taskModel)
+{
+    if (taskModel == m_taskModel) {
+        return;
+    }
+    m_taskModel = taskModel;
+    setSourceModel(m_taskModel);
+    Q_EMIT windowModelChanged();
+
+    // Sort after source model is set
+    sort(0);
+}
+
+QString TaskFilterModel::screenName() const
+{
+    return m_output ? m_output->name() : QString();
+}
+
+void TaskFilterModel::setScreenName(const QString &screen)
+{
+    Output *output = kwinApp()->outputBackend()->findOutput(screen);
+    if (m_output != output) {
+        m_output = output;
+        Q_EMIT screenNameChanged();
+        invalidateFilter();
+    }
+}
+
+bool TaskFilterModel::filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const
+{
+    if (!m_taskModel) {
+        return false;
+    }
+    const QModelIndex index = m_taskModel->index(sourceRow, 0, sourceParent);
+    if (!index.isValid()) {
+        return false;
+    }
+    const QVariant data = index.data();
+    if (!data.isValid()) {
+        // an invalid QVariant is valid data
+        return true;
+    }
+
+    Window *window = qvariant_cast<Window *>(data);
+    if (!window || !window->isClient()) {
+        return false;
+    }
+
+    // Filter by same activity
+    auto activity = Workspace::self()->activities()->current();
+    if (!window->isOnActivity(activity)) {
+        return false;
+    }
+
+    // Filter by same desktop
+    auto desktop = VirtualDesktopManager::self()->currentDesktop();
+    if (!window->isOnDesktop(desktop)) {
+        return false;
+    }
+
+    // Filter by same screen
+    if (window->output() != m_output) {
+        return false;
+    }
+
+    if (window->isDock()) {
+        return false;
+    }
+    if (window->isDesktop()) {
+        return false;
+    }
+    if (window->isNotification()) {
+        return false;
+    }
+    if (window->isCriticalNotification()) {
+        return false;
+    }
+    if (window->skipSwitcher()) {
+        return false;
+    }
+
+    return true;
+}
+
+bool TaskFilterModel::lessThan(const QModelIndex &left, const QModelIndex &right) const
+{
+    qint64 leftLastActivated = qvariant_cast<qint64>(left.data(TaskModel::LastActivatedRole));
+    qint64 rightLastActivated = qvariant_cast<qint64>(right.data(TaskModel::LastActivatedRole));
+
+    // Sort order: oldest -> newest
+    // - For ties: alphabetically
+
+    if (leftLastActivated != rightLastActivated) {
+        return leftLastActivated > rightLastActivated;
+    } else {
+        // If leftLastActivated == rightLastActivated, sort alphabetically by window title
+        Window *leftWindow = qvariant_cast<Window *>(left.data(TaskModel::WindowRole));
+        Window *rightWindow = qvariant_cast<Window *>(right.data(TaskModel::WindowRole));
+
+        if (!leftWindow || !rightWindow) {
+            return true;
+        }
+
+        return leftWindow->caption() < rightWindow->caption();
+    }
+}
+
+} // namespace KWin

kwin/mobiletaskswitcher/taskfiltermodel.h

@@ -0,0 +1,47 @@
+// SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "taskmodel.h"
+
+#include <window.h>
+
+#include <QAbstractListModel>
+#include <QHash>
+#include <QSortFilterProxyModel>
+#include <QVariant>
+
+namespace KWin
+{
+
+class TaskFilterModel : public QSortFilterProxyModel
+{
+    Q_OBJECT
+    Q_PROPERTY(TaskModel *windowModel READ windowModel WRITE setWindowModel NOTIFY windowModelChanged)
+    Q_PROPERTY(QString screenName READ screenName WRITE setScreenName NOTIFY screenNameChanged)
+
+public:
+    explicit TaskFilterModel(QObject *parent = nullptr);
+
+    TaskModel *windowModel() const;
+    void setWindowModel(TaskModel *taskModel);
+
+    QString screenName() const;
+    void setScreenName(const QString &screenName);
+
+protected:
+    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
+    bool lessThan(const QModelIndex &left, const QModelIndex &right) const override;
+
+Q_SIGNALS:
+    void screenNameChanged();
+    void windowModelChanged();
+
+private:
+    TaskModel *m_taskModel = nullptr;
+    QPointer<Output> m_output;
+};
+
+} // namespace KWin

kwin/mobiletaskswitcher/taskmodel.cpp

@@ -0,0 +1,140 @@
+// SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "taskmodel.h"
+
+// KWin
+#include <core/output.h>
+#include <virtualdesktops.h>
+#include <workspace.h>
+
+namespace KWin
+{
+
+TaskModel::TaskModel(QObject *parent)
+    : QAbstractListModel(parent)
+{
+    connect(workspace(), &Workspace::windowAdded, this, &TaskModel::handleWindowAdded);
+    connect(workspace(), &Workspace::windowRemoved, this, &TaskModel::handleWindowRemoved);
+    connect(workspace(), &Workspace::windowActivated, this, &TaskModel::handleActiveWindowChanged);
+
+    auto windows = workspace()->windows();
+    const qint64 currentTime = QDateTime::currentMSecsSinceEpoch();
+
+    for (Window *window : std::as_const(windows)) {
+        m_windows.push_back({window, currentTime});
+        setupWindowConnections(window);
+    }
+}
+
+void TaskModel::markRoleChanged(Window *window, int role)
+{
+    int windowIndex = -1;
+    for (int i = 0; i < m_windows.size(); ++i) {
+        if (m_windows[i].first == window) {
+            windowIndex = i;
+            break;
+        }
+    }
+    const QModelIndex row = index(windowIndex, 0);
+    Q_EMIT dataChanged(row, row, {role});
+}
+
+void TaskModel::setupWindowConnections(Window *window)
+{
+    connect(window, &Window::desktopsChanged, this, [this, window]() {
+        markRoleChanged(window, DesktopRole);
+    });
+    connect(window, &Window::outputChanged, this, [this, window]() {
+        markRoleChanged(window, OutputRole);
+    });
+    connect(window, &Window::activitiesChanged, this, [this, window]() {
+        markRoleChanged(window, ActivityRole);
+    });
+}
+
+void TaskModel::handleWindowAdded(Window *window)
+{
+    beginInsertRows(QModelIndex(), m_windows.count(), m_windows.count());
+    const qint64 currentTime = QDateTime::currentMSecsSinceEpoch();
+    m_windows.append({window, currentTime});
+    endInsertRows();
+
+    setupWindowConnections(window);
+}
+
+void TaskModel::handleWindowRemoved(Window *window)
+{
+    int index = -1;
+    for (int i = 0; i < m_windows.size(); ++i) {
+        if (m_windows[i].first == window) {
+            index = i;
+            break;
+        }
+    }
+    Q_ASSERT(index != -1);
+
+    beginRemoveRows(QModelIndex(), index, index);
+    m_windows.removeAt(index);
+    endRemoveRows();
+}
+
+QHash<int, QByteArray> TaskModel::roleNames() const
+{
+    return {
+        {Qt::DisplayRole, QByteArrayLiteral("display")},
+        {WindowRole, QByteArrayLiteral("window")},
+        {OutputRole, QByteArrayLiteral("output")},
+        {DesktopRole, QByteArrayLiteral("desktop")},
+        {ActivityRole, QByteArrayLiteral("activity")},
+    };
+}
+
+QVariant TaskModel::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid() || index.row() < 0 || index.row() >= m_windows.count()) {
+        return QVariant();
+    }
+
+    Window *window = m_windows[index.row()].first;
+    qint64 lastActivated = m_windows[index.row()].second;
+    switch (role) {
+    case Qt::DisplayRole:
+    case WindowRole:
+        return QVariant::fromValue(window);
+    case OutputRole:
+        return QVariant::fromValue(window->output());
+    case DesktopRole:
+        return QVariant::fromValue(window->desktops());
+    case ActivityRole:
+        return window->activities();
+    case LastActivatedRole:
+        return lastActivated;
+    default:
+        return QVariant();
+    }
+}
+
+int TaskModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : m_windows.count();
+}
+
+void TaskModel::handleActiveWindowChanged()
+{
+    Window *window = workspace()->activeWindow();
+    if (!window) {
+        return;
+    }
+
+    const qint64 currentTime = QDateTime::currentMSecsSinceEpoch();
+    for (int i = 0; i < m_windows.size(); ++i) {
+        if (m_windows[i].first == window) {
+            m_windows[i] = {window, currentTime};
+            Q_EMIT dataChanged(index(i, 0), index(i, 0), {TaskModel::LastActivatedRole});
+        }
+    }
+}
+
+} // namespace KWin

kwin/mobiletaskswitcher/taskmodel.h

@@ -0,0 +1,43 @@
+// SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+// SPDX-FileCopyrightText: 2024 Devin Lin <devin@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <window.h>
+
+#include <QAbstractListModel>
+#include <QHash>
+#include <QSortFilterProxyModel>
+#include <QVariant>
+
+namespace KWin
+{
+
+class TaskModel : public QAbstractListModel
+{
+    Q_OBJECT
+
+public:
+    enum Roles { WindowRole = Qt::UserRole + 1, OutputRole, DesktopRole, ActivityRole, LastActivatedRole };
+
+    explicit TaskModel(QObject *parent = nullptr);
+
+    QHash<int, QByteArray> roleNames() const override;
+    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+
+private:
+    void markRoleChanged(Window *window, int role);
+
+    void handleWindowAdded(Window *window);
+    void handleWindowRemoved(Window *window);
+    void setupWindowConnections(Window *window);
+
+    void handleActiveWindowChanged();
+
+    // qint64 - Last activated timestamp
+    QList<std::pair<Window *, qint64>> m_windows;
+};
+
+}; // namespace KWin