Add a parent_window event to Plasma Window interface

Summary:
This change adds a parent_window event to Plasma Window. From server
side it's possible to specify that a window is a transient for another
window - that is it has a parent window.

On client side this is exposed respectively with a new change signal.

Reviewers: #plasma_on_wayland, hein

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D1779

src/wayland/autotests/client/test_wayland_windowmanagement.cpp

@@ -64,6 +64,7 @@ private Q_SLOTS:
     void testShowingDesktop();
     void testRequestShowingDesktop_data();
     void testRequestShowingDesktop();
+    void testParentWindow();
 
     void cleanup();
 
@@ -470,5 +471,43 @@ void TestWindowManagement::testRequestShowingDesktop()
     QTEST(requestSpy.first().first().value<PlasmaWindowManagementInterface::ShowingDesktopState>(), "expectedValue");
 }
 
+void TestWindowManagement::testParentWindow()
+{
+    using namespace KWayland::Client;
+    // this test verifies the functionality of ParentWindows
+    QCOMPARE(m_windowManagement->windows().count(), 1);
+    auto parentWindow = m_windowManagement->windows().first();
+    QVERIFY(parentWindow);
+    QVERIFY(parentWindow->parentWindow().isNull());
+
+    // now let's create a second window
+    QSignalSpy windowAddedSpy(m_windowManagement, &PlasmaWindowManagement::windowCreated);
+    QVERIFY(windowAddedSpy.isValid());
+    auto serverTransient = m_windowManagementInterface->createWindow(this);
+    serverTransient->setParentWindow(m_windowInterface);
+    QVERIFY(windowAddedSpy.wait());
+    auto transient = windowAddedSpy.first().first().value<PlasmaWindow*>();
+    QCOMPARE(transient->parentWindow().data(), parentWindow);
+
+    // let's unset the parent
+    QSignalSpy parentWindowChangedSpy(transient, &PlasmaWindow::parentWindowChanged);
+    QVERIFY(parentWindowChangedSpy.isValid());
+    serverTransient->setParentWindow(nullptr);
+    QVERIFY(parentWindowChangedSpy.wait());
+    QVERIFY(transient->parentWindow().isNull());
+
+    // and set it again
+    serverTransient->setParentWindow(m_windowInterface);
+    QVERIFY(parentWindowChangedSpy.wait());
+    QCOMPARE(transient->parentWindow().data(), parentWindow);
+
+    // now let's try to unmap the parent
+    m_windowInterface->unmap();
+    m_window = nullptr;
+    m_windowInterface = nullptr;
+    QVERIFY(parentWindowChangedSpy.wait());
+    QVERIFY(transient->parentWindow().isNull());
+}
+
 QTEST_GUILESS_MAIN(TestWindowManagement)
 #include "test_wayland_windowmanagement.moc"

src/wayland/plasmawindowmanagement_interface.cpp

@@ -73,6 +73,8 @@ public:
     void setVirtualDesktop(quint32 desktop);
     void unmap();
     void setState(org_kde_plasma_window_management_state flag, bool set);
+    void setParentWindow(PlasmaWindowInterface *parent);
+    wl_resource *resourceForParent(PlasmaWindowInterface *parent, wl_resource *child) const;
 
     QVector<wl_resource*> resources;
     quint32 windowId = 0;
@@ -80,6 +82,8 @@ public:
     PlasmaWindowManagementInterface *wm;
 
     bool unmapped = false;
+    PlasmaWindowInterface *parentWindow = nullptr;
+    QMetaObject::Connection parentWindowDestroyConnection;
 
 private:
     static void unbind(wl_resource *resource);
@@ -105,7 +109,7 @@ private:
     static const struct org_kde_plasma_window_interface s_interface;
 };
 
-const quint32 PlasmaWindowManagementInterface::Private::s_version = 4;
+const quint32 PlasmaWindowManagementInterface::Private::s_version = 5;
 
 PlasmaWindowManagementInterface::Private::Private(PlasmaWindowManagementInterface *q, Display *d)
     : Global::Private(d, &org_kde_plasma_window_management_interface, s_version)
@@ -321,6 +325,8 @@ void PlasmaWindowInterface::Private::createResource(wl_resource *parent, uint32_
     org_kde_plasma_window_send_state_changed(resource, m_state);
     org_kde_plasma_window_send_themed_icon_name_changed(resource, m_themedIconName.toUtf8().constData());
 
+    org_kde_plasma_window_send_parent_window(resource, resourceForParent(parentWindow, resource));
+
     if (unmapped) {
         org_kde_plasma_window_send_unmapped(resource);
     }
@@ -406,6 +412,46 @@ void PlasmaWindowInterface::Private::setState(org_kde_plasma_window_management_s
     }
 }
 
+wl_resource *PlasmaWindowInterface::Private::resourceForParent(PlasmaWindowInterface *parent, wl_resource *child) const
+{
+    if (!parent) {
+        return nullptr;
+    }
+    auto it = std::find_if(parent->d->resources.begin(), parent->d->resources.end(),
+        [child] (wl_resource *parentResource) {
+            return wl_resource_get_client(child) == wl_resource_get_client(parentResource);
+        }
+    );
+    if (it != parent->d->resources.end()) {
+        return *it;
+    }
+    return nullptr;
+}
+
+void PlasmaWindowInterface::Private::setParentWindow(PlasmaWindowInterface *window)
+{
+    if (parentWindow == window) {
+        return;
+    }
+    QObject::disconnect(parentWindowDestroyConnection);
+    parentWindowDestroyConnection = QMetaObject::Connection();
+    parentWindow = window;
+    if (parentWindow) {
+        parentWindowDestroyConnection = QObject::connect(window, &QObject::destroyed, q,
+            [this] {
+                parentWindow = nullptr;
+                parentWindowDestroyConnection = QMetaObject::Connection();
+                for (auto it = resources.constBegin(); it != resources.constEnd(); ++it) {
+                    org_kde_plasma_window_send_parent_window(*it, nullptr);
+                }
+            }
+        );
+    }
+    for (auto it = resources.constBegin(); it != resources.constEnd(); ++it) {
+        org_kde_plasma_window_send_parent_window(*it, resourceForParent(window, *it));
+    }
+}
+
 void PlasmaWindowInterface::Private::closeCallback(wl_client *client, wl_resource *resource)
 {
     Q_UNUSED(client)
@@ -658,5 +704,10 @@ void PlasmaWindowInterface::setVirtualDesktopChangeable(bool set)
     d->setState(ORG_KDE_PLASMA_WINDOW_MANAGEMENT_STATE_VIRTUAL_DESKTOP_CHANGEABLE, set);
 }
 
+void PlasmaWindowInterface::setParentWindow(PlasmaWindowInterface *parentWindow)
+{
+    d->setParentWindow(parentWindow);
+}
+
 }
 }

src/wayland/plasmawindowmanagement_interface.h

@@ -139,6 +139,14 @@ public:
      */
     QHash<SurfaceInterface*, QRect> minimizedGeometries() const;
 
+    /**
+     * Sets this PlasmaWindowInterface as a transient window to @p parentWindow.
+     * If @p parentWindow is @c nullptr, the PlasmaWindowInterface is a toplevel
+     * window and does not have a parent window.
+     * @since 5.24
+     **/
+    void setParentWindow(PlasmaWindowInterface *parentWindow);
+
 Q_SIGNALS:
     void closeRequested();
     /**