Complete rewrite of threaded render loop.

This change starts using the superior implementation of the scene graph
render loop which has been worked on in the scenegraph-playground
project for a while. It uses a far more straightforward locking/sync
paradigm compared to the existing one and is less deadlock and error
prone. It also enables the scene graph thread to run on its own when
the GUI thread is blocked, enabling threaded animations.

This changes also introduces a naming change inside Qt Quick from
"Window Manager" -> "Render Loop" as that fits better to what the
code does.

Change-Id: I1c2170ee04fcbef79660bd7dae6cace647cdb276
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

9 files changed, 55 insertions, 1573 deletions

diff --git a/src/quick/items/context2d/qquickcontext2d.cpp b/src/quick/items/context2d/qquickcontext2d.cpp
index a46cd6ab70..c857a69f75 100644
--- a/src/quick/items/context2d/qquickcontext2d.cpp
+++ b/src/quick/items/context2d/qquickcontext2d.cpp
@@ -62,7 +62,6 @@
 #include <private/qv8domerrors_p.h>
 #include <QtCore/qnumeric.h>
 #include <private/qquickwindow_p.h>
-#include <private/qquickwindowmanager_p.h>
 
 #if defined(Q_OS_QNX) || defined(Q_OS_LINUX_ANDROID)
 #include <ctype.h>
@@ -3348,7 +3347,6 @@ QQuickContext2D::QQuickContext2D(QObject *parent)
     : QQuickCanvasContext(parent)
     , m_buffer(new QQuickContext2DCommandBuffer)
     , m_v8engine(0)
-    , m_windowManager(0)
     , m_surface(0)
     , m_glContext(0)
     , m_thread(0)
@@ -3380,7 +3378,6 @@ void QQuickContext2D::init(QQuickCanvasItem *canvasItem, const QVariantMap &args
     m_renderTarget = canvasItem->renderTarget();
 
     QQuickWindow *window = canvasItem->window();
-    m_windowManager =  QQuickWindowPrivate::get(window)->windowManager;
     m_renderStrategy = canvasItem->renderStrategy();
 
     switch (m_renderTarget) {
diff --git a/src/quick/items/context2d/qquickcontext2d_p.h b/src/quick/items/context2d/qquickcontext2d_p.h
index 2124c731b2..8d96ab579b 100644
--- a/src/quick/items/context2d/qquickcontext2d_p.h
+++ b/src/quick/items/context2d/qquickcontext2d_p.h
@@ -70,7 +70,6 @@ class QQuickContext2DCommandBuffer;
 class QQuickContext2DTexture;
 class QQuickPixmap;
 class QSGTexture;
-class QQuickWindowManager;
 class QSurface;
 class QOpenGLContext;
 
@@ -240,7 +239,6 @@ public:
     v8::Local<v8::Value> m_strokeStyle;
     v8::Handle<v8::Value> m_v8path;
     QV8Engine *m_v8engine;
-    QQuickWindowManager *m_windowManager;
     QSurface *m_surface;
     QOpenGLContext *m_glContext;
     v8::Persistent<v8::Object> m_v8value;
diff --git a/src/quick/items/items.pri b/src/quick/items/items.pri
index 13abf7b958..5272a3d5f7 100644
--- a/src/quick/items/items.pri
+++ b/src/quick/items/items.pri
@@ -74,9 +74,7 @@ HEADERS += \
     $$PWD/qquickitemview_p_p.h \
     $$PWD/qquickitemviewtransition_p.h \
     $$PWD/qquickscreen_p.h \
-    $$PWD/qquickwindowmodule_p.h \
-    $$PWD/qquickwindowmanager_p.h \
-    $$PWD/qquickthreadedwindowmanager_p.h
+    $$PWD/qquickwindowmodule_p.h
 
 SOURCES += \
     $$PWD/qquickevents.cpp \
@@ -128,9 +126,7 @@ SOURCES += \
     $$PWD/qquickitemview.cpp \
     $$PWD/qquickitemviewtransition.cpp \
     $$PWD/qquickwindowmodule.cpp \
-    $$PWD/qquickscreen.cpp \
-    $$PWD/qquickwindowmanager.cpp \
-    $$PWD/qquickthreadedwindowmanager.cpp
+    $$PWD/qquickscreen.cpp
 
 SOURCES += \
     $$PWD/qquickshadereffect.cpp \
diff --git a/src/quick/items/qquickthreadedwindowmanager.cpp b/src/quick/items/qquickthreadedwindowmanager.cpp
deleted file mode 100644
index 6c7b9c0448..0000000000
--- a/src/quick/items/qquickthreadedwindowmanager.cpp
+++ /dev/null
@@ -1,910 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/legal
-**
-** This file is part of the QtQml module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and Digia.  For licensing terms and
-** conditions see http://qt.digia.com/licensing.  For further information
-** use the contact form at http://qt.digia.com/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 2.1 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU Lesser General Public License version 2.1 requirements
-** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
-**
-** In addition, as a special exception, Digia gives you certain additional
-** rights.  These rights are described in the Digia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3.0 as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU General Public License version 3.0 requirements will be
-** met: http://www.gnu.org/copyleft/gpl.html.
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "qquickwindowmanager_p.h"
-#include "qquickthreadedwindowmanager_p.h"
-
-#include <QtCore/QTime>
-#include <QtCore/QDebug>
-
-#include <QtGui/QOpenGLContext>
-#include <QtGui/private/qguiapplication_p.h>
-#include <qpa/qplatformintegration.h>
-
-#include <QtQml/private/qqmlglobal_p.h>
-
-#include <QtQuick/QQuickWindow>
-#include <QtQuick/private/qquickwindow_p.h>
-
-QT_BEGIN_NAMESPACE
-
-//#define THREAD_DEBUG
-extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha);
-
-const QEvent::Type QEvent_Sync = QEvent::Type(QEvent::User);
-const QEvent::Type QEvent_DeferredUpdate = QEvent::Type(QEvent::User + 1);
-
-#define QQUICK_RENDER_TIMING
-#ifdef QQUICK_RENDER_TIMING
-DEFINE_BOOL_CONFIG_OPTION(qquick_render_timing, QML_RENDER_TIMING)
-static QTime threadTimer;
-static int syncTime;
-static int renderTime;
-static int swapTime;
-#endif
-
-
-/*
-  Threaded Rendering
-  ==================
-
-  The threaded rendering uses a number of different variables to track potential
-  states used to handle resizing, initial paint, grabbing and driving animations
-  while ALWAYS keeping the GL context in the rendering thread and keeping the
-  overhead of normal one-shot paints and vblank driven animations at a minimum.
-
-  Resize, initial show and grab suffer slightly in this model as they are locked
-  to the rendering in the rendering thread, but this is a necessary evil for
-  the system to work.
-
-  Variables that are used:
-
-  Private::animationRunning: This is true while the animations are running, and only
-  written to inside locks.
-
-  RenderThread::isGuiLocked: This is used to indicate that the GUI thread owns the
-  lock. This variable is an integer to allow for recursive calls to lockInGui()
-  without using a recursive mutex. See isPostingSyncEvent.
-
-  RenderThread::isPostingSyncEvent: This variable is set in the render thread just
-  before the sync event is sent to the GUI thread. It is used to avoid deadlocks
-  in the case where render thread waits while waiting for GUI to pick up the sync
-  event and GUI thread gets a resizeEvent, the initial paintEvent or a grab.
-  When this happens, we use the
-  exhaustSyncEvent() function to do the sync right there and mark the coming
-  sync event to be discarded. There can only ever be one sync incoming.
-
-  RenderThread::isRenderBlock: This variable is true when animations are not
-  running and the render thread has gone to sleep, waiting for more to do.
-
-  RenderThread::isExternalUpdatePending: This variable is set to false when
-  a new render pass is started and to true in maybeUpdate(). It is an
-  indication to the render thread that another render pass needs to take
-  place, rather than the render thread going to sleep after completing its swap.
-
-  RenderThread::doGrab: This variable is set by the grab() function and
-  tells the renderer to do a grab after rendering is complete and before
-  swapping happens.
-
-  RenderThread::shouldExit: This variable is used to determine if the render
-  thread should do a nother pass. It is typically set as a result of show()
-  and unset as a result of hide() or during shutdown()
-
-  RenderThread::hasExited: Used by the GUI thread to synchronize the shutdown
-  after shouldExit has been set to true.
- */
-
-
-void QQuickRenderThreadSingleContextWindowManager::initialize()
-{
-    Q_ASSERT(m_rendered_windows.size());
-
-    QQuickWindow *win = 0;
-    for (QHash<QQuickWindow *, WindowData *>::const_iterator it = m_rendered_windows.constBegin();
-        it != m_rendered_windows.constEnd() && !win; ++it) {
-        if (QQuickWindowPrivate::get(it.key())->isRenderable())
-            win = it.key();
-    }
-    if (!win)
-        return;
-
-    gl = new QOpenGLContext();
-    // Pick up the surface format from one of them
-    gl->setFormat(win->requestedFormat());
-    gl->create();
-    if (!gl->makeCurrent(win))
-        qWarning("QQuickWindow: makeCurrent() failed...");
-
-    Q_ASSERT(!sg->isReady());
-    sg->initialize(gl);
-}
-
-
-/*!
-    This function is called when the window is created to register the window with
-    the window manager.
-
-    Called on GUI Thread.
- */
-
-void QQuickRenderThreadSingleContextWindowManager::show(QQuickWindow *window)
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: Window added to windowing system, %p, %dx%d\n", window, window->width(), window->height());
-#endif
-
-    WindowTracker tracker;
-    tracker.window = window;
-    tracker.isVisible = false;
-    tracker.toBeRemoved = false;
-    m_tracked_windows << tracker;
-
-    connect(window, SIGNAL(widthChanged(int)), this, SLOT(windowVisibilityChanged()), Qt::DirectConnection);
-    connect(window, SIGNAL(heightChanged(int)), this, SLOT(windowVisibilityChanged()), Qt::DirectConnection);
-
-    windowVisibilityChanged();
-}
-
-
-void QQuickRenderThreadSingleContextWindowManager::handleAddedWindow(QQuickWindow *window)
-{
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: adding window: %p\n", window);
-#endif
-
-    WindowData *data = new WindowData;
-    data->sizeWasChanged = false;
-    data->windowSize = window->size();
-    data->isVisible = window->isVisible();
-    data->isRenderable = QQuickWindowPrivate::get(window)->isRenderable();
-    m_rendered_windows[window] = data;
-
-    isExternalUpdatePending = true;
-}
-
-
-/*!
-    Called on Render Thread
- */
-void QQuickRenderThreadSingleContextWindowManager::handleAddedWindows()
-{
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: about to add %d\n", m_added_windows.size());
-#endif
-
-    while (m_added_windows.size()) {
-        QQuickWindow *window = m_added_windows.takeLast();
-        handleAddedWindow(window);
-    }
-}
-
-
-/*!
-    Called on the GUI Thread, from the window' destructor
- */
-
-void QQuickRenderThreadSingleContextWindowManager::windowDestroyed(QQuickWindow *window)
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: Window destroyed: %p\n", window);
-#endif
-
-    hide(window);
-}
-
-
-/*!
-    Called on GUI Thread
- */
-
-void QQuickRenderThreadSingleContextWindowManager::hide(QQuickWindow *window)
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: Window hidden: %p\n", window);
-#endif
-
-    int position = -1;
-    for (int i=0; i<m_tracked_windows.size(); ++i) {
-        if (m_tracked_windows.at(i).window == window) {
-            m_tracked_windows[i].toBeRemoved = true;
-            position = i;
-            break;
-        }
-    }
-
-    if (position >= 0) {
-        disconnect(window, SIGNAL(widthChanged(int)), this, SLOT(windowVisibilityChanged()));
-        disconnect(window, SIGNAL(heightChanged(int)), this, SLOT(windowVisibilityChanged()));
-        windowVisibilityChanged();
-        m_tracked_windows.removeAt(position);
-    }
-
-#ifdef THREAD_DEBUG
-    printf("GUI: Window removal completed... %p\n", window);
-#endif
-}
-
-/*!
-    Called on Render Thread
- */
-void QQuickRenderThreadSingleContextWindowManager::handleRemovedWindows(bool clearGLContext)
-{
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: about to remove %d\n", m_removed_windows.size());
-#endif
-
-    bool removedAnything = false;
-    while (m_removed_windows.size()) {
-        QQuickWindow *window = m_removed_windows.takeLast();
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: removing %p\n", window);
-#endif
-
-        QQuickWindowPrivate::get(window)->cleanupNodesOnShutdown();
-        delete m_rendered_windows.take(window);
-        removedAnything = true;
-    }
-
-    // If a window is removed because it has been hidden it will take with it
-    // the gl context (at least on Mac) if bound, so disconnect the gl context
-    // from anything
-    if (removedAnything && clearGLContext)
-        gl->doneCurrent();
-}
-
-
-
-/*!
-    Called on GUI Thread
- */
-
-void QQuickRenderThreadSingleContextWindowManager::windowVisibilityChanged()
-{
-    bool anyoneShowing = false;
-    QList<QQuickWindow *> toAdd, toRemove;
-
-    // Not optimal, but also not frequently used...
-    for (int i=0; i<m_tracked_windows.size(); ++i) {
-        WindowTracker &t = const_cast<WindowTracker &>(m_tracked_windows.at(i));
-        QQuickWindow *win = t.window;
-
-        Q_ASSERT(win->isVisible() || QQuickWindowPrivate::get(win)->renderWithoutShowing || t.toBeRemoved);
-        bool windowVisible = win->width() > 0 && win->height() > 0;
-        anyoneShowing |= (windowVisible && !t.toBeRemoved);
-
-        if ((!windowVisible && t.isVisible) || t.toBeRemoved) {
-            toRemove << win;
-        } else if (windowVisible && !t.isVisible) {
-            toAdd << win;
-        }
-        t.isVisible = windowVisible;
-    }
-
-    if (isRunning()) {
-        if (!anyoneShowing) {
-            stopRendering();
-        } else {
-            lockInGui();
-            exhaustSyncEvent();
-            m_added_windows << toAdd;
-            m_removed_windows << toRemove;
-            while (isRunning() && (m_added_windows.size() || m_removed_windows.size())) {
-                if (isRenderBlocked)
-                    wake();
-                wait();
-            }
-            unlockInGui();
-        }
-
-    } else if (anyoneShowing) {
-        Q_ASSERT(toRemove.isEmpty()); // since loop is not running, nothing is showing now
-        for (int i=0; i<toAdd.size(); ++i)
-            handleAddedWindow(toAdd.at(i));
-        startRendering();
-    }
-
-}
-
-
-void QQuickRenderThreadSingleContextWindowManager::run()
-{
-#ifdef THREAD_DEBUG
-    printf("QML Rendering Thread Started\n");
-#endif
-
-    lock();
-    Q_ASSERT(!gl);
-    initialize();
-    // Wake GUI as it is waiting for the GL context to have appeared, as
-    // an indication that the render thread is now running.
-    wake();
-    unlock();
-
-    if (!gl)
-        return;
-
-    while (!shouldExit) {
-        lock();
-
-#ifdef THREAD_DEBUG
-        printf("                RenderThread: *** NEW FRAME ***\n");
-#endif
-
-        isExternalUpdatePending = false;
-        handleAddedWindows();
-
-        if (!isGuiLocked) {
-            isPostingSyncEvent = true;
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: acquired sync lock...\n");
-#endif
-            QCoreApplication::postEvent(this, new QEvent(QEvent_Sync));
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: going to sleep...\n");
-#endif
-            wake(); // In case the event got through all the way to wait() before this thread got to wait.
-            wait();
-
-
-            isPostingSyncEvent = false;
-        }
-
-#ifdef THREAD_DEBUG
-        printf("                RenderThread: Doing locked sync\n");
-#endif
-#ifdef QQUICK_RENDER_TIMING
-        if (qquick_render_timing())
-            threadTimer.start();
-#endif
-        inSync = true;
-        for (QHash<QQuickWindow *, WindowData *>::const_iterator it = m_rendered_windows.constBegin();
-             it != m_rendered_windows.constEnd(); ++it) {
-            QQuickWindow *window = it.key();
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: Syncing window: %p\n", window);
-#endif
-
-            WindowData *windowData = it.value();
-            QQuickWindowPrivate *windowPrivate = QQuickWindowPrivate::get(window);
-
-            windowData->isRenderable = windowPrivate->isRenderable();
-
-            if (windowData->isRenderable) {
-                gl->makeCurrent(window);
-
-                if (windowData->viewportSize != windowData->windowSize) {
-#ifdef THREAD_DEBUG
-                    printf("                RenderThread: --- window has changed size...\n");
-#endif
-                    windowData->viewportSize = windowData->windowSize;
-                    windowData->sizeWasChanged = true;
-                    glViewport(0, 0, windowData->viewportSize.width(), windowData->viewportSize.height());
-                }
-
-                windowPrivate->syncSceneGraph();
-            }
-        }
-        inSync = false;
-
-        // Wake GUI after sync to let it continue animating and event processing.
-        wake();
-        unlock();
-#ifdef THREAD_DEBUG
-        printf("                RenderThread: sync done\n");
-#endif
-#ifdef QQUICK_RENDER_TIMING
-        if (qquick_render_timing())
-            syncTime = threadTimer.elapsed();
-#endif
-
-        for (QHash<QQuickWindow *, WindowData *>::const_iterator it = m_rendered_windows.constBegin();
-             it != m_rendered_windows.constEnd(); ++it) {
-            QQuickWindow *window = it.key();
-            WindowData *windowData = it.value();
-            QQuickWindowPrivate *windowPrivate = QQuickWindowPrivate::get(window);
-
-            if (!windowData->isRenderable)
-                continue;
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: Rendering window %p\n", window);
-#endif
-
-            Q_ASSERT(windowData->windowSize.width() > 0 && windowData->windowSize.height() > 0);
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: --- rendering at size %dx%d\n",
-                   windowData->viewportSize.width(), windowData->viewportSize.height()
-                   );
-#endif
-
-            // We only need to re-makeCurrent when we have multiple surfaces.
-            if (m_rendered_windows.size() > 1)
-                gl->makeCurrent(window);
-
-            windowPrivate->renderSceneGraph(windowData->viewportSize);
-#ifdef QQUICK_RENDER_TIMING
-            if (qquick_render_timing())
-                renderTime = threadTimer.elapsed() - syncTime;
-#endif
-
-            // The content of the target buffer is undefined after swap() so grab needs
-            // to happen before swap();
-            if (window == windowToGrab) {
-#ifdef THREAD_DEBUG
-                printf("                RenderThread: --- grabbing...\n");
-#endif
-                grabContent = qt_gl_read_framebuffer(windowData->windowSize, false, false);
-                windowToGrab = 0;
-            }
-
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: --- wait for swap...\n");
-#endif
-
-            if (windowData->isVisible && window->isExposed())
-                gl->swapBuffers(window);
-
-            windowPrivate->fireFrameSwapped();
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: --- swap complete...\n");
-#endif
-
-        }
-
-#ifdef QQUICK_RENDER_TIMING
-            if (qquick_render_timing()) {
-                static QTime lastFrameTime = QTime::currentTime();
-                swapTime = threadTimer.elapsed() - renderTime - syncTime;
-                qDebug() << "- Breakdown of frame time; sync:" << syncTime
-                         << "ms render:" << renderTime << "ms swap:" << swapTime
-                         << "ms total:" << swapTime + renderTime + syncTime
-                         << "ms time since last frame:" << (lastFrameTime.msecsTo(QTime::currentTime()))
-                         << "ms";
-                lastFrameTime = QTime::currentTime();
-            }
-#endif
-
-        lock();
-
-        handleRemovedWindows();
-
-        // Update sizes...
-        for (QHash<QQuickWindow *, WindowData *>::const_iterator it = m_rendered_windows.constBegin();
-             it != m_rendered_windows.constEnd(); ++it) {
-            WindowData *windowData = it.value();
-            if (windowData->sizeWasChanged) {
-                windowData->renderedSize = windowData->viewportSize;
-                windowData->sizeWasChanged = false;
-            }
-        }
-
-
-        // Wake the GUI thread now that rendering is complete, to signal that painting
-        // is done, resizing is done or grabbing is completed. For grabbing, we're
-        // signalling this much later than needed (we could have done it before swap)
-        // but we don't want to lock an extra time.
-        wake();
-
-        if (!animationRunning && !isExternalUpdatePending && !shouldExit && !windowToGrab) {
-#ifdef THREAD_DEBUG
-            printf("                RenderThread: nothing to do, going to sleep...\n");
-#endif
-            isRenderBlocked = true;
-            wait();
-            isRenderBlocked = false;
-        }
-
-        unlock();
-
-        QCoreApplication::processEvents();
-
-        // Process any "deleteLater" objects...
-        QCoreApplication::sendPostedEvents(0, QEvent::DeferredDelete);
-    }
-
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: deleting all outstanding nodes\n");
-#endif
-
-    m_removed_windows << m_rendered_windows.keys();
-    handleRemovedWindows(false);
-
-    sg->invalidate();
-
-    gl->doneCurrent();
-    delete gl;
-    gl = 0;
-
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: render loop exited... Good Night!\n");
-#endif
-
-    lock();
-    hasExited = true;
-
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: waking GUI for final sleep..\n");
-#endif
-    wake();
-    unlock();
-
-#ifdef THREAD_DEBUG
-    printf("                RenderThread: All done...\n");
-#endif
-}
-
-bool QQuickRenderThreadSingleContextWindowManager::event(QEvent *e)
-{
-    Q_ASSERT(QThread::currentThread() == qApp->thread());
-
-    if (e->type() == QEvent_Sync) {
-
-        // If all windowes have been hidden, ignore the event
-        if (!isRunning())
-            return true;
-
-        if (!syncAlreadyHappened)
-            sync(false);
-
-        syncAlreadyHappened = false;
-
-        if (animationRunning) {
-#ifdef THREAD_DEBUG
-            printf("GUI: Advancing animations...\n");
-#endif
-
-            animDriver->advance();
-
-#ifdef THREAD_DEBUG
-            printf("GUI: Animations advanced...\n");
-#endif
-        }
-
-        return true;
-    } else if (e->type() == QEvent_DeferredUpdate) {
-        handleDeferredUpdate();
-
-    } else if (e->type() == QEvent::Timer) {
-#ifdef THREAD_DEBUG
-            printf("GUI: Animations advanced via timer...\n");
-#endif
-        animDriver->advance();
-    }
-
-    return QThread::event(e);
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::exhaustSyncEvent()
-{
-    if (isPostingSyncEvent) {
-        sync(true);
-        syncAlreadyHappened = true;
-    }
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::sync(bool guiAlreadyLocked)
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: sync - %s\n", guiAlreadyLocked ? "outside event" : "inside event");
-#endif
-    if (!guiAlreadyLocked)
-        lockInGui();
-
-    for (QHash<QQuickWindow *, WindowData *>::const_iterator it = m_rendered_windows.constBegin();
-         it != m_rendered_windows.constEnd(); ++it) {
-        QQuickWindowPrivate::get(it.key())->polishItems();
-    }
-
-    wake();
-    wait();
-
-    if (!guiAlreadyLocked)
-        unlockInGui();
-}
-
-
-
-
-/*!
-    Acquires the mutex for the GUI thread. The function uses the isGuiLocked
-    variable to keep track of how many recursion levels the gui is locked with.
-    We only actually acquire the mutex for the first level to avoid deadlocking
-    ourselves.
- */
-
-void QQuickRenderThreadSingleContextWindowManager::lockInGui()
-{
-    if (++isGuiLocked == 1)
-        lock();
-
-#ifdef THREAD_DEBUG
-    printf("GUI: acquired lock... level=%d\n", isGuiLocked);
-#endif
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::unlockInGui()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: releasing lock... level=%d\n", isGuiLocked);
-#endif
-
-    if (--isGuiLocked == 0)
-        unlock();
-}
-
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::animationStarted()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: animationStarted()\n");
-#endif
-
-    if (!isRunning()) {
-        animationTimer = startTimer(1000/60);
-        return;
-    }
-
-    lockInGui();
-
-    animationRunning = true;
-
-    if (isRenderBlocked)
-        wake();
-
-    unlockInGui();
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::animationStopped()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: animationStopped()...\n");
-#endif
-
-    if (!isRunning()) {
-        killTimer(animationTimer);
-        animationTimer = -1;
-        return;
-    }
-
-    lockInGui();
-    animationRunning = false;
-    unlockInGui();
-}
-
-
-void QQuickRenderThreadSingleContextWindowManager::exposureChanged(QQuickWindow *window)
-{
-    Q_UNUSED(window);
-#ifdef THREAD_DEBUG
-    printf("GUI: exposure changed: %p\n", window);
-#endif
-
-    if (window->isExposed())
-        maybeUpdate(window);
-
-#ifdef THREAD_DEBUG
-    printf("GUI: exposure changed done: %p\n", window);
-#endif
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::resize(QQuickWindow *window, const QSize &size)
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: Resize Event: %p = %dx%d\n", window, size.width(), size.height());
-#endif
-
-    // If the rendering thread is not running we do not need to do anything.
-    // Also if the window is being resized to an invalid size, it will be removed
-    // by the windowVisibilityChanged slot as result of width/heightcChanged()
-    if (!isRunning() || size.width() <= 0 || size.height() <= 0)
-        return;
-
-    lockInGui();
-    exhaustSyncEvent();
-
-    WindowData *windowData = m_rendered_windows.value(window);
-    if (windowData) {
-        windowData->windowSize = size;
-        while (isRunning() && windowData->renderedSize != size && size.width() > 0 && size.height() > 0) {
-            if (isRenderBlocked)
-                wake();
-            wait();
-        }
-    }
-    unlockInGui();
-
-#ifdef THREAD_DEBUG
-    printf("GUI: Resize done: %p\n", window);
-#endif
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::startRendering()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: Starting Render Thread\n");
-#endif
-    hasExited = false;
-    shouldExit = false;
-    isGuiLocked = 0;
-    isPostingSyncEvent = false;
-    syncAlreadyHappened = false;
-    inSync = false;
-
-    lockInGui();
-    animationRunning = animDriver->isRunning();
-    start(); // Start the render thread...
-    wait();
-    unlockInGui();
-
-    // Animations will now be driven from the rendering thread.
-    if (animationTimer >= 0) {
-        killTimer(animationTimer);
-        animationTimer = -1;
-    }
-
-
-}
-
-
-
-void QQuickRenderThreadSingleContextWindowManager::stopRendering()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: stopping render thread\n");
-#endif
-
-    lockInGui();
-    exhaustSyncEvent();
-    shouldExit = true;
-
-    if (isRenderBlocked) {
-#ifdef THREAD_DEBUG
-        printf("GUI: waking up render thread\n");
-#endif
-        wake();
-    }
-
-    while (!hasExited) {
-#ifdef THREAD_DEBUG
-        printf("GUI: waiting for render thread to have exited..\n");
-#endif
-        wait();
-    }
-
-    unlockInGui();
-
-#ifdef THREAD_DEBUG
-    printf("GUI: waiting for render thread to terminate..\n");
-#endif
-    // Actually wait for the thread to terminate.  Otherwise we can delete it
-    // too early and crash.
-    QThread::wait();
-
-#ifdef THREAD_DEBUG
-    printf("GUI: thread has terminated and we're all good..\n");
-#endif
-
-    // Activate timer to keep animations running
-    if (animDriver->isRunning())
-        animationTimer = startTimer(1000/60);
-}
-
-
-
-QImage QQuickRenderThreadSingleContextWindowManager::grab(QQuickWindow *window)
-{
-    if (!isRunning())
-        return QImage();
-
-    if (QThread::currentThread() != qApp->thread()) {
-        qWarning("QQuickWindow::grabFrameBuffer: can only be called from the GUI thread");
-        return QImage();
-    } else if (window->size().width() <= 0 || window->size().height() <= 0 ) {
-        qWarning("QQuickWindow::grabFrameBuffer: Can't grab a Window with size %dx%d", window->size().width(), window->size().height());
-        return QImage();
-    }
-
-#ifdef THREAD_DEBUG
-    printf("GUI: doing a pixelwise grab..\n");
-#endif
-
-    lockInGui();
-    exhaustSyncEvent();
-
-    windowToGrab = window;
-    while (isRunning() && windowToGrab) {
-        if (isRenderBlocked)
-            wake();
-        wait();
-    }
-
-    QImage grabbed = grabContent;
-    grabContent = QImage();
-
-    unlockInGui();
-
-    return grabbed;
-}
-
-
-void QQuickRenderThreadSingleContextWindowManager::handleDeferredUpdate()
-{
-#ifdef THREAD_DEBUG
-    printf("GUI: handling update to ourselves...\n");
-#endif
-
-    isDeferredUpdatePosted = false;
-
-    lockInGui();
-    isExternalUpdatePending = true;
-    if (isRenderBlocked)
-        wake();
-    unlockInGui();
-}
-
-void QQuickRenderThreadSingleContextWindowManager::maybeUpdate(QQuickWindow *)
-{
-    Q_ASSERT_X(QThread::currentThread() == QCoreApplication::instance()->thread() || inSync,
-               "QQuickWindow::update",
-               "Function can only be called from GUI thread or during QQuickItem::updatePaintNode()");
-
-    if (inSync) {
-        isExternalUpdatePending = true;
-
-    } else if (!isDeferredUpdatePosted) {
-#ifdef THREAD_DEBUG
-        printf("GUI: posting update to ourselves...\n");
-#endif
-        isDeferredUpdatePosted = true;
-        QCoreApplication::postEvent(this, new QEvent(QEvent_DeferredUpdate));
-    }
-
-}
-
-QT_END_NAMESPACE
diff --git a/src/quick/items/qquickthreadedwindowmanager_p.h b/src/quick/items/qquickthreadedwindowmanager_p.h
deleted file mode 100644
index 76325e2d4f..0000000000
--- a/src/quick/items/qquickthreadedwindowmanager_p.h
+++ /dev/null
@@ -1,181 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/legal
-**
-** This file is part of the QtQml module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and Digia.  For licensing terms and
-** conditions see http://qt.digia.com/licensing.  For further information
-** use the contact form at http://qt.digia.com/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 2.1 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU Lesser General Public License version 2.1 requirements
-** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
-**
-** In addition, as a special exception, Digia gives you certain additional
-** rights.  These rights are described in the Digia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3.0 as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU General Public License version 3.0 requirements will be
-** met: http://www.gnu.org/copyleft/gpl.html.
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QQUICKTHREADEDWINDOWMANAGER_P_H
-#define QQUICKTHREADEDWINDOWMANAGER_P_H
-
-#include "qquickwindowmanager_p.h"
-
-#include <QtCore/QCoreApplication>
-#include <QtCore/QMutex>
-#include <QtCore/QWaitCondition>
-#include <QtCore/private/qabstractanimation_p.h>
-
-#include <QtGui/QOpenGLContext>
-#include <QtQuick/private/qsgcontext_p.h>
-#include <private/qtquickglobal_p.h>
-
-QT_BEGIN_NAMESPACE
-
-class QQuickRenderThreadSingleContextWindowManager : public QThread, public QQuickWindowManager
-{
-    Q_OBJECT
-public:
-    QQuickRenderThreadSingleContextWindowManager()
-        : sg(QSGContext::createDefaultContext())
-        , gl(0)
-        , animationTimer(-1)
-        , isGuiLocked(0)
-        , animationRunning(false)
-        , isPostingSyncEvent(false)
-        , isRenderBlocked(false)
-        , isExternalUpdatePending(false)
-        , syncAlreadyHappened(false)
-        , inSync(false)
-        , shouldExit(false)
-        , hasExited(false)
-        , isDeferredUpdatePosted(false)
-        , windowToGrab(0)
-    {
-        sg->moveToThread(this);
-
-        animDriver = sg->createAnimationDriver(this);
-        animDriver->install();
-        connect(animDriver, SIGNAL(started()), this, SLOT(animationStarted()));
-        connect(animDriver, SIGNAL(stopped()), this, SLOT(animationStopped()));
-    }
-
-    QSGContext *sceneGraphContext() const { return sg; }
-
-    void releaseResources() { }
-
-    void show(QQuickWindow *window);
-    void hide(QQuickWindow *window);
-
-    void windowDestroyed(QQuickWindow *window);
-
-    void exposureChanged(QQuickWindow *window);
-    QImage grab(QQuickWindow *window);
-    void resize(QQuickWindow *window, const QSize &size);
-    void handleDeferredUpdate();
-    void maybeUpdate(QQuickWindow *window);
-    void update(QQuickWindow *window) { maybeUpdate(window); } // identical for this implementation
-
-    void startRendering();
-    void stopRendering();
-
-    void exhaustSyncEvent();
-    void sync(bool guiAlreadyLocked);
-
-    void initialize();
-
-    bool event(QEvent *);
-
-    inline void lock() { mutex.lock(); }
-    inline void unlock() { mutex.unlock(); }
-    inline void wait() { condition.wait(&mutex); }
-    inline void wake() { condition.wakeOne(); }
-    void lockInGui();
-    void unlockInGui();
-
-    void run();
-
-    QAnimationDriver *animationDriver() const { return animDriver; }
-
-public slots:
-    void animationStarted();
-    void animationStopped();
-    void windowVisibilityChanged();
-
-private:
-    void handleAddedWindows();
-    void handleAddedWindow(QQuickWindow *window);
-    void handleRemovedWindows(bool clearGLContext = true);
-
-    QSGContext *sg;
-    QOpenGLContext *gl;
-    QAnimationDriver *animDriver;
-    int animationTimer;
-
-    QMutex mutex;
-    QWaitCondition condition;
-
-    int isGuiLocked;
-    uint animationRunning: 1;
-    uint isPostingSyncEvent : 1;
-    uint isRenderBlocked : 1;
-    uint isExternalUpdatePending : 1;
-    uint syncAlreadyHappened : 1;
-    uint inSync : 1;
-    uint shouldExit : 1;
-    uint hasExited : 1;
-    uint isDeferredUpdatePosted : 1;
-
-    QQuickWindow *windowToGrab;
-    QImage grabContent;
-
-    struct WindowData {
-        QSize renderedSize;
-        QSize windowSize;
-        QSize viewportSize;
-
-        uint sizeWasChanged : 1;
-        uint isVisible : 1;
-        uint isRenderable : 1;
-    };
-
-    QHash<QQuickWindow *, WindowData *> m_rendered_windows;
-
-    struct WindowTracker {
-        QQuickWindow *window;
-        uint isVisible : 1;
-        uint toBeRemoved : 1;
-    };
-
-    QList<WindowTracker> m_tracked_windows;
-
-    QList<QQuickWindow *> m_removed_windows;
-    QList<QQuickWindow *> m_added_windows;
-};
-
-QT_END_NAMESPACE
-
-#endif // QQUICKTHREADEDWINDOWMANAGER_P_H
diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 1b76dd7390..bf82423ca9 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -50,7 +50,7 @@
 #include <QtQuick/private/qsgtexture_p.h>
 #include <QtQuick/private/qsgflashnode_p.h>
 
-#include <private/qquickwindowmanager_p.h>
+#include <private/qsgrenderloop_p.h>
 
 #include <private/qguiapplication_p.h>
 #include <QtGui/QInputMethod>
@@ -366,8 +366,8 @@ QQuickWindowPrivate::QQuickWindowPrivate()
     , windowManager(0)
     , clearColor(Qt::white)
     , clearBeforeRendering(true)
-    , persistentGLContext(false)
-    , persistentSceneGraph(false)
+    , persistentGLContext(true)
+    , persistentSceneGraph(true)
     , lastWheelEventAccepted(false)
     , renderTarget(0)
     , renderTargetId(0)
@@ -392,7 +392,7 @@ void QQuickWindowPrivate::init(QQuickWindow *c)
     contentItemPrivate->windowRefCount = 1;
     contentItemPrivate->flags |= QQuickItem::ItemIsFocusScope;
 
-    windowManager = QQuickWindowManager::instance();
+    windowManager = QSGRenderLoop::instance();
     context = windowManager->sceneGraphContext();
     q->setSurfaceType(QWindow::OpenGLSurface);
     q->setFormat(context->defaultSurfaceFormat());
@@ -923,6 +923,8 @@ QQuickWindow::QQuickWindow(QWindow *parent)
     d->init(this);
 }
 
+
+
 /*!
     \internal
 */
@@ -966,20 +968,32 @@ QQuickWindow::~QQuickWindow()
 void QQuickWindow::releaseResources()
 {
     Q_D(QQuickWindow);
-    d->windowManager->releaseResources();
+    d->windowManager->releaseResources(this);
     QQuickPixmap::purgeCache();
 }
 
 
 
 /*!
-    Sets whether the OpenGL context can be released as a part of a call to
-    releaseResources() to \a persistent.
+    Sets whether the OpenGL context can be released to \a
+    persistent. The default value is true.
+
+    The OpenGL context can be released to free up graphics resources
+    when the window is obscured, hidden or not rendering. When this
+    happens is implementation specific.
 
-    The OpenGL context might still be released when the user makes an explicit
-    call to hide().
+    The QOpenGLContext::aboutToBeDestroyed() signal is emitted from
+    the QQuickWindow::openglContext() when the OpenGL context is about
+    to be released.  The QQuickWindow::sceneGraphInitialized() signal
+    is emitted when a new OpenGL context is created for this
+    window. Make a Qt::DirectConnection to these signals to be
+    notified.
 
-    \sa setPersistentSceneGraph()
+    The OpenGL context is still released when the last QQuickWindow is
+    deleted.
+
+    \sa setPersistentSceneGraph(),
+    QOpenGLContext::aboutToBeDestroyed(), sceneGraphInitialized()
  */
 
 void QQuickWindow::setPersistentOpenGLContext(bool persistent)
@@ -989,9 +1003,13 @@ void QQuickWindow::setPersistentOpenGLContext(bool persistent)
 }
 
 
+
 /*!
-    Returns whether the OpenGL context can be released as a part of a call to
-    releaseResources().
+    Returns whether the OpenGL context can be released during the
+    lifetime of the QQuickWindow.
+
+    \note This is a hint. When and how this happens is implementation
+    specific.
  */
 
 bool QQuickWindow::isPersistentOpenGLContext() const
@@ -1003,13 +1021,24 @@ bool QQuickWindow::isPersistentOpenGLContext() const
 
 
 /*!
-    Sets whether the scene graph nodes and resources can be released as a
-    part of a call to releaseResources() to \a persistent.
+    Sets whether the scene graph nodes and resources can be released
+    to \a persistent.  The default value is true.
+
+    The scene graph nodes and resources can be released to free up
+    graphics resources when the window is obscured, hidden or not
+    rendering. When this happens is implementation specific.
 
-    The scene graph nodes and resources might still be released when the user
-    makes an explicit call to hide().
+    The QQuickWindow::sceneGraphInvalidated() signal is emitted when
+    cleanup occurs. The QQuickWindow::sceneGraphInitialized() signal
+    is emitted when a new scene graph is recreated for this
+    window. Make a Qt::DirectConnection to these signals to be
+    notified.
 
-    \sa setPersistentOpenGLContext()
+    The scene graph nodes and resources are still released when the
+    last QQuickWindow is deleted.
+
+    \sa setPersistentOpenGLContext(),
+    sceneGraphInvalidated(), sceneGraphInitialized()
  */
 
 void QQuickWindow::setPersistentSceneGraph(bool persistent)
@@ -1021,8 +1050,11 @@ void QQuickWindow::setPersistentSceneGraph(bool persistent)
 
 
 /*!
-    Returns whether the scene graph nodes and resources can be released as a part
-    of a call to releaseResources().
+    Returns whether the scene graph nodes and resources can be
+    released during the lifetime of this QQuickWindow.
+
+    \note This is a hint. When and how this happens is implementation
+    specific.
  */
 
 bool QQuickWindow::isPersistentSceneGraph() const
diff --git a/src/quick/items/qquickwindow_p.h b/src/quick/items/qquickwindow_p.h
index da2ae8284d..f272f30f8e 100644
--- a/src/quick/items/qquickwindow_p.h
+++ b/src/quick/items/qquickwindow_p.h
@@ -73,7 +73,7 @@ QT_BEGIN_NAMESPACE
 
 //Make it easy to identify and customize the root item if needed
 
-class QQuickWindowManager;
+class QSGRenderLoop;
 
 class QQuickRootItem : public QQuickItem
 {
@@ -200,7 +200,7 @@ public:
     QSGContext *context;
     QSGRenderer *renderer;
 
-    QQuickWindowManager *windowManager;
+    QSGRenderLoop *windowManager;
 
     QColor clearColor;
 
diff --git a/src/quick/items/qquickwindowmanager.cpp b/src/quick/items/qquickwindowmanager.cpp
deleted file mode 100644
index 69aa63c278..0000000000
--- a/src/quick/items/qquickwindowmanager.cpp
+++ /dev/null
@@ -1,363 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/legal
-**
-** This file is part of the QtQml module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and Digia.  For licensing terms and
-** conditions see http://qt.digia.com/licensing.  For further information
-** use the contact form at http://qt.digia.com/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 2.1 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU Lesser General Public License version 2.1 requirements
-** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
-**
-** In addition, as a special exception, Digia gives you certain additional
-** rights.  These rights are described in the Digia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3.0 as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU General Public License version 3.0 requirements will be
-** met: http://www.gnu.org/copyleft/gpl.html.
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "qquickwindowmanager_p.h"
-#include "qquickthreadedwindowmanager_p.h"
-
-#include <QtCore/QCoreApplication>
-#include <QtCore/QTime>
-#include <QtCore/private/qabstractanimation_p.h>
-
-#include <QtGui/QOpenGLContext>
-#include <QtGui/private/qguiapplication_p.h>
-#include <qpa/qplatformintegration.h>
-
-#include <QtQml/private/qqmlglobal_p.h>
-
-#include <QtQuick/QQuickWindow>
-#include <QtQuick/private/qquickwindow_p.h>
-#include <QtQuick/private/qsgcontext_p.h>
-
-QT_BEGIN_NAMESPACE
-
-DEFINE_BOOL_CONFIG_OPTION(qquick_render_timing, QML_RENDER_TIMING)
-
-extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha);
-
-/*!
-    expectations for this manager to work:
-     - one opengl context to render multiple windows
-     - OpenGL pipeline will not block for vsync in swap
-     - OpenGL pipeline will block based on a full buffer queue.
-     - Multiple screens can share the OpenGL context
-     - Animations are advanced for all windows once per swap
- */
-
-DEFINE_BOOL_CONFIG_OPTION(qmlNoThreadedRenderer, QML_BAD_GUI_RENDER_LOOP);
-DEFINE_BOOL_CONFIG_OPTION(qmlForceThreadedRenderer, QML_FORCE_THREADED_RENDERER); // Might trigger graphics driver threading bugs, use at own risk
-
-QQuickWindowManager *QQuickWindowManager::s_instance = 0;
-
-QQuickWindowManager::~QQuickWindowManager()
-{
-}
-
-class QQuickTrivialWindowManager : public QObject, public QQuickWindowManager
-{
-    Q_OBJECT
-public:
-    QQuickTrivialWindowManager();
-
-    void show(QQuickWindow *window);
-    void hide(QQuickWindow *window);
-
-    void windowDestroyed(QQuickWindow *window);
-
-    void initializeGL();
-    void renderWindow(QQuickWindow *window);
-    void exposureChanged(QQuickWindow *window);
-    QImage grab(QQuickWindow *window);
-    void resize(QQuickWindow *window, const QSize &size);
-
-    void maybeUpdate(QQuickWindow *window);
-    void update(QQuickWindow *window) { maybeUpdate(window); } // identical for this implementation.
-
-    void releaseResources() { }
-
-    QAnimationDriver *animationDriver() const { return 0; }
-
-    QSGContext *sceneGraphContext() const;
-
-    bool event(QEvent *);
-
-    struct WindowData {
-        bool updatePending : 1;
-        bool grabOnly : 1;
-    };
-
-    QHash<QQuickWindow *, WindowData> m_windows;
-
-    QOpenGLContext *gl;
-    QSGContext *sg;
-
-    QImage grabContent;
-
-    bool eventPending;
-};
-
-
-QQuickWindowManager *QQuickWindowManager::instance()
-{
-    if (!s_instance) {
-
-        s_instance = QSGContext::createWindowManager();
-
-        bool bufferQueuing = QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::BufferQueueingOpenGL);
-#ifdef Q_OS_WIN
-        bool fancy = false; // QTBUG-28037
-#else
-        bool fancy = QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::ThreadedOpenGL);
-#endif
-        if (qmlNoThreadedRenderer())
-            fancy = false;
-        else if (qmlForceThreadedRenderer())
-            fancy = true;
-
-        // Enable fixed animation steps...
-        QByteArray fixed = qgetenv("QML_FIXED_ANIMATION_STEP");
-        bool fixedAnimationSteps = bufferQueuing;
-        if (fixed == "no")
-            fixedAnimationSteps = false;
-        else if (fixed.length())
-            fixedAnimationSteps = true;
-        if (fixedAnimationSteps)
-            QUnifiedTimer::instance(true)->setConsistentTiming(true);
-
-        if (!s_instance) {
-            s_instance = fancy
-                    ? (QQuickWindowManager*) new QQuickRenderThreadSingleContextWindowManager
-                    : (QQuickWindowManager*) new QQuickTrivialWindowManager;
-        }
-    }
-    return s_instance;
-}
-
-void QQuickWindowManager::setInstance(QQuickWindowManager *instance)
-{
-    Q_ASSERT(!s_instance);
-    s_instance = instance;
-}
-
-QQuickTrivialWindowManager::QQuickTrivialWindowManager()
-    : gl(0)
-    , eventPending(false)
-{
-    sg = QSGContext::createDefaultContext();
-}
-
-
-void QQuickTrivialWindowManager::show(QQuickWindow *window)
-{
-    WindowData data;
-    data.updatePending = false;
-    data.grabOnly = false;
-    m_windows[window] = data;
-
-    maybeUpdate(window);
-}
-
-void QQuickTrivialWindowManager::hide(QQuickWindow *window)
-{
-    if (!m_windows.contains(window))
-        return;
-
-    m_windows.remove(window);
-    QQuickWindowPrivate *cd = QQuickWindowPrivate::get(window);
-    cd->cleanupNodesOnShutdown();
-
-    if (m_windows.size() == 0) {
-        sg->invalidate();
-        delete gl;
-        gl = 0;
-    }
-}
-
-void QQuickTrivialWindowManager::windowDestroyed(QQuickWindow *window)
-{
-    hide(window);
-}
-
-void QQuickTrivialWindowManager::renderWindow(QQuickWindow *window)
-{
-    bool renderWithoutShowing = QQuickWindowPrivate::get(window)->renderWithoutShowing;
-    if ((!window->isExposed() && !renderWithoutShowing) || !m_windows.contains(window))
-        return;
-
-    WindowData &data = const_cast<WindowData &>(m_windows[window]);
-
-    QQuickWindow *masterWindow = 0;
-    if (!window->isVisible() && !renderWithoutShowing) {
-        // Find a "proper surface" to bind...
-        for (QHash<QQuickWindow *, WindowData>::const_iterator it = m_windows.constBegin();
-             it != m_windows.constEnd() && !masterWindow; ++it) {
-            if (it.key()->isVisible())
-                masterWindow = it.key();
-        }
-    } else {
-        masterWindow = window;
-    }
-
-    if (!masterWindow)
-        return;
-
-    if (!QQuickWindowPrivate::get(masterWindow)->isRenderable()) {
-        qWarning().nospace()
-            << "Unable to find a renderable master window "
-            << masterWindow << "when trying to render"
-            << window << " (" << window->geometry() << ").";
-        return;
-    }
-
-    if (!gl) {
-        gl = new QOpenGLContext();
-        gl->setFormat(masterWindow->requestedFormat());
-        gl->create();
-        if (!gl->makeCurrent(masterWindow))
-            qWarning("QQuickWindow: makeCurrent() failed...");
-        sg->initialize(gl);
-    } else {
-        gl->makeCurrent(masterWindow);
-    }
-
-    bool alsoSwap = data.updatePending;
-    data.updatePending = false;
-
-    QQuickWindowPrivate *cd = QQuickWindowPrivate::get(window);
-    cd->polishItems();
-
-    int renderTime = 0, syncTime = 0;
-    QTime renderTimer;
-    if (qquick_render_timing())
-        renderTimer.start();
-
-    cd->syncSceneGraph();
-
-    if (qquick_render_timing())
-        syncTime = renderTimer.elapsed();
-
-    cd->renderSceneGraph(window->size());
-
-    if (qquick_render_timing())
-        renderTime = renderTimer.elapsed() - syncTime;
-
-    if (data.grabOnly) {
-        grabContent = qt_gl_read_framebuffer(window->size(), false, false);
-        data.grabOnly = false;
-    }
-
-    if (alsoSwap && window->isVisible()) {
-        gl->swapBuffers(window);
-        cd->fireFrameSwapped();
-    }
-
-    if (qquick_render_timing()) {
-        static QTime lastFrameTime = QTime::currentTime();
-        const int swapTime = renderTimer.elapsed() - renderTime - syncTime;
-        qDebug() << "- Breakdown of frame time; sync:" << syncTime
-                 << "ms render:" << renderTime << "ms swap:" << swapTime
-                 << "ms total:" << swapTime + renderTime + syncTime
-                 << "ms time since last frame:" << (lastFrameTime.msecsTo(QTime::currentTime()))
-                 << "ms";
-        lastFrameTime = QTime::currentTime();
-    }
-
-    // Might have been set during syncSceneGraph()
-    if (data.updatePending)
-        maybeUpdate(window);
-}
-
-void QQuickTrivialWindowManager::exposureChanged(QQuickWindow *window)
-{
-    if (window->isExposed())
-        maybeUpdate(window);
-}
-
-QImage QQuickTrivialWindowManager::grab(QQuickWindow *window)
-{
-    if (!m_windows.contains(window))
-        return QImage();
-
-    m_windows[window].grabOnly = true;
-
-    renderWindow(window);
-
-    QImage grabbed = grabContent;
-    grabContent = QImage();
-    return grabbed;
-}
-
-
-
-void QQuickTrivialWindowManager::resize(QQuickWindow *, const QSize &)
-{
-}
-
-
-
-void QQuickTrivialWindowManager::maybeUpdate(QQuickWindow *window)
-{
-    if (!m_windows.contains(window))
-        return;
-
-    m_windows[window].updatePending = true;
-
-    if (!eventPending) {
-        QCoreApplication::postEvent(this, new QEvent(QEvent::User));
-        eventPending = true;
-    }
-}
-
-
-
-QSGContext *QQuickTrivialWindowManager::sceneGraphContext() const
-{
-    return sg;
-}
-
-
-bool QQuickTrivialWindowManager::event(QEvent *e)
-{
-    if (e->type() == QEvent::User) {
-        eventPending = false;
-        for (QHash<QQuickWindow *, WindowData>::const_iterator it = m_windows.constBegin();
-             it != m_windows.constEnd(); ++it) {
-            const WindowData &data = it.value();
-            if (data.updatePending)
-                renderWindow(it.key());
-        }
-        return true;
-    }
-    return QObject::event(e);
-}
-
-#include "qquickwindowmanager.moc"
-
-QT_END_NAMESPACE
diff --git a/src/quick/items/qquickwindowmanager_p.h b/src/quick/items/qquickwindowmanager_p.h
deleted file mode 100644
index 94142a9d90..0000000000
--- a/src/quick/items/qquickwindowmanager_p.h
+++ /dev/null
@@ -1,87 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/legal
-**
-** This file is part of the QtQml module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and Digia.  For licensing terms and
-** conditions see http://qt.digia.com/licensing.  For further information
-** use the contact form at http://qt.digia.com/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 2.1 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU Lesser General Public License version 2.1 requirements
-** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
-**
-** In addition, as a special exception, Digia gives you certain additional
-** rights.  These rights are described in the Digia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3.0 as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL included in the
-** packaging of this file.  Please review the following information to
-** ensure the GNU General Public License version 3.0 requirements will be
-** met: http://www.gnu.org/copyleft/gpl.html.
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QQUICKWINDOWMANAGER_P_H
-#define QQUICKWINDOWMANAGER_P_H
-
-#include <QtGui/QImage>
-#include <private/qtquickglobal_p.h>
-
-QT_BEGIN_NAMESPACE
-
-class QQuickWindow;
-class QSGContext;
-class QAnimationDriver;
-
-class Q_QUICK_PRIVATE_EXPORT QQuickWindowManager
-{
-public:
-    virtual ~QQuickWindowManager();
-
-    virtual void show(QQuickWindow *window) = 0;
-    virtual void hide(QQuickWindow *window) = 0;
-
-    virtual void windowDestroyed(QQuickWindow *window) = 0;
-
-    virtual void exposureChanged(QQuickWindow *window) = 0;
-    virtual QImage grab(QQuickWindow *window) = 0;
-    virtual void resize(QQuickWindow *window, const QSize &size) = 0;
-
-    virtual void update(QQuickWindow *window) = 0;
-    virtual void maybeUpdate(QQuickWindow *window) = 0;
-
-    virtual QAnimationDriver *animationDriver() const = 0;
-
-    virtual QSGContext *sceneGraphContext() const = 0;
-
-    virtual void releaseResources() = 0;
-
-    // ### make this less of a singleton
-    static QQuickWindowManager *instance();
-    static void setInstance(QQuickWindowManager *instance);
-
-private:
-    static QQuickWindowManager *s_instance;
-};
-
-QT_END_NAMESPACE
-
-#endif // QQUICKWINDOWMANAGER_P_H