path: root/src/plugins
diff options
authorTor Arne Vestbø <>2015-12-01 16:27:09 +0100
committerTor Arne Vestbø <>2015-12-10 17:27:00 +0000
commit56f6252e7285c9c61a99416fa2a8571fd67c597f (patch)
treef420c68a6110aa30e9c4f74259524fcb5662a670 /src/plugins
parent40c927e7331ea4ac9ca50de48560b700e657cded (diff)
xcb: compare to previous state when sending geometry and expose events
By calculating the previous geometry and passing it on when calling handleGeometryChange we can detect cases where setGeometry() on a QWindow didn't result in the expected geometry. The new (actual) geometry is delivered as a resize event. This also allows us to only send expose events when the size of the window has actually changed (instead of also sending when the window has just moved). Due to the async delivery of geometry changes on the xcb platform we need to avoid using QWindowPrivate's cached state of the geometry, as that will result in duplicate resize events when events are not flushed in between two system resize events coming in with the same size. Change-Id: I3d4abe4a1095dd96e6e354288d5b646c623c30dd Reviewed-by: Tor Arne Vestbø <>
Diffstat (limited to 'src/plugins')
1 files changed, 27 insertions, 6 deletions
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 6023ee6b29..98bcc62d4c 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -2007,21 +2007,42 @@ void QXcbWindow::handleConfigureNotifyEvent(const xcb_configure_notify_event_t *
- const QRect rect = QRect(pos, QSize(event->width, event->height));
- QPlatformScreen *newScreen = parent() ? parent()->screen() : screenForGeometry(rect);
+ // The original geometry requested by setGeometry() might be different
+ // from what we end up with after applying window constraints.
+ QRect requestedGeometry = geometry();
+ const QRect actualGeometry = QRect(pos, QSize(event->width, event->height));
+ QPlatformScreen *newScreen = parent() ? parent()->screen() : screenForGeometry(actualGeometry);
QXcbScreen *currentScreen = m_xcbScreen;
m_xcbScreen = static_cast<QXcbScreen*>(newScreen);
if (!newScreen)
- QPlatformWindow::setGeometry(rect);
- QWindowSystemInterface::handleGeometryChange(window(), rect);
+ // Persist the actual geometry so that QWindow::geometry() can
+ // be queried in the resize event.
+ QPlatformWindow::setGeometry(actualGeometry);
+ // As we're delivering the geometry change through QPA in n async fashion we can't
+ // pass on the current geometry of the QWindowPrivate, as that may have not been
+ // updated yet by a geometry change that's still in the QPA event queue. Instead
+ // we fall back to the default argument value of QRect(), which will result in
+ // QGuiApplication looking up the previous geometry from QWindowPrivate, but this
+ // time in sync with the even delivery/processing.
+ QWindowSystemInterface::handleGeometryChange(window(), actualGeometry,
+ requestedGeometry != actualGeometry ? requestedGeometry : QRect());
if (newScreen != currentScreen)
QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->screen());
- if (m_mapped)
- QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(), geometry().size()));
+ // For expose events we have no way of telling QGuiApplication to used the locally
+ // cached version of the previous state, so we may in some situations end up with
+ // an additional expose event.
+ QRect previousGeometry = requestedGeometry != actualGeometry ?
+ requestedGeometry : qt_window_private(window())->geometry;
+ if (m_mapped && actualGeometry.size() != previousGeometry.size())
+ QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(), actualGeometry.size()));
if (m_usingSyncProtocol && m_syncState == SyncReceived)
m_syncState = SyncAndConfigureReceived;