qt5-qtbase/0002-xcb-compare-to-previous-state-when-sending-geometry-.patch

From 56f6252e7285c9c61a99416fa2a8571fd67c597f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?=
 <tor.arne.vestbo@theqtcompany.com>
Date: Tue, 1 Dec 2015 16:27:09 +0100
Subject: [PATCH 02/12] xcb: compare to previous state when sending geometry
 and expose events
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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 <tor.arne.vestbo@theqtcompany.com>
---
 src/plugins/platforms/xcb/qxcbwindow.cpp | 33 ++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 6023ee6..98bcc62 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)
         return;
 
-    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;
-- 
2.5.0