Windows: Emit screen changed signal of top level windows.

Detect screen changes within virtual desktop in
handleGeometryChange(). Move away windows from screens being
destroyed.

Task-number: QTBUG-36659
Change-Id: I5bf4842cc21873a93bce0f70929308f11bd4d2fd
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

src/plugins/platforms/windows/qwindowsscreen.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the plugins of the Qt Toolkit.
@@ -407,6 +407,30 @@ static inline int indexOfMonitor(const QList<QWindowsScreenData> &screenData,
     return -1;
 }
 
+void QWindowsScreenManager::removeScreen(int index)
+{
+    qCDebug(lcQpaWindows) << "Removing Monitor:" << m_screens.at(index)->data();
+    QScreen *screen = m_screens.at(index)->screen();
+    QScreen *primaryScreen = QGuiApplication::primaryScreen();
+    // QTBUG-38650: When a screen is disconnected, Windows will automatically
+    // move the Window to another screen. This will trigger a geometry change
+    // event, but unfortunately after the screen destruction signal. To prevent
+    // QtGui from automatically hiding the QWindow, pretend all Windows move to
+    // the primary screen first (which is likely the correct, final screen).
+    if (screen != primaryScreen) {
+        unsigned movedWindowCount = 0;
+        foreach (QWindow *w, QGuiApplication::topLevelWindows()) {
+            if (w->screen() == screen && w->handle() && w->type() != Qt::Desktop) {
+                QWindowSystemInterface::handleWindowScreenChanged(w, primaryScreen);
+                ++movedWindowCount;
+            }
+        }
+        if (movedWindowCount)
+            QWindowSystemInterface::flushWindowSystemEvents();
+    }
+    delete m_screens.takeAt(index);
+}
+
 /*!
     \brief Synchronizes the screen list, adds new screens, removes deleted
     ones and propagates resolution changes to QWindowSystemInterface.
@@ -432,10 +456,8 @@ bool QWindowsScreenManager::handleScreenChanges()
     // temporary lock screen to avoid window recreation (QTBUG-33062).
     if (!lockScreen) {
         for (int i = m_screens.size() - 1; i >= 0; --i) {
-            if (indexOfMonitor(newDataList, m_screens.at(i)->data().name) == -1) {
-                qCDebug(lcQpaWindows) << "Removing Monitor: " << m_screens.at(i) ->data();
-                delete m_screens.takeAt(i);
-            } // not found
+            if (indexOfMonitor(newDataList, m_screens.at(i)->data().name) == -1)
+                removeScreen(i);
         }     // for existing screens
     }     // not lock screen
     return true;

src/plugins/platforms/windows/qwindowsscreen.h

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the plugins of the Qt Toolkit.
@@ -143,6 +143,8 @@ public:
     const WindowsScreenList &screens() const { return m_screens; }
 
 private:
+    void removeScreen(int index);
+
     WindowsScreenList m_screens;
     int m_lastDepth;
     WORD m_lastHorizontalResolution;

src/plugins/platforms/windows/qwindowswindow.cpp

@@ -1366,6 +1366,25 @@ void QWindowsWindow::handleResized(int wParam)
     }
 }
 
+// Return the effective screen for full screen mode in a virtual desktop.
+static QScreen *effectiveScreen(const QWindow *w)
+{
+    QRect geometry = w->geometry();
+    if (!w->isTopLevel())
+        geometry.moveTopLeft(w->mapToGlobal(geometry.topLeft()));
+
+    QScreen *screen = w->screen();
+    if (!screen->geometry().intersects(geometry)) {
+        foreach (QScreen *sibling, screen->virtualSiblings()) {
+            if (sibling->geometry().intersects(geometry)) {
+                screen = sibling;
+                break;
+            }
+        }
+    }
+    return screen;
+}
+
 void QWindowsWindow::handleGeometryChange()
 {
     //Prevent recursive resizes for Windows CE
@@ -1381,6 +1400,14 @@ void QWindowsWindow::handleGeometryChange()
         && !(m_data.geometry.width() > previousGeometry.width() || m_data.geometry.height() > previousGeometry.height())) {
         fireExpose(QRegion(m_data.geometry), true);
     }
+    if (previousGeometry.topLeft() != m_data.geometry.topLeft()) {
+        QWindow *w = window();
+        if (w->isTopLevel()) {
+            QScreen *newScreen = effectiveScreen(w);
+            if (newScreen != w->screen())
+                QWindowSystemInterface::handleWindowScreenChanged(w, newScreen);
+        }
+    }
     if (testFlag(SynchronousGeometryChangeEvent))
         QWindowSystemInterface::flushWindowSystemEvents();
 
@@ -1571,23 +1598,9 @@ void QWindowsWindow::setWindowState(Qt::WindowState state)
     }
 }
 
-// Return the effective screen for full screen mode in a virtual desktop.
-static const QScreen *effectiveScreen(const QWindow *w)
-{
-    QPoint center = w->geometry().center();
-    if (!w->isTopLevel())
-        center = w->mapToGlobal(center);
-    const QScreen *screen = w->screen();
-    if (!screen->geometry().contains(center))
-        foreach (const QScreen *sibling, screen->virtualSiblings())
-            if (sibling->geometry().contains(center))
-                return sibling;
-    return screen;
-}
-
 bool QWindowsWindow::isFullScreen_sys() const
 {
-    return window()->isTopLevel() && geometry_sys() == effectiveScreen(window())->geometry();
+    return window()->isTopLevel() && geometry_sys() == window()->screen()->geometry();
 }
 
 /*!
@@ -1667,7 +1680,7 @@ void QWindowsWindow::setWindowState_sys(Qt::WindowState newState)
             setStyle(newStyle);
             // Use geometry of QWindow::screen() within creation or the virtual screen the
             // window is in (QTBUG-31166, QTBUG-30724).
-            const QScreen *screen = testFlag(WithinCreate) ? window()->screen() : effectiveScreen(window());
+            const QScreen *screen = window()->screen();
             const QRect r = screen->geometry();
             const UINT swpf = SWP_FRAMECHANGED | SWP_NOACTIVATE;
             const bool wasSync = testFlag(SynchronousGeometryChangeEvent);
@@ -1934,7 +1947,7 @@ void QWindowsWindow::getSizeHints(MINMAXINFO *mmi) const
             && (m_data.flags & Qt::FramelessWindowHint)) {
         // This block fixes QTBUG-8361: Frameless windows shouldn't cover the
         // taskbar when maximized
-        if (const QScreen *screen = effectiveScreen(window())) {
+        if (const QScreen *screen = window()->screen()) {
             mmi->ptMaxSize.y = screen->availableGeometry().height();
 
             // Width, because you can have the taskbar on the sides too.