Provide x11RootWindow as a property on the KWin::Application

KWin::rootWindow() uses the property to resolve the value instead of
using QX11Info. In practice this doesn't change anything at the moment,
but allows kwin_wayland to provide a root window without depending on
QX11Info.

autotests/test_client_machine.cpp

@@ -82,6 +82,8 @@ void TestClientMachine::initTestCase()
         }
     }
     freeaddrinfo(res);
+
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(QX11Info::appRootWindow()));
 }
 
 void TestClientMachine::cleanupTestCase()

autotests/test_screen_edges.cpp

@@ -134,6 +134,7 @@ private Q_SLOTS:
 
 void TestScreenEdges::initTestCase()
 {
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(QX11Info::appRootWindow()));
     KWin::atoms = new KWin::Atoms;
     qRegisterMetaType<KWin::ElectricBorder>();
 }

autotests/test_xcb_size_hints.cpp

@@ -35,6 +35,7 @@ class TestXcbSizeHints : public QObject
 {
     Q_OBJECT
 private Q_SLOTS:
+    void initTestCase();
     void init();
     void cleanup();
     void testSizeHints_data();
@@ -48,6 +49,11 @@ private:
     Window m_testWindow;
 };
 
+void TestXcbSizeHints::initTestCase()
+{
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(QX11Info::appRootWindow()));
+}
+
 void TestXcbSizeHints::init()
 {
     const uint32_t values[] = { true };

autotests/test_xcb_window.cpp

@@ -32,6 +32,7 @@ class TestXcbWindow : public QObject
 {
     Q_OBJECT
 private Q_SLOTS:
+    void initTestCase();
     void defaultCtor();
     void ctor();
     void classCtor();
@@ -42,6 +43,11 @@ private Q_SLOTS:
     void destroyNotManaged();
 };
 
+void TestXcbWindow::initTestCase()
+{
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(QX11Info::appRootWindow()));
+}
+
 void TestXcbWindow::defaultCtor()
 {
     Xcb::Window window;

autotests/test_xcb_wrapper.cpp

@@ -34,6 +34,7 @@ class TestXcbWrapper : public QObject
 {
     Q_OBJECT
 private Q_SLOTS:
+    void initTestCase();
     void init();
     void cleanup();
     void defaultCtor();
@@ -60,6 +61,11 @@ private:
     Window m_testWindow;
 };
 
+void TestXcbWrapper::initTestCase()
+{
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(QX11Info::appRootWindow()));
+}
+
 void TestXcbWrapper::init()
 {
     const uint32_t values[] = { true };

autotests/test_xrandr_screens.cpp

@@ -39,10 +39,6 @@ QPoint Cursor::pos()
 static xcb_window_t s_rootWindow = XCB_WINDOW_NONE;
 static xcb_connection_t *s_connection = nullptr;
 
-unsigned long QX11Info::appRootWindow(int)
-{
-    return s_rootWindow;
-}
 xcb_connection_t *QX11Info::connection()
 {
     return s_connection;
@@ -101,6 +97,7 @@ void TestXRandRScreens::initTestCase()
         }
     }
     QVERIFY(s_rootWindow != XCB_WINDOW_NONE);
+    qApp->setProperty("x11RootWindow", QVariant::fromValue<quint32>(s_rootWindow));
 
     // get the extensions
     if (!Extensions::self()->isRandrAvailable()) {

libkwineffects/kwinglobals.h

@@ -24,6 +24,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QCoreApplication>
 #include <QVariant>
 #include <QtX11Extras/QX11Info>
+#include <QCoreApplication>
+#include <QVariant>
 
 #include <kwin_export.h>
 
@@ -150,7 +152,7 @@ KWIN_EXPORT xcb_window_t rootWindow()
 {
     static xcb_window_t s_rootWindow = XCB_WINDOW_NONE;
     if (s_rootWindow == XCB_WINDOW_NONE) {
-        s_rootWindow = QX11Info::appRootWindow();
+        s_rootWindow = qApp->property("x11RootWindow").value<quint32>();
     }
     return s_rootWindow;
 }

main.cpp

@@ -148,6 +148,7 @@ Application::Application(Application::OperationMode mode, int &argc, char **argv
     , m_configLock(false)
     , m_operationMode(mode)
 {
+    setX11RootWindow(QX11Info::appRootWindow());
     qRegisterMetaType<Options::WindowOperation>("Options::WindowOperation");
 }
 

main.h

@@ -46,6 +46,7 @@ class KWIN_EXPORT Application : public  QApplication
 {
     Q_OBJECT
     Q_PROPERTY(quint32 x11Time READ x11Time WRITE setX11Time)
+    Q_PROPERTY(quint32 x11RootWindow READ x11RootWindow CONSTANT)
 public:
     /**
     * @brief This enum provides the various operation modes of KWin depending on the available
@@ -119,6 +120,13 @@ public:
      */
     static void setX11MultiHead(bool multiHead);
 
+    /**
+     * @returns the X11 root window.
+     **/
+    xcb_window_t x11RootWindow() const {
+        return m_rootWindow;
+    }
+
     static void setupMalloc();
     static void setupLocalizedString();
     static void setupLoggingCategoryFilters();
@@ -136,6 +144,13 @@ protected:
     void createOptions();
     void setupEventFilters();
     void destroyWorkspace();
+    /**
+     * Inheriting classes should use this method to set the X11 root window
+     * before accessing any X11 specific code pathes.
+     **/
+    void setX11RootWindow(xcb_window_t root) {
+        m_rootWindow = root;
+    }
 
     bool notify(QObject* o, QEvent* e);
     static void crashHandler(int signal);
@@ -149,6 +164,7 @@ private:
     bool m_configLock;
     OperationMode m_operationMode;
     xcb_timestamp_t m_x11Time = XCB_TIME_CURRENT_TIME;
+    xcb_window_t m_rootWindow = XCB_WINDOW_NONE;
     static int crashes;
 };