Make the expose region local on all platforms

QExposeEvent::region() reports a region in a random coordinate system.
The behavior is undocumented and the platform plugins do different things.

xcb, offscreen and ios are correct. These set the region in local coordinates,
which is the most logical interpretation of the expose region.

windows is almost correct, except for one occurrence.

cocoa and others need changes: passing in geometry() as the exposed region is
always wrong.

The patch documents the expected behavior both for QExposeEvent and
internally in QWindowSystemInterface. The problematic plugins are fixed to
use local coordinates.

Task-number: QTBUG-40470
Change-Id: I6ded3154d14254fa71d4292d8e1b5e6cf696c81a
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

10 files changed, 43 insertions, 20 deletions

diff --git a/src/gui/kernel/qevent.cpp b/src/gui/kernel/qevent.cpp
index a002aad387..1b853411f8 100644
--- a/src/gui/kernel/qevent.cpp
+++ b/src/gui/kernel/qevent.cpp
@@ -1307,7 +1307,8 @@ QMoveEvent::~QMoveEvent()
 */
 
 /*!
-    Constructs an expose event for the given \a exposeRegion.
+    Constructs an expose event for the given \a exposeRegion which must be
+    in local coordinates.
 */
 QExposeEvent::QExposeEvent(const QRegion &exposeRegion)
     : QEvent(Expose)
@@ -1325,7 +1326,7 @@ QExposeEvent::~QExposeEvent()
 /*!
     \fn const QRegion &QExposeEvent::region() const
 
-    Returns the window area that has been exposed.
+    Returns the window area that has been exposed. The region is given in local coordinates.
 */
 
 /*!
diff --git a/src/gui/kernel/qwindowsysteminterface.h b/src/gui/kernel/qwindowsysteminterface.h
index 1462c62e2b..580f1f86fa 100644
--- a/src/gui/kernel/qwindowsysteminterface.h
+++ b/src/gui/kernel/qwindowsysteminterface.h
@@ -138,6 +138,7 @@ public:
     static void handleTouchCancelEvent(QWindow *w, QTouchDevice *device, Qt::KeyboardModifiers mods = Qt::NoModifier);
     static void handleTouchCancelEvent(QWindow *w, ulong timestamp, QTouchDevice *device, Qt::KeyboardModifiers mods = Qt::NoModifier);
 
+    // rect is relative to parent
     static void handleGeometryChange(QWindow *w, const QRect &newRect, const QRect &oldRect = QRect());
     static void handleCloseEvent(QWindow *w, bool *accepted = 0);
     static void handleEnterEvent(QWindow *w, const QPointF &local = QPointF(), const QPointF& global = QPointF());
@@ -150,6 +151,7 @@ public:
 
     static void handleApplicationStateChanged(Qt::ApplicationState newState, bool forcePropagate = false);
 
+    // region is in local coordinates, do not confuse with geometry which is parent-relative
     static void handleExposeEvent(QWindow *tlw, const QRegion &region);
 
 #ifndef QT_NO_DRAGANDDROP
diff --git a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
index 7c39cb718d..d821145973 100644
--- a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
@@ -86,7 +86,7 @@ void QAndroidPlatformOpenGLWindow::setGeometry(const QRect &rect)
             && rect.height() > 0
             && availableGeometry.width() > 0
             && availableGeometry.height() > 0) {
-        QWindowSystemInterface::handleExposeEvent(window(), QRegion(rect));
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), rect.size()));
     }
 }
 
diff --git a/src/plugins/platforms/android/qandroidplatformscreen.cpp b/src/plugins/platforms/android/qandroidplatformscreen.cpp
index 529ae0a80d..433461f628 100644
--- a/src/plugins/platforms/android/qandroidplatformscreen.cpp
+++ b/src/plugins/platforms/android/qandroidplatformscreen.cpp
@@ -243,7 +243,7 @@ void QAndroidPlatformScreen::setAvailableGeometry(const QRect &rect)
             if (w->handle()) {
                 QRect geometry = w->handle()->geometry();
                 if (geometry.width() > 0 && geometry.height() > 0)
-                    QWindowSystemInterface::handleExposeEvent(w, QRegion(geometry));
+                    QWindowSystemInterface::handleExposeEvent(w, QRect(QPoint(0, 0), geometry.size()));
             }
         }
     }
diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 29b983cd89..7e22351818 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -516,7 +516,7 @@ void QCocoaWindow::setCocoaGeometry(const QRect &rect)
 
         // call this here: updateGeometry in qnsview.mm is a no-op for this case
         QWindowSystemInterface::handleGeometryChange(window(), rect);
-        QWindowSystemInterface::handleExposeEvent(window(), rect);
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), rect.size()));
     } else if (m_nsWindow) {
         NSRect bounds = qt_mac_flipRect(rect);
         [m_nsWindow setFrame:[m_nsWindow frameRectForContentRect:bounds] display:YES animate:NO];
@@ -1749,7 +1749,7 @@ void QCocoaWindow::exposeWindow()
         m_isExposed = true;
         m_exposedGeometry = geometry();
         m_exposedDevicePixelRatio = devicePixelRatio();
-        QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), m_exposedGeometry.size()));
     }
 }
 
@@ -1780,7 +1780,7 @@ void QCocoaWindow::updateExposedGeometry()
     m_isExposed = true;
     m_exposedGeometry = geometry();
     m_exposedDevicePixelRatio = devicePixelRatio();
-    QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
+    QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), m_exposedGeometry.size()));
 }
 
 QWindow *QCocoaWindow::childWindowAt(QPoint windowPoint)
diff --git a/src/plugins/platforms/directfb/qdirectfbwindow.cpp b/src/plugins/platforms/directfb/qdirectfbwindow.cpp
index 670a955bd6..8d7eeb3cd9 100644
--- a/src/plugins/platforms/directfb/qdirectfbwindow.cpp
+++ b/src/plugins/platforms/directfb/qdirectfbwindow.cpp
@@ -137,7 +137,7 @@ void QDirectFbWindow::setVisible(bool visible)
     }
 
     if (window()->isTopLevel() && visible)
-        QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), window()->geometry()));
 }
 
 void QDirectFbWindow::setWindowFlags(Qt::WindowFlags flags)
diff --git a/src/plugins/platforms/eglfs/qeglfswindow.cpp b/src/plugins/platforms/eglfs/qeglfswindow.cpp
index a0150b7ade..1f67170efc 100644
--- a/src/plugins/platforms/eglfs/qeglfswindow.cpp
+++ b/src/plugins/platforms/eglfs/qeglfswindow.cpp
@@ -98,7 +98,7 @@ void QEglFSWindow::create()
 
     m_flags |= HasNativeWindow;
     setGeometry(QRect()); // will become fullscreen
-    QWindowSystemInterface::handleExposeEvent(window(), geometry());
+    QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), geometry().size()));
 
     EGLDisplay display = static_cast<QEglFSScreen *>(screen)->display();
     QSurfaceFormat platformFormat = QEglFSHooks::hooks()->surfaceFormatFor(window()->requestedFormat());
@@ -168,8 +168,9 @@ void QEglFSWindow::resetSurface()
 void QEglFSWindow::setVisible(bool visible)
 {
     QList<QEGLPlatformWindow *> windows = screen()->windows();
+    QWindow *wnd = window();
 
-    if (window()->type() != Qt::Desktop) {
+    if (wnd->type() != Qt::Desktop) {
         if (visible) {
             screen()->addWindow(this);
         } else {
@@ -180,7 +181,7 @@ void QEglFSWindow::setVisible(bool visible)
         }
     }
 
-    QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+    QWindowSystemInterface::handleExposeEvent(wnd, QRect(QPoint(0, 0), wnd->geometry().size()));
 
     if (visible)
         QWindowSystemInterface::flushWindowSystemEvents();
@@ -218,15 +219,17 @@ void QEglFSWindow::requestActivateWindow()
     if (window()->type() != Qt::Desktop)
         screen()->moveToTop(this);
 
-    QWindowSystemInterface::handleWindowActivated(window());
-    QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+    QWindow *wnd = window();
+    QWindowSystemInterface::handleWindowActivated(wnd);
+    QWindowSystemInterface::handleExposeEvent(wnd, QRect(QPoint(0, 0), wnd->geometry().size()));
 }
 
 void QEglFSWindow::raise()
 {
-    if (window()->type() != Qt::Desktop) {
+    QWindow *wnd = window();
+    if (wnd->type() != Qt::Desktop) {
         screen()->moveToTop(this);
-        QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+        QWindowSystemInterface::handleExposeEvent(wnd, QRect(QPoint(0, 0), wnd->geometry().size()));
     }
 }
 
@@ -237,7 +240,8 @@ void QEglFSWindow::lower()
         int idx = windows.indexOf(this);
         if (idx > 0) {
             screen()->changeWindowIndex(this, idx - 1);
-            QWindowSystemInterface::handleExposeEvent(windows.last()->window(), windows.last()->geometry());
+            QWindowSystemInterface::handleExposeEvent(windows.last()->window(),
+                                                      QRect(QPoint(0, 0), windows.last()->geometry().size()));
         }
     }
 }
diff --git a/src/plugins/platforms/qnx/qqnxwindow.cpp b/src/plugins/platforms/qnx/qqnxwindow.cpp
index 5a405f9577..56f17e6d11 100644
--- a/src/plugins/platforms/qnx/qqnxwindow.cpp
+++ b/src/plugins/platforms/qnx/qqnxwindow.cpp
@@ -252,7 +252,7 @@ void QQnxWindow::setGeometry(const QRect &rect)
         setGeometryHelper(newGeometry);
 
     if (isExposed())
-        QWindowSystemInterface::handleExposeEvent(window(), newGeometry);
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), newGeometry.size()));
 }
 
 void QQnxWindow::setGeometryHelper(const QRect &rect)
@@ -306,7 +306,7 @@ void QQnxWindow::setVisible(bool visible)
 
     root->updateVisibility(root->m_visible);
 
-    QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+    QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), window()->geometry().size()));
 
     if (visible) {
         applyWindowState();
@@ -345,7 +345,7 @@ void QQnxWindow::setExposed(bool exposed)
 
     if (m_exposed != exposed) {
         m_exposed = exposed;
-        QWindowSystemInterface::handleExposeEvent(window(), window()->geometry());
+        QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(0, 0), window()->geometry().size()));
     }
 }
 
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index c5978c125c..3b54feabbf 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -1389,7 +1389,7 @@ void QWindowsWindow::handleGeometryChange()
     // expose events when shrinking, synthesize.
     if (!testFlag(OpenGL_ES2) && isExposed()
         && !(m_data.geometry.width() > previousGeometry.width() || m_data.geometry.height() > previousGeometry.height())) {
-        fireExpose(QRegion(m_data.geometry), true);
+        fireExpose(QRect(QPoint(0, 0), m_data.geometry.size()), true);
     }
     if (previousGeometry.topLeft() != m_data.geometry.topLeft()) {
         QPlatformScreen *newScreen = screenForGeometry(m_data.geometry);
diff --git a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
index 02f3959802..b4659b7caf 100644
--- a/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
+++ b/tests/auto/gui/kernel/qwindow/tst_qwindow.cpp
@@ -164,6 +164,8 @@ public:
     {
         m_received[event->type()]++;
         m_order << event->type();
+        if (event->type() == QEvent::Expose)
+            m_exposeRegion = static_cast<QExposeEvent *>(event)->region();
 
         return QWindow::event(event);
     }
@@ -178,9 +180,15 @@ public:
         return m_order.indexOf(type);
     }
 
+    QRegion exposeRegion() const
+    {
+        return m_exposeRegion;
+    }
+
 private:
     QHash<QEvent::Type, int> m_received;
     QVector<QEvent::Type> m_order;
+    QRegion m_exposeRegion;
 };
 
 void tst_QWindow::eventOrderOnShow()
@@ -358,6 +366,14 @@ void tst_QWindow::isExposed()
     QTRY_VERIFY(window.received(QEvent::Expose) > 0);
     QTRY_VERIFY(window.isExposed());
 
+    // This is a top-level window so assuming it is completely exposed, the
+    // expose region must be (0, 0), (width, height). If this is not the case,
+    // the platform plugin is sending expose events with a region in an
+    // incorrect coordinate system.
+    QRect r = window.exposeRegion().boundingRect();
+    r = QRect(window.mapToGlobal(r.topLeft()), r.size());
+    QCOMPARE(r, window.geometry());
+
     window.hide();
 
     QCoreApplication::processEvents();