Add generic OpenGL compositor and backingstore bits

By removing the EGL(FS) dependencies we get classes that can be used
by any platform plugin that runs without a windowing system.

Change-Id: If99b42de5a4da02bbef80863609b6d92c6734613
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>

10 files changed, 32 insertions, 687 deletions

diff --git a/src/platformsupport/eglconvenience/eglconvenience.pri b/src/platformsupport/eglconvenience/eglconvenience.pri
index 8ada53d2c1..d102203d5e 100644
--- a/src/platformsupport/eglconvenience/eglconvenience.pri
+++ b/src/platformsupport/eglconvenience/eglconvenience.pri
@@ -16,16 +16,12 @@ contains(QT_CONFIG,egl) {
                 $$PWD/qeglplatformcursor_p.h \
                 $$PWD/qeglplatformwindow_p.h \
                 $$PWD/qeglplatformscreen_p.h \
-                $$PWD/qeglcompositor_p.h \
-                $$PWD/qeglplatformbackingstore_p.h \
                 $$PWD/qeglplatformintegration_p.h
 
             SOURCES += \
                 $$PWD/qeglplatformcursor.cpp \
                 $$PWD/qeglplatformwindow.cpp \
                 $$PWD/qeglplatformscreen.cpp \
-                $$PWD/qeglcompositor.cpp \
-                $$PWD/qeglplatformbackingstore.cpp \
                 $$PWD/qeglplatformintegration.cpp
         }
     }
diff --git a/src/platformsupport/eglconvenience/qeglcompositor.cpp b/src/platformsupport/eglconvenience/qeglcompositor.cpp
deleted file mode 100644
index 5866edc48d..0000000000
--- a/src/platformsupport/eglconvenience/qeglcompositor.cpp
+++ /dev/null
@@ -1,185 +0,0 @@
-/****************************************************************************
-**
-** 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.
-**
-** $QT_BEGIN_LICENSE:LGPL21$
-** 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 or version 3 as published by the Free
-** Software Foundation and appearing in the file LICENSE.LGPLv21 and
-** LICENSE.LGPLv3 included in the packaging of this file. Please review the
-** following information to ensure the GNU Lesser General Public License
-** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
-** 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.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include <QtGui/QOpenGLContext>
-#include <QtGui/QOpenGLShaderProgram>
-#include <QtGui/QOpenGLFramebufferObject>
-#include <QtGui/private/qopengltextureblitter_p.h>
-#include <qpa/qplatformbackingstore.h>
-
-#include "qeglcompositor_p.h"
-#include "qeglplatformwindow_p.h"
-#include "qeglplatformscreen_p.h"
-
-QT_BEGIN_NAMESPACE
-
-static QEGLCompositor *compositor = 0;
-
-QEGLCompositor::QEGLCompositor()
-    : m_context(0),
-      m_window(0),
-      m_blitter(0)
-{
-    Q_ASSERT(!compositor);
-    m_updateTimer.setSingleShot(true);
-    m_updateTimer.setInterval(0);
-    connect(&m_updateTimer, SIGNAL(timeout()), SLOT(renderAll()));
-}
-
-QEGLCompositor::~QEGLCompositor()
-{
-    Q_ASSERT(compositor == this);
-    if (m_blitter) {
-        m_blitter->destroy();
-        delete m_blitter;
-    }
-    compositor = 0;
-}
-
-void QEGLCompositor::schedule(QOpenGLContext *context, QEGLPlatformWindow *window)
-{
-    m_context = context;
-    m_window = window;
-    if (!m_updateTimer.isActive())
-        m_updateTimer.start();
-}
-
-void QEGLCompositor::renderAll()
-{
-    Q_ASSERT(m_context && m_window);
-    m_context->makeCurrent(m_window->window());
-
-    if (!m_blitter) {
-        m_blitter = new QOpenGLTextureBlitter;
-        m_blitter->create();
-    }
-    m_blitter->bind();
-
-    QEGLPlatformScreen *screen = static_cast<QEGLPlatformScreen *>(m_window->screen());
-    QList<QEGLPlatformWindow *> windows = screen->windows();
-    for (int i = 0; i < windows.size(); ++i)
-        render(windows.at(i));
-
-    m_blitter->release();
-    m_context->swapBuffers(m_window->window());
-
-    for (int i = 0; i < windows.size(); ++i)
-        windows.at(i)->composited();
-}
-
-struct BlendStateBinder
-{
-    BlendStateBinder() : m_blend(false) {
-        glDisable(GL_BLEND);
-    }
-    void set(bool blend) {
-        if (blend != m_blend) {
-            if (blend) {
-                glEnable(GL_BLEND);
-                glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-            } else {
-                glDisable(GL_BLEND);
-            }
-            m_blend = blend;
-        }
-    }
-    ~BlendStateBinder() {
-        if (m_blend)
-            glDisable(GL_BLEND);
-    }
-    bool m_blend;
-};
-
-void QEGLCompositor::render(QEGLPlatformWindow *window)
-{
-    const QPlatformTextureList *textures = window->textures();
-    if (!textures)
-        return;
-
-    const QRect targetWindowRect(QPoint(0, 0), window->screen()->geometry().size());
-    glViewport(0, 0, targetWindowRect.width(), targetWindowRect.height());
-
-    float currentOpacity = 1.0f;
-    BlendStateBinder blend;
-
-    for (int i = 0; i < textures->count(); ++i) {
-        uint textureId = textures->textureId(i);
-        QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(textures->geometry(i),
-                                                                   targetWindowRect);
-        const float opacity = window->window()->opacity();
-        if (opacity != currentOpacity) {
-            currentOpacity = opacity;
-            m_blitter->setOpacity(currentOpacity);
-        }
-
-        if (textures->count() > 1 && i == textures->count() - 1) {
-            // Backingstore for a widget with QOpenGLWidget subwidgets
-            blend.set(true);
-            m_blitter->blit(textureId, target, QOpenGLTextureBlitter::OriginTopLeft);
-        } else if (textures->count() == 1) {
-            // A regular QWidget window
-            const bool translucent = window->window()->requestedFormat().alphaBufferSize() > 0;
-            blend.set(translucent);
-            m_blitter->blit(textureId, target, QOpenGLTextureBlitter::OriginTopLeft);
-        } else if (!textures->stacksOnTop(i)) {
-            // Texture from an FBO belonging to a QOpenGLWidget
-            blend.set(false);
-            m_blitter->blit(textureId, target, QOpenGLTextureBlitter::OriginBottomLeft);
-        }
-    }
-
-    for (int i = 0; i < textures->count(); ++i) {
-        if (textures->stacksOnTop(i)) {
-            QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(textures->geometry(i), targetWindowRect);
-            blend.set(true);
-            m_blitter->blit(textures->textureId(i), target, QOpenGLTextureBlitter::OriginBottomLeft);
-        }
-    }
-
-    m_blitter->setOpacity(1.0f);
-}
-
-QEGLCompositor *QEGLCompositor::instance()
-{
-    if (!compositor)
-        compositor = new QEGLCompositor;
-    return compositor;
-}
-
-void QEGLCompositor::destroy()
-{
-    delete compositor;
-    compositor = 0;
-}
-
-QT_END_NAMESPACE
diff --git a/src/platformsupport/eglconvenience/qeglcompositor_p.h b/src/platformsupport/eglconvenience/qeglcompositor_p.h
deleted file mode 100644
index 1401fbdd55..0000000000
--- a/src/platformsupport/eglconvenience/qeglcompositor_p.h
+++ /dev/null
@@ -1,83 +0,0 @@
-/****************************************************************************
-**
-** 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.
-**
-** $QT_BEGIN_LICENSE:LGPL21$
-** 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 or version 3 as published by the Free
-** Software Foundation and appearing in the file LICENSE.LGPLv21 and
-** LICENSE.LGPLv3 included in the packaging of this file. Please review the
-** following information to ensure the GNU Lesser General Public License
-** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
-** 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.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QEGLCOMPOSITOR_H
-#define QEGLCOMPOSITOR_H
-
-//
-//  W A R N I N G
-//  -------------
-//
-// This file is not part of the Qt API.  It exists purely as an
-// implementation detail.  This header file may change from version to
-// version without notice, or even be removed.
-//
-// We mean it.
-//
-
-#include <QtCore/QTimer>
-
-QT_BEGIN_NAMESPACE
-
-class QOpenGLContext;
-class QOpenGLTextureBlitter;
-class QEGLPlatformWindow;
-
-class QEGLCompositor : public QObject
-{
-    Q_OBJECT
-
-public:
-    void schedule(QOpenGLContext *context, QEGLPlatformWindow *window);
-
-    static QEGLCompositor *instance();
-    static void destroy();
-
-private slots:
-    void renderAll();
-
-private:
-    QEGLCompositor();
-    ~QEGLCompositor();
-
-    void render(QEGLPlatformWindow *window);
-
-    QOpenGLContext *m_context;
-    QEGLPlatformWindow *m_window;
-    QTimer m_updateTimer;
-    QOpenGLTextureBlitter *m_blitter;
-};
-
-QT_END_NAMESPACE
-
-#endif // QEGLCOMPOSITOR_H
diff --git a/src/platformsupport/eglconvenience/qeglplatformbackingstore.cpp b/src/platformsupport/eglconvenience/qeglplatformbackingstore.cpp
deleted file mode 100644
index 43c18573f2..0000000000
--- a/src/platformsupport/eglconvenience/qeglplatformbackingstore.cpp
+++ /dev/null
@@ -1,241 +0,0 @@
-/****************************************************************************
-**
-** 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.
-**
-** $QT_BEGIN_LICENSE:LGPL21$
-** 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 or version 3 as published by the Free
-** Software Foundation and appearing in the file LICENSE.LGPLv21 and
-** LICENSE.LGPLv3 included in the packaging of this file. Please review the
-** following information to ensure the GNU Lesser General Public License
-** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
-** 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.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include <QtGui/QOpenGLShaderProgram>
-#include <QtGui/QOpenGLContext>
-#include <QtGui/QPainter>
-
-#include "qeglplatformbackingstore_p.h"
-#include "qeglcompositor_p.h"
-#include "qeglplatformwindow_p.h"
-#include "qeglplatformscreen_p.h"
-
-QT_BEGIN_NAMESPACE
-
-/*!
-    \class QEGLPlatformBackingStore
-    \brief A backing store implementation for EGL and GLES.
-    \since 5.2
-    \internal
-    \ingroup qpa
-
-    This implementation uploads raster-rendered widget windows into
-    textures and composites them onto a single native window using
-    QEGLCompositor. This means that multiple top-level widgets are
-    supported without creating actual native windows for each of them.
-
-    The class is ready to be used as-is, the default
-    QEGLPlatformIntegration::createPlatformBackingStore()
-    implementation creates an instance which is ready to be used
-    without further customization.
-
-    If QEGLCompositor is not suitable, this backing store
-    implementation can also be used without it. In this case a
-    subclass must reimplement composite() and schedule an update in
-    its custom compositor when this function is called. The textures
-    are accessible via QEGLPlatformWindow::texture().
-*/
-
-QEGLPlatformBackingStore::QEGLPlatformBackingStore(QWindow *window)
-    : QPlatformBackingStore(window),
-      m_window(static_cast<QEGLPlatformWindow *>(window->handle())),
-      m_bsTexture(0),
-      m_textures(new QPlatformTextureList),
-      m_lockedWidgetTextures(0)
-{
-    m_window->setBackingStore(this);
-}
-
-QEGLPlatformBackingStore::~QEGLPlatformBackingStore()
-{
-    delete m_textures;
-}
-
-QPaintDevice *QEGLPlatformBackingStore::paintDevice()
-{
-    return &m_image;
-}
-
-void QEGLPlatformBackingStore::updateTexture()
-{
-    if (!m_bsTexture) {
-        glGenTextures(1, &m_bsTexture);
-        glBindTexture(GL_TEXTURE_2D, m_bsTexture);
-        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
-        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
-        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_image.width(), m_image.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
-    } else {
-        glBindTexture(GL_TEXTURE_2D, m_bsTexture);
-    }
-
-    if (!m_dirty.isNull()) {
-        QRegion fixed;
-        QRect imageRect = m_image.rect();
-
-        foreach (const QRect &rect, m_dirty.rects()) {
-            // intersect with image rect to be sure
-            QRect r = imageRect & rect;
-
-            // if the rect is wide enough it's cheaper to just
-            // extend it instead of doing an image copy
-            if (r.width() >= imageRect.width() / 2) {
-                r.setX(0);
-                r.setWidth(imageRect.width());
-            }
-
-            fixed |= r;
-        }
-
-        foreach (const QRect &rect, fixed.rects()) {
-            // if the sub-rect is full-width we can pass the image data directly to
-            // OpenGL instead of copying, since there's no gap between scanlines
-            if (rect.width() == imageRect.width()) {
-                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
-                                m_image.constScanLine(rect.y()));
-            } else {
-                glTexSubImage2D(GL_TEXTURE_2D, 0, rect.x(), rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
-                    m_image.copy(rect).constBits());
-            }
-        }
-
-        m_dirty = QRegion();
-    }
-}
-
-void QEGLPlatformBackingStore::flush(QWindow *window, const QRegion &region, const QPoint &offset)
-{
-    // Called for ordinary raster windows. This is rare since RasterGLSurface
-    // support is claimed which leads to having all QWidget windows marked as
-    // RasterGLSurface instead of just Raster. These go through
-    // compositeAndFlush() instead of this function.
-
-    Q_UNUSED(region);
-    Q_UNUSED(offset);
-
-    QEGLPlatformScreen *screen = static_cast<QEGLPlatformScreen *>(m_window->screen());
-    QEGLPlatformWindow *dstWin = screen->compositingWindow();
-    if (!dstWin || !dstWin->isRaster())
-        return;
-
-    screen->compositingContext()->makeCurrent(dstWin->window());
-    updateTexture();
-    m_textures->clear();
-    m_textures->appendTexture(m_bsTexture, window->geometry());
-    composite(screen->compositingContext(), dstWin);
-}
-
-void QEGLPlatformBackingStore::composeAndFlush(QWindow *window, const QRegion &region, const QPoint &offset,
-                                               QPlatformTextureList *textures, QOpenGLContext *context,
-                                               bool translucentBackground)
-{
-    // QOpenGLWidget content provided as textures. The raster content should go on top.
-
-    Q_UNUSED(region);
-    Q_UNUSED(offset);
-    Q_UNUSED(context);
-    Q_UNUSED(translucentBackground);
-
-    QEGLPlatformScreen *screen = static_cast<QEGLPlatformScreen *>(m_window->screen());
-    QEGLPlatformWindow *dstWin = screen->compositingWindow();
-    if (!dstWin || !dstWin->isRaster())
-        return;
-
-    screen->compositingContext()->makeCurrent(dstWin->window());
-
-    m_textures->clear();
-    for (int i = 0; i < textures->count(); ++i)
-        m_textures->appendTexture(textures->textureId(i), textures->geometry(i), textures->stacksOnTop(i));
-
-    updateTexture();
-    m_textures->appendTexture(m_bsTexture, window->geometry());
-
-    textures->lock(true);
-    m_lockedWidgetTextures = textures;
-
-    composite(screen->compositingContext(), dstWin);
-}
-
-void QEGLPlatformBackingStore::composite(QOpenGLContext *context, QEGLPlatformWindow *window)
-{
-    QEGLCompositor::instance()->schedule(context, window);
-}
-
-void QEGLPlatformBackingStore::composited()
-{
-    if (m_lockedWidgetTextures) {
-        QPlatformTextureList *textureList = m_lockedWidgetTextures;
-        m_lockedWidgetTextures = 0; // may reenter so null before unlocking
-        textureList->lock(false);
-    }
-}
-
-void QEGLPlatformBackingStore::beginPaint(const QRegion &region)
-{
-    m_dirty |= region;
-
-    if (m_image.hasAlphaChannel()) {
-        QPainter p(&m_image);
-        p.setCompositionMode(QPainter::CompositionMode_Source);
-        foreach (const QRect &r, region.rects())
-            p.fillRect(r, Qt::transparent);
-    }
-}
-
-void QEGLPlatformBackingStore::resize(const QSize &size, const QRegion &staticContents)
-{
-    Q_UNUSED(staticContents);
-
-    QEGLPlatformScreen *screen = static_cast<QEGLPlatformScreen *>(m_window->screen());
-    QEGLPlatformWindow *dstWin = screen->compositingWindow();
-    if (!dstWin || (!dstWin->isRaster() && dstWin->window()->surfaceType() != QSurface::RasterGLSurface))
-        return;
-
-    m_image = QImage(size, QImage::Format_RGBA8888);
-
-    m_window->create();
-
-    screen->compositingContext()->makeCurrent(dstWin->window());
-    if (m_bsTexture) {
-        glDeleteTextures(1, &m_bsTexture);
-        m_bsTexture = 0;
-    }
-}
-
-QImage QEGLPlatformBackingStore::toImage() const
-{
-    return m_image;
-}
-
-QT_END_NAMESPACE
diff --git a/src/platformsupport/eglconvenience/qeglplatformbackingstore_p.h b/src/platformsupport/eglconvenience/qeglplatformbackingstore_p.h
deleted file mode 100644
index 502ca5a639..0000000000
--- a/src/platformsupport/eglconvenience/qeglplatformbackingstore_p.h
+++ /dev/null
@@ -1,96 +0,0 @@
-/****************************************************************************
-**
-** 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.
-**
-** $QT_BEGIN_LICENSE:LGPL21$
-** 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 or version 3 as published by the Free
-** Software Foundation and appearing in the file LICENSE.LGPLv21 and
-** LICENSE.LGPLv3 included in the packaging of this file. Please review the
-** following information to ensure the GNU Lesser General Public License
-** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
-** 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.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QEGLPLATFORMBACKINGSTORE_H
-#define QEGLPLATFORMBACKINGSTORE_H
-
-//
-//  W A R N I N G
-//  -------------
-//
-// This file is not part of the Qt API.  It exists purely as an
-// implementation detail.  This header file may change from version to
-// version without notice, or even be removed.
-//
-// We mean it.
-//
-
-#include <qpa/qplatformbackingstore.h>
-
-#include <QImage>
-#include <QRegion>
-
-QT_BEGIN_NAMESPACE
-
-class QOpenGLContext;
-class QPlatformTextureList;
-class QEGLPlatformWindow;
-
-class QEGLPlatformBackingStore : public QPlatformBackingStore
-{
-public:
-    QEGLPlatformBackingStore(QWindow *window);
-    ~QEGLPlatformBackingStore();
-
-    QPaintDevice *paintDevice() Q_DECL_OVERRIDE;
-
-    void beginPaint(const QRegion &region) Q_DECL_OVERRIDE;
-
-    void flush(QWindow *window, const QRegion &region, const QPoint &offset) Q_DECL_OVERRIDE;
-    void resize(const QSize &size, const QRegion &staticContents) Q_DECL_OVERRIDE;
-
-    QImage toImage() const Q_DECL_OVERRIDE;
-    void composeAndFlush(QWindow *window, const QRegion &region, const QPoint &offset,
-                         QPlatformTextureList *textures, QOpenGLContext *context,
-                         bool translucentBackground) Q_DECL_OVERRIDE;
-
-    const QPlatformTextureList *textures() const { return m_textures; }
-
-    virtual void composite(QOpenGLContext *context, QEGLPlatformWindow *window);
-
-    void composited();
-
-private:
-    void updateTexture();
-
-    QEGLPlatformWindow *m_window;
-    QImage m_image;
-    QRegion m_dirty;
-    uint m_bsTexture;
-    QPlatformTextureList *m_textures;
-    QPlatformTextureList *m_lockedWidgetTextures;
-};
-
-QT_END_NAMESPACE
-
-#endif // QEGLPLATFORMBACKINGSTORE_H
diff --git a/src/platformsupport/eglconvenience/qeglplatformintegration.cpp b/src/platformsupport/eglconvenience/qeglplatformintegration.cpp
index fea2ae2369..09011e6e58 100644
--- a/src/platformsupport/eglconvenience/qeglplatformintegration.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformintegration.cpp
@@ -43,6 +43,7 @@
 #include <QtPlatformSupport/private/qgenericunixservices_p.h>
 #include <QtPlatformSupport/private/qgenericunixeventdispatcher_p.h>
 #include <QtPlatformSupport/private/qfbvthandler_p.h>
+#include <QtPlatformSupport/private/qopenglcompositorbackingstore_p.h>
 
 #if !defined(QT_NO_EVDEV) && (!defined(Q_OS_ANDROID) || defined(Q_OS_ANDROID_NO_SDK))
 #include <QtPlatformSupport/private/qevdevmousemanager_p.h>
@@ -59,7 +60,6 @@
 #include "qeglplatformintegration_p.h"
 #include "qeglplatformcontext_p.h"
 #include "qeglplatformwindow_p.h"
-#include "qeglplatformbackingstore_p.h"
 #include "qeglplatformscreen_p.h"
 #include "qeglplatformcursor_p.h"
 
@@ -141,7 +141,9 @@ QPlatformFontDatabase *QEGLPlatformIntegration::fontDatabase() const
 
 QPlatformBackingStore *QEGLPlatformIntegration::createPlatformBackingStore(QWindow *window) const
 {
-    return new QEGLPlatformBackingStore(window);
+    QOpenGLCompositorBackingStore *bs = new QOpenGLCompositorBackingStore(window);
+    static_cast<QEGLPlatformWindow *>(window->handle())->setBackingStore(bs);
+    return bs;
 }
 
 QPlatformWindow *QEGLPlatformIntegration::createPlatformWindow(QWindow *window) const
@@ -156,10 +158,9 @@ QPlatformWindow *QEGLPlatformIntegration::createPlatformWindow(QWindow *window)
 
 QPlatformOpenGLContext *QEGLPlatformIntegration::createPlatformOpenGLContext(QOpenGLContext *context) const
 {
-    QEGLPlatformScreen *screen = static_cast<QEGLPlatformScreen *>(context->screen()->handle());
     // If there is a "root" window into which raster and QOpenGLWidget content is
     // composited, all other contexts must share with its context.
-    QOpenGLContext *compositingContext = screen ? screen->compositingContext() : 0;
+    QOpenGLContext *compositingContext = QOpenGLCompositor::instance()->context();
     QPlatformOpenGLContext *share = compositingContext ? compositingContext->handle() : context->shareHandle();
     QVariant nativeHandle = context->nativeHandle();
     QPlatformOpenGLContext *platformContext = createContext(context->format(),
diff --git a/src/platformsupport/eglconvenience/qeglplatformscreen.cpp b/src/platformsupport/eglconvenience/qeglplatformscreen.cpp
index fd577a48d7..fd9befb575 100644
--- a/src/platformsupport/eglconvenience/qeglplatformscreen.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformscreen.cpp
@@ -31,8 +31,8 @@
 **
 ****************************************************************************/
 
-#include "qeglcompositor_p.h"
 #include "qeglplatformscreen_p.h"
+#include <QtPlatformSupport/private/qopenglcompositor_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -42,19 +42,6 @@ QT_BEGIN_NAMESPACE
     \since 5.2
     \internal
     \ingroup qpa
-
-    This class provides a lightweight base for QPlatformScreen
-    implementations. It covers basic window stack management which is
-    necessary when compositing multiple raster (widget-based) windows
-    together into one single native surface.
-
-    Reimplementing the virtuals are essential when using
-    QEGLPlatformBackingStore. The context and the window returned from
-    these are the ones that are used when compositing the textures
-    generated from the raster (widget) based windows.
-
-    \note It is up to the QEGLPlatformWindow subclasses to use the
-    functions, like addWindow(), removeWindow(), etc., provided here.
  */
 
 QEGLPlatformScreen::QEGLPlatformScreen(EGLDisplay dpy)
@@ -64,39 +51,7 @@ QEGLPlatformScreen::QEGLPlatformScreen(EGLDisplay dpy)
 
 QEGLPlatformScreen::~QEGLPlatformScreen()
 {
-    QEGLCompositor::destroy();
-}
-
-void QEGLPlatformScreen::addWindow(QEGLPlatformWindow *window)
-{
-    if (!m_windows.contains(window)) {
-        m_windows.append(window);
-        topWindowChanged(window);
-    }
-}
-
-void QEGLPlatformScreen::removeWindow(QEGLPlatformWindow *window)
-{
-    m_windows.removeOne(window);
-    if (!m_windows.isEmpty())
-        topWindowChanged(m_windows.last());
-}
-
-void QEGLPlatformScreen::moveToTop(QEGLPlatformWindow *window)
-{
-    m_windows.removeOne(window);
-    m_windows.append(window);
-    topWindowChanged(window);
-}
-
-void QEGLPlatformScreen::changeWindowIndex(QEGLPlatformWindow *window, int newIdx)
-{
-    int idx = m_windows.indexOf(window);
-    if (idx != -1 && idx != newIdx) {
-        m_windows.move(idx, newIdx);
-        if (newIdx == m_windows.size() - 1)
-            topWindowChanged(m_windows.last());
-    }
+    QOpenGLCompositor::destroy();
 }
 
 QT_END_NAMESPACE
diff --git a/src/platformsupport/eglconvenience/qeglplatformscreen_p.h b/src/platformsupport/eglconvenience/qeglplatformscreen_p.h
index bb1d26d7d2..e9d3363a66 100644
--- a/src/platformsupport/eglconvenience/qeglplatformscreen_p.h
+++ b/src/platformsupport/eglconvenience/qeglplatformscreen_p.h
@@ -60,22 +60,9 @@ public:
     QEGLPlatformScreen(EGLDisplay dpy);
     ~QEGLPlatformScreen();
 
-    QList<QEGLPlatformWindow *> windows() const { return m_windows; }
-
-    void addWindow(QEGLPlatformWindow *window);
-    void removeWindow(QEGLPlatformWindow *window);
-    void moveToTop(QEGLPlatformWindow *window);
-    void changeWindowIndex(QEGLPlatformWindow *window, int newIdx);
-
-    virtual void topWindowChanged(QEGLPlatformWindow *window) { Q_UNUSED(window); }
-
     EGLDisplay display() const { return m_dpy; }
 
-    virtual QEGLPlatformWindow *compositingWindow() = 0;
-    virtual QOpenGLContext *compositingContext() = 0;
-
 private:
-    QList<QEGLPlatformWindow *> m_windows;
     EGLDisplay m_dpy;
 };
 
diff --git a/src/platformsupport/eglconvenience/qeglplatformwindow.cpp b/src/platformsupport/eglconvenience/qeglplatformwindow.cpp
index af4c907e85..5e5c879a22 100644
--- a/src/platformsupport/eglconvenience/qeglplatformwindow.cpp
+++ b/src/platformsupport/eglconvenience/qeglplatformwindow.cpp
@@ -32,9 +32,10 @@
 ****************************************************************************/
 
 #include <qpa/qwindowsysteminterface.h>
+#include <QtPlatformSupport/private/qopenglcompositor_p.h>
+#include <QtPlatformSupport/private/qopenglcompositorbackingstore_p.h>
 
 #include "qeglplatformwindow_p.h"
-#include "qeglplatformbackingstore_p.h"
 #include "qeglplatformscreen_p.h"
 
 QT_BEGIN_NAMESPACE
@@ -47,7 +48,7 @@ QT_BEGIN_NAMESPACE
     \ingroup qpa
 
     Lightweight class providing some basic platform window operations
-    and interfacing with QEGLPlatformBackingStore.
+    and interfacing with QOpenGLCompositorBackingStore.
 
     Almost no QPlatformWindow functions are implemented here. This is
     intentional because different platform plugins may use different
@@ -57,13 +58,15 @@ QT_BEGIN_NAMESPACE
     enforce anything for these functions.
 
     \note Subclasses are responsible for invoking this class'
-    implementation of create(). When using QEGLPlatformScreen, the
-    subclasses of this class are expected to utilize the window stack
-    management functions (addWindow() etc.) provided there.
+    implementation of create() and are expected to utilize the window
+    stack management functions (addWindow() etc.) in
+    QOpenGLCompositor.
  */
 
 QEGLPlatformWindow::QEGLPlatformWindow(QWindow *w)
     : QPlatformWindow(w),
+      m_backingStore(0),
+      m_raster(false),
       m_winId(0)
 {
 }
@@ -100,6 +103,11 @@ bool QEGLPlatformWindow::isRaster() const
     return m_raster || window()->surfaceType() == QSurface::RasterGLSurface;
 }
 
+QWindow *QEGLPlatformWindow::sourceWindow() const
+{
+    return window();
+}
+
 const QPlatformTextureList *QEGLPlatformWindow::textures() const
 {
     if (m_backingStore)
@@ -108,10 +116,10 @@ const QPlatformTextureList *QEGLPlatformWindow::textures() const
     return 0;
 }
 
-void QEGLPlatformWindow::composited()
+void QEGLPlatformWindow::endCompositing()
 {
     if (m_backingStore)
-        m_backingStore->composited();
+        m_backingStore->notifyComposited();
 }
 
 WId QEGLPlatformWindow::winId() const
diff --git a/src/platformsupport/eglconvenience/qeglplatformwindow_p.h b/src/platformsupport/eglconvenience/qeglplatformwindow_p.h
index 3a19301e5d..947f02aeb5 100644
--- a/src/platformsupport/eglconvenience/qeglplatformwindow_p.h
+++ b/src/platformsupport/eglconvenience/qeglplatformwindow_p.h
@@ -46,33 +46,36 @@
 //
 
 #include <qpa/qplatformwindow.h>
+#include <QtPlatformSupport/private/qopenglcompositor_p.h>
 #include <EGL/egl.h>
 
 QT_BEGIN_NAMESPACE
 
-class QEGLPlatformBackingStore;
+class QOpenGLCompositorBackingStore;
 class QPlatformTextureList;
 
-class QEGLPlatformWindow : public QPlatformWindow
+class QEGLPlatformWindow : public QPlatformWindow, public QOpenGLCompositorWindow
 {
 public:
     QEGLPlatformWindow(QWindow *w);
 
     virtual void create();
 
-    QEGLPlatformBackingStore *backingStore() { return m_backingStore; }
-    void setBackingStore(QEGLPlatformBackingStore *backingStore) { m_backingStore = backingStore; }
-    const QPlatformTextureList *textures() const;
-    void composited();
+    QOpenGLCompositorBackingStore *backingStore() { return m_backingStore; }
+    void setBackingStore(QOpenGLCompositorBackingStore *backingStore) { m_backingStore = backingStore; }
     bool isRaster() const;
 
+    QWindow *sourceWindow() const Q_DECL_OVERRIDE;
+    const QPlatformTextureList *textures() const Q_DECL_OVERRIDE;
+    void endCompositing() Q_DECL_OVERRIDE;
+
     WId winId() const Q_DECL_OVERRIDE;
     void setOpacity(qreal opacity) Q_DECL_OVERRIDE;
 
     virtual EGLNativeWindowType eglWindow() const = 0;
 
 private:
-    QEGLPlatformBackingStore *m_backingStore;
+    QOpenGLCompositorBackingStore *m_backingStore;
     bool m_raster;
     WId m_winId;
 };