xcb: Process _NET_WORKAREA and screen geometry changes separately

This commit allows to avoid superfluous calls to the X server.
We don't request _NET_WORKAREA values when the screen geometry changes,
and we avoid RandR calls on each _NET_WORKAREA change.
Besides, update the available geometry of all screens with the
same root window, rather than only that one which corresponds
to Qt::Desktop window.

Change-Id: I5ec624717f5f261c986cd9aaf2425f22985e11c0
Reviewed-by: Błażej Szczygieł <spaz16@wp.pl>
Reviewed-by: Uli Schlachter <psychon@znc.in>
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index e4eaeef5d8..901764bbf8 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -1121,8 +1121,17 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
             handled = false;
             break;
         case XCB_PROPERTY_NOTIFY:
-            HANDLE_PLATFORM_WINDOW_EVENT(xcb_property_notify_event_t, window, handlePropertyNotifyEvent);
+        {
+            xcb_property_notify_event_t *pn = (xcb_property_notify_event_t *)event;
+            if (pn->atom == atom(QXcbAtom::_NET_WORKAREA)) {
+                QXcbVirtualDesktop *virtualDesktop = virtualDesktopForRootWindow(pn->window);
+                if (virtualDesktop)
+                    virtualDesktop->updateWorkArea();
+            } else {
+                HANDLE_PLATFORM_WINDOW_EVENT(xcb_property_notify_event_t, window, handlePropertyNotifyEvent);
+            }
             break;
+        }
 #if defined(XCB_USE_XINPUT2)
         case XCB_GE_GENERIC:
             // Here the windowEventListener is invoked from xi2HandleEvent()