scripting: Introduce VirtualDesktopModel

This can be useful for QML scripts that deal with virtual desktops.

The virtual desktop model keeps a copy of virtual desktop objects to
avoid hitting asserts in QAbstractItemModel (it has some asserts to
ensure that indices passed to beginInsertRows() or beginRemoveRows()
make sense).

src/CMakeLists.txt

@@ -101,6 +101,7 @@ set(kwin_SRCS
     screens.cpp
     scripting/v2/clientmodel.cpp
     scripting/v3/clientmodel.cpp
+    scripting/v3/virtualdesktopmodel.cpp
     scripting/dbuscall.cpp
     scripting/screenedgeitem.cpp
     scripting/scriptedeffect.cpp

src/scripting/scripting.cpp

@@ -20,6 +20,7 @@
 
 #include "v2/clientmodel.h"
 #include "v3/clientmodel.h"
+#include "v3/virtualdesktopmodel.h"
 
 #include "input.h"
 #include "options.h"
@@ -649,6 +650,7 @@ void KWin::Scripting::init()
     qmlRegisterType<ScreenEdgeItem>("org.kde.kwin", 3, 0, "ScreenEdgeItem");
     qmlRegisterType<ScriptingModels::V3::ClientModel>("org.kde.kwin", 3, 0, "ClientModel");
     qmlRegisterType<ScriptingModels::V3::ClientFilterModel>("org.kde.kwin", 3, 0, "ClientFilterModel");
+    qmlRegisterType<ScriptingModels::V3::VirtualDesktopModel>("org.kde.kwin", 3, 0, "VirtualDesktopModel");
 
     qmlRegisterSingletonType<QtScriptWorkspaceWrapper>("org.kde.kwin", 3, 0, "Workspace", [](QQmlEngine *qmlEngine, QJSEngine *jsEngine) {
         Q_UNUSED(qmlEngine)

src/scripting/v3/virtualdesktopmodel.cpp

@@ -0,0 +1,91 @@
+/*
+    SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#include "virtualdesktopmodel.h"
+#include "virtualdesktops.h"
+
+namespace KWin::ScriptingModels::V3
+{
+
+VirtualDesktopModel::VirtualDesktopModel(QObject *parent)
+    : QAbstractListModel(parent)
+{
+    VirtualDesktopManager *manager = VirtualDesktopManager::self();
+
+    connect(manager, &VirtualDesktopManager::desktopCreated,
+            this, &VirtualDesktopModel::handleVirtualDesktopAdded);
+    connect(manager, &VirtualDesktopManager::desktopRemoved,
+            this, &VirtualDesktopModel::handleVirtualDesktopRemoved);
+
+    m_virtualDesktops = manager->desktops();
+}
+
+void VirtualDesktopModel::create(uint position, const QString &name)
+{
+    VirtualDesktopManager::self()->createVirtualDesktop(position, name);
+}
+
+void VirtualDesktopModel::remove(uint position)
+{
+    if (position < m_virtualDesktops.count()) {
+        VirtualDesktopManager::self()->removeVirtualDesktop(m_virtualDesktops[position]);
+    }
+}
+
+void VirtualDesktopModel::handleVirtualDesktopAdded(VirtualDesktop *desktop)
+{
+    const int position = desktop->x11DesktopNumber() - 1;
+    beginInsertRows(QModelIndex(), position, position);
+    m_virtualDesktops.insert(position, desktop);
+    endInsertRows();
+}
+
+void VirtualDesktopModel::handleVirtualDesktopRemoved(VirtualDesktop *desktop)
+{
+    const int index = m_virtualDesktops.indexOf(desktop);
+    Q_ASSERT(index != -1);
+
+    beginRemoveRows(QModelIndex(), index, index);
+    m_virtualDesktops.removeAt(index);
+    endRemoveRows();
+}
+
+QHash<int, QByteArray> VirtualDesktopModel::roleNames() const
+{
+    QHash<int, QByteArray> roleNames = QAbstractListModel::roleNames();
+    roleNames.insert(DesktopRole, QByteArrayLiteral("desktop"));
+    return roleNames;
+}
+
+VirtualDesktop *VirtualDesktopModel::desktopFromIndex(const QModelIndex &index) const
+{
+    if (!index.isValid() || index.row() < 0 || index.row() >= m_virtualDesktops.count()) {
+        return nullptr;
+    }
+    return m_virtualDesktops[index.row()];
+}
+
+QVariant VirtualDesktopModel::data(const QModelIndex &index, int role) const
+{
+    VirtualDesktop *desktop = desktopFromIndex(index);
+    if (!desktop) {
+        return QVariant();
+    }
+    switch (role) {
+    case Qt::DisplayRole:
+    case DesktopRole:
+        return QVariant::fromValue(desktop);
+    default:
+        return QVariant();
+    }
+}
+
+int VirtualDesktopModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : m_virtualDesktops.count();
+}
+
+} // namespace KWin::ScriptingModels::V3

src/scripting/v3/virtualdesktopmodel.h

@@ -0,0 +1,50 @@
+/*
+    SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#pragma once
+
+#include <QAbstractListModel>
+
+namespace KWin
+{
+class VirtualDesktop;
+
+namespace ScriptingModels::V3
+{
+
+/**
+ * The VirtualDesktopModel class provides a data model for the virtual desktops.
+ */
+class VirtualDesktopModel : public QAbstractListModel
+{
+    Q_OBJECT
+
+public:
+    enum Role {
+        DesktopRole = Qt::UserRole + 1,
+    };
+
+    explicit VirtualDesktopModel(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;
+
+public Q_SLOTS:
+    void create(uint position, const QString &name = QString());
+    void remove(uint position);
+
+private:
+    KWin::VirtualDesktop *desktopFromIndex(const QModelIndex &index) const;
+
+    void handleVirtualDesktopAdded(KWin::VirtualDesktop *desktop);
+    void handleVirtualDesktopRemoved(KWin::VirtualDesktop *desktop);
+
+    QVector<KWin::VirtualDesktop *> m_virtualDesktops;
+};
+
+} // namespace ScriptingModels::V3
+} // namespace KWin

src/virtualdesktops.cpp

@@ -483,15 +483,19 @@ VirtualDesktop *VirtualDesktopManager::createVirtualDesktop(uint position, const
 }
 
 void VirtualDesktopManager::removeVirtualDesktop(const QString &id)
+{
+    auto desktop = desktopForId(id);
+    if (desktop) {
+        removeVirtualDesktop(desktop);
+    }
+}
+
+void VirtualDesktopManager::removeVirtualDesktop(VirtualDesktop *desktop)
 {
     //don't end up without any desktop
     if (m_desktops.count() == 1) {
         return;
     }
-    auto desktop = desktopForId(id);
-    if (!desktop) {
-        return;
-    }
 
     const uint oldCurrent = m_current->x11DesktopNumber();
     const uint i = desktop->x11DesktopNumber() - 1;

src/virtualdesktops.h

@@ -285,6 +285,7 @@ public:
      * @param id the string id of the desktop to remove
      */
     void removeVirtualDesktop(const QString &id);
+    void removeVirtualDesktop(VirtualDesktop *desktop);
 
     /**
      * Updates the net root info for new number of desktops