use selection changed events from XFixes

properly initialize the XFixes extension and then
use the selection changed events to notify
Qt apps.

Reviewed-by: Samuel

src/plugins/platforms/xcb/qxcbclipboard.cpp

@@ -163,6 +163,28 @@ QXcbClipboard::QXcbClipboard(QXcbConnection *c)
     m_timestamp[QClipboard::Selection] = XCB_CURRENT_TIME;
 
     m_screen = connection()->screens().at(connection()->primaryScreen());
+
+    int x = 0, y = 0, w = 3, h = 3;
+
+    m_owner = xcb_generate_id(xcb_connection());
+    Q_XCB_CALL(xcb_create_window(xcb_connection(),
+                                 XCB_COPY_FROM_PARENT,            // depth -- same as root
+                                 m_owner,                        // window id
+                                 m_screen->screen()->root,                   // parent window id
+                                 x, y, w, h,
+                                 0,                               // border width
+                                 XCB_WINDOW_CLASS_INPUT_OUTPUT,   // window class
+                                 m_screen->screen()->root_visual, // visual
+                                 0,                               // value mask
+                                 0));                             // value list
+
+    if (connection()->hasXFixes()) {
+        const uint32_t mask = XCB_XFIXES_SELECTION_EVENT_MASK_SET_SELECTION_OWNER |
+                XCB_XFIXES_SELECTION_EVENT_MASK_SELECTION_WINDOW_DESTROY |
+                XCB_XFIXES_SELECTION_EVENT_MASK_SELECTION_CLIENT_CLOSE;
+        Q_XCB_CALL(xcb_xfixes_select_selection_input_checked(xcb_connection(), m_owner, XCB_ATOM_PRIMARY, mask));
+        Q_XCB_CALL(xcb_xfixes_select_selection_input_checked(xcb_connection(), m_owner, atom(QXcbAtom::CLIPBOARD), mask));
+    }
 }
 
 QXcbClipboard::~QXcbClipboard()
@@ -322,24 +344,6 @@ void QXcbClipboard::setRequestor(xcb_window_t window)
 
 xcb_window_t QXcbClipboard::owner() const
 {
-    if (!m_owner) {
-        int x = 0, y = 0, w = 3, h = 3;
-
-        xcb_window_t window = xcb_generate_id(xcb_connection());
-        Q_XCB_CALL(xcb_create_window(xcb_connection(),
-                                     XCB_COPY_FROM_PARENT,            // depth -- same as root
-                                     window,                        // window id
-                                     m_screen->screen()->root,                   // parent window id
-                                     x, y, w, h,
-                                     0,                               // border width
-                                     XCB_WINDOW_CLASS_INPUT_OUTPUT,   // window class
-                                     m_screen->screen()->root_visual, // visual
-                                     0,                               // value mask
-                                     0));                             // value list
-
-        QXcbClipboard *that = const_cast<QXcbClipboard *>(this);
-        that->m_owner = window;
-    }
     return m_owner;
 }
 
@@ -554,6 +558,16 @@ void QXcbClipboard::handleSelectionRequest(xcb_selection_request_event_t *req)
     xcb_send_event(xcb_connection(), false, req->requestor, XCB_EVENT_MASK_NO_EVENT, (const char *)&event);
 }
 
+void QXcbClipboard::handleXFixesSelectionRequest(xcb_xfixes_selection_notify_event_t *event)
+{
+    QClipboard::Mode mode = modeForAtom(event->selection);
+    if (event->owner != owner() && m_clientClipboard[mode] && m_timestamp[mode] < event->selection_timestamp) {
+        setMimeData(0, mode);
+        emitChanged(mode);
+    }
+}
+
+
 static inline int maxSelectionIncr(xcb_connection_t *c)
 {
     int l = xcb_get_maximum_request_length(c);

src/plugins/platforms/xcb/qxcbclipboard.h

@@ -45,6 +45,7 @@
 #include <QPlatformClipboard>
 #include <qxcbobject.h>
 #include <xcb/xcb.h>
+#include <xcb/xfixes.h>
 
 class QXcbConnection;
 class QXcbScreen;
@@ -71,6 +72,7 @@ public:
 
     void handleSelectionRequest(xcb_selection_request_event_t *event);
     void handleSelectionClearRequest(xcb_selection_clear_event_t *event);
+    void handleXFixesSelectionRequest(xcb_xfixes_selection_notify_event_t *event);
 
     bool clipboardReadProperty(xcb_window_t win, xcb_atom_t property, bool deleteProperty, QByteArray *buffer, int *size, xcb_atom_t *type, int *format) const;
     QByteArray clipboardReadIncrementalProperty(xcb_window_t win, xcb_atom_t property, int nbytes, bool nullterm);

src/plugins/platforms/xcb/qxcbconnection.cpp

@@ -90,6 +90,7 @@ QXcbConnection::QXcbConnection(const char *displayName)
     , m_dri2_support_probed(false)
     , m_has_support_for_dri2(false)
 #endif
+    , xfixes_first_event(0)
 {
     m_primaryScreen = 0;
 
@@ -110,6 +111,8 @@ QXcbConnection::QXcbConnection(const char *displayName)
     m_connection = xcb_connect(m_displayName.constData(), &primaryScreen);
 
 #endif //XCB_USE_XLIB
+    xcb_prefetch_extension_data (m_connection, &xcb_xfixes_id);
+
     m_setup = xcb_get_setup(xcb_connection());
 
     initializeAllAtoms();
@@ -124,14 +127,14 @@ QXcbConnection::QXcbConnection(const char *displayName)
         xcb_screen_next(&it);
     }
 
+    initializeXFixes();
+    initializeXRender();
+
     m_wmSupport = new QXcbWMSupport(this);
     m_keyboard = new QXcbKeyboard(this);
     m_clipboard = new QXcbClipboard(this);
     m_drag = new QXcbDrag(this);
 
-    initializeXFixes();
-    initializeXRender();
-
 #ifdef XCB_USE_DRI2
     initializeDri2();
 #endif
@@ -506,6 +509,15 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
         handled = false;
         break;
     }
+
+    if (!handled) {
+        if (response_type == xfixes_first_event + XCB_XFIXES_SELECTION_NOTIFY) {
+            setTime(((xcb_xfixes_selection_notify_event_t *)event)->timestamp);
+            m_clipboard->handleXFixesSelectionRequest((xcb_xfixes_selection_notify_event_t *)event);
+            handled = true;
+        }
+    }
+
     if (handled)
         printXcbEvent("Handled XCB event", event);
     else
@@ -842,7 +854,9 @@ void QXcbConnection::sync()
 void QXcbConnection::initializeXFixes()
 {
     xcb_generic_error_t *error = 0;
-    xcb_prefetch_extension_data (m_connection, &xcb_xfixes_id);
+    const xcb_query_extension_reply_t *reply = xcb_get_extension_data(m_connection, &xcb_xfixes_id);
+    xfixes_first_event = reply->first_event;
+
     xcb_xfixes_query_version_cookie_t xfixes_query_cookie = xcb_xfixes_query_version(m_connection,
                                                                                      XCB_XFIXES_MAJOR_VERSION,
                                                                                      XCB_XFIXES_MINOR_VERSION);
@@ -851,8 +865,10 @@ void QXcbConnection::initializeXFixes()
     if (!xfixes_query || error || xfixes_query->major_version < 2) {
         qWarning("Failed to initialize XFixes");
         free(error);
+        xfixes_first_event = 0;
     }
     free(xfixes_query);
+
 }
 
 void QXcbConnection::initializeXRender()

src/plugins/platforms/xcb/qxcbconnection.h

@@ -286,6 +286,8 @@ public:
     inline xcb_timestamp_t time() const { return m_time; }
     inline void setTime(xcb_timestamp_t t) { if (t > m_time) m_time = t; }
 
+    bool hasXFixes() const { return xfixes_first_event > 0; }
+
 private slots:
     void processXcbEvents();
 
@@ -347,6 +349,8 @@ private:
     WindowMapper m_mapper;
 
     QVector<PeekFunc> m_peekFuncs;
+
+    uint32_t xfixes_first_event;
 };
 
 #define DISPLAY_FROM_XCB(object) ((Display *)(object->connection()->xlib_display()))