x11: Hard-code 0 default screen

The screen number matters only on multi-head setups.

autotests/integration/xwaylandserver_crash_test.cpp

@@ -129,7 +129,6 @@ void XwaylandServerCrashTest::testCrash()
     QCOMPARE(kwinApp()->x11Connection(), nullptr);
     QCOMPARE(kwinApp()->x11DefaultScreen(), nullptr);
     QCOMPARE(kwinApp()->x11RootWindow(), XCB_WINDOW_NONE);
-    QCOMPARE(kwinApp()->x11ScreenNumber(), -1);
 
     // Render a frame to ensure that the compositor doesn't crash.
     Compositor::self()->scene()->addRepaintFull();

autotests/test_virtual_desktops.cpp

@@ -17,8 +17,6 @@
 namespace KWin
 {
 
-int screen_number = 0;
-
 InputRedirection *InputRedirection::s_self = nullptr;
 
 void InputRedirection::registerShortcut(const QKeySequence &shortcut, QAction *action)
@@ -101,7 +99,6 @@ private:
 void TestVirtualDesktops::init()
 {
     VirtualDesktopManager::create();
-    screen_number = 0;
 }
 
 void TestVirtualDesktops::cleanup()

src/composite.cpp

@@ -331,9 +331,7 @@ void Compositor::initializeX11()
     }
 
     if (!m_selectionOwner) {
-        char selection_name[100];
-        sprintf(selection_name, "_NET_WM_CM_S%d", Application::x11ScreenNumber());
-        m_selectionOwner = std::make_unique<CompositorSelectionOwner>(selection_name);
+        m_selectionOwner = std::make_unique<CompositorSelectionOwner>("_NET_WM_CM_S0");
         connect(m_selectionOwner.get(), &CompositorSelectionOwner::lostOwnership, this, &Compositor::stop);
     }
     if (!m_selectionOwner->owning()) {

src/main.cpp

@@ -60,23 +60,9 @@ namespace KWin
 {
 
 Options *options;
-
 Atoms *atoms;
-
-int screen_number = -1;
-
 int Application::crashes = 0;
 
-void Application::setX11ScreenNumber(int screenNumber)
-{
-    screen_number = screenNumber;
-}
-
-int Application::x11ScreenNumber()
-{
-    return screen_number;
-}
-
 Application::Application(Application::OperationMode mode, int &argc, char **argv)
     : QApplication(argc, argv)
     , m_eventFilter(new XcbEventFilter())

src/main.h

@@ -58,7 +58,6 @@ class KWIN_EXPORT Application : public QApplication
     Q_PROPERTY(quint32 x11Time READ x11Time WRITE setX11Time)
     Q_PROPERTY(quint32 x11RootWindow READ x11RootWindow CONSTANT)
     Q_PROPERTY(void *x11Connection READ x11Connection NOTIFY x11ConnectionChanged)
-    Q_PROPERTY(int x11ScreenNumber READ x11ScreenNumber CONSTANT)
     Q_PROPERTY(KSharedConfigPtr config READ config WRITE setConfig)
     Q_PROPERTY(KSharedConfigPtr kxkbConfig READ kxkbConfig WRITE setKxkbConfig)
 public:
@@ -149,15 +148,6 @@ public:
      */
     static void createAboutData();
 
-    /**
-     * @returns the X11 Screen number. If not applicable it's set to @c -1.
-     */
-    static int x11ScreenNumber();
-    /**
-     * Sets the X11 screen number of this KWin instance to @p screenNumber.
-     */
-    static void setX11ScreenNumber(int screenNumber);
-
     /**
      * @returns the X11 root window.
      */

src/main_x11.cpp

@@ -108,8 +108,8 @@ class KWinSelectionOwner : public KSelectionOwner
 {
     Q_OBJECT
 public:
-    explicit KWinSelectionOwner(int screen)
-        : KSelectionOwner(make_selection_atom(screen), screen)
+    explicit KWinSelectionOwner()
+        : KSelectionOwner(make_selection_atom())
     {
     }
 
@@ -150,13 +150,9 @@ private:
         }
     }
 
-    xcb_atom_t make_selection_atom(int screen_P)
+    xcb_atom_t make_selection_atom()
     {
-        if (screen_P < 0) {
-            screen_P = QX11Info::appScreen();
-        }
-        QByteArray screen(QByteArrayLiteral("WM_S"));
-        screen.append(QByteArray::number(screen_P));
+        QByteArray screen(QByteArrayLiteral("WM_S0"));
         ScopedCPointer<xcb_intern_atom_reply_t> atom(xcb_intern_atom_reply(
             kwinApp()->x11Connection(),
             xcb_intern_atom_unchecked(kwinApp()->x11Connection(), false, screen.length(), screen.constData()),
@@ -209,28 +205,15 @@ void ApplicationX11::lostSelection()
     quit();
 }
 
-static xcb_screen_t *findXcbScreen(xcb_connection_t *connection, int screen)
-{
-    for (xcb_screen_iterator_t it = xcb_setup_roots_iterator(xcb_get_setup(connection));
-         it.rem;
-         --screen, xcb_screen_next(&it)) {
-        if (screen == 0) {
-            return it.data;
-        }
-    }
-    return nullptr;
-}
-
 void ApplicationX11::performStartup()
 {
     crashChecking();
 
-    if (Application::x11ScreenNumber() == -1) {
-        Application::setX11ScreenNumber(QX11Info::appScreen());
-    }
-    setX11DefaultScreen(findXcbScreen(x11Connection(), x11ScreenNumber()));
+    xcb_screen_t *screen = xcb_setup_roots_iterator(xcb_get_setup(x11Connection())).data;
+    Q_ASSERT(screen);
+    setX11DefaultScreen(screen);
 
-    owner.reset(new KWinSelectionOwner(Application::x11ScreenNumber()));
+    owner.reset(new KWinSelectionOwner());
     connect(owner.data(), &KSelectionOwner::failedToClaimOwnership, [] {
         fputs(i18n("kwin: unable to claim manager selection, another wm running? (try using --replace)\n").toLocal8Bit().constData(), stderr);
         ::exit(1);

src/netinfo.cpp

@@ -20,7 +20,6 @@
 
 namespace KWin
 {
-extern int screen_number;
 
 std::unique_ptr<RootInfo> RootInfo::s_self;
 
@@ -116,7 +115,7 @@ RootInfo *RootInfo::create()
         | NET::ActionChangeDesktop
         | NET::ActionClose;
 
-    s_self.reset(new RootInfo(supportWindow, "KWin", properties, types, states, properties2, actions, screen_number));
+    s_self.reset(new RootInfo(supportWindow, "KWin", properties, types, states, properties2, actions));
     return s_self.get();
 }
 

src/utils/xcbutils.h

@@ -1976,15 +1976,9 @@ static inline int defaultDepth()
     if (depth != 0) {
         return depth;
     }
-    int screen = Application::x11ScreenNumber();
-    for (xcb_screen_iterator_t it = xcb_setup_roots_iterator(xcb_get_setup(connection()));
-         it.rem;
-         --screen, xcb_screen_next(&it)) {
-        if (screen == 0) {
-            depth = it.data->root_depth;
-            break;
-        }
-    }
+    xcb_screen_t *screen = xcb_setup_roots_iterator(xcb_get_setup(connection())).data;
+    Q_ASSERT(screen);
+    depth = screen->root_depth;
     return depth;
 }
 

src/xwayland/xwayland.cpp

@@ -261,7 +261,6 @@ bool Xwayland::createX11Connection()
 
     m_app->setX11Connection(connection);
     m_app->setX11DefaultScreen(screen);
-    m_app->setX11ScreenNumber(0);
     m_app->setX11RootWindow(screen->root);
 
     m_app->createAtoms();
@@ -269,8 +268,8 @@ bool Xwayland::createX11Connection()
 
     installSocketNotifier();
 
-    // Note that it's very important to have valid x11RootWindow(), x11ScreenNumber(), and
-    // atoms when the rest of kwin is notified about the new X11 connection.
+    // Note that it's very important to have valid x11RootWindow(), and atoms when the
+    // rest of kwin is notified about the new X11 connection.
     Q_EMIT m_app->x11ConnectionChanged();
 
     return true;
@@ -292,7 +291,6 @@ void Xwayland::destroyX11Connection()
 
     m_app->setX11Connection(nullptr);
     m_app->setX11DefaultScreen(nullptr);
-    m_app->setX11ScreenNumber(-1);
     m_app->setX11RootWindow(XCB_WINDOW_NONE);
 
     Q_EMIT m_app->x11ConnectionChanged();