Blackberry: Grab viewfinder frames from native window

Since the conversion from NV12 to RGB on the CPU does not scale
for larger photo/video resolutions, this patch uses a different
approach. It uses the low-level screen API to grab screenshots
of the native viewfinder window and provides them as QImage to
the QAbstractVideoSurface. Even for large resolutions this
is quite performant.

Change-Id: I59a7cbe6850b3b07575ea10026f3180cfd22e935
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>

src/plugins/blackberry/blackberry.pro

@@ -10,6 +10,7 @@ LIBS += -lscreen
 HEADERS += bbserviceplugin.h
 SOURCES += bbserviceplugin.cpp
 
+include(common/common.pri)
 include(camera/camera.pri)
 include(mediaplayer/mediaplayer.pri)
 

src/plugins/blackberry/camera/bbcamerasession.cpp

@@ -42,6 +42,7 @@
 
 #include "bbcameraorientationhandler.h"
 #include "bbcameraviewfindersettingscontrol.h"
+#include "windowgrabber.h"
 
 #include <QAbstractVideoSurface>
 #include <QBuffer>
@@ -123,10 +124,13 @@ BbCameraSession::BbCameraSession(QObject *parent)
     , m_videoState(QMediaRecorder::StoppedState)
     , m_videoStatus(QMediaRecorder::LoadedStatus)
     , m_handle(CAMERA_HANDLE_INVALID)
+    , m_windowGrabber(new WindowGrabber(this))
 {
     connect(this, SIGNAL(statusChanged(QCamera::Status)), SLOT(updateReadyForCapture()));
     connect(this, SIGNAL(captureModeChanged(QCamera::CaptureModes)), SLOT(updateReadyForCapture()));
     connect(m_orientationHandler, SIGNAL(orientationChanged(int)), SLOT(deviceOrientationChanged(int)));
+
+    connect(m_windowGrabber, SIGNAL(frameGrabbed(QImage)), SLOT(viewfinderFrameGrabbed(QImage)));
 }
 
 BbCameraSession::~BbCameraSession()
@@ -626,8 +630,15 @@ void BbCameraSession::applyVideoSettings()
 
     Q_ASSERT(viewfinderResolution.isValid());
 
+    const QByteArray windowId = QString().sprintf("qcamera_vf_%p", this).toLatin1();
+    m_windowGrabber->setWindowId(windowId);
+
+    const QByteArray windowGroupId = m_windowGrabber->windowGroupId();
+
     camera_error_t result = CAMERA_EOK;
     result = camera_set_videovf_property(m_handle,
+                                         CAMERA_IMGPROP_WIN_GROUPID, windowGroupId.data(),
+                                         CAMERA_IMGPROP_WIN_ID, windowId.data(),
                                          CAMERA_IMGPROP_WIDTH, viewfinderResolution.width(),
                                          CAMERA_IMGPROP_HEIGHT, viewfinderResolution.height(),
                                          CAMERA_IMGPROP_ROTATION, 360 - m_nativeCameraOrientation);
@@ -743,125 +754,6 @@ void BbCameraSession::setAudioSettings(const QAudioEncoderSettings &settings)
     m_audioEncoderSettings = settings;
 }
 
-static QImage convertFrameToImage(camera_buffer_t *buffer)
-{
-    if (buffer->frametype != CAMERA_FRAMETYPE_NV12)
-        return QImage();
-
-    const unsigned int width = buffer->framedesc.nv12.width;
-    const unsigned int height = buffer->framedesc.nv12.height;
-
-    /**
-     * Copying the data from the buffer into our own data array and working
-     * on this copy is actually faster than working on the buffer.
-     * Looks like we hit some cache misses here, since the stride inside the
-     * NV12 frame is really large (4096) in comparison to the actual image width (768)
-     */
-    const unsigned long long size = width*height + width*height/2;
-    unsigned char *data = new unsigned char[size];
-
-    unsigned char *source = buffer->framebuf;
-    unsigned char *dest = data;
-    for (uint row = 0; row < height; ++row) {
-        memcpy(dest, source, width);
-        source += buffer->framedesc.nv12.stride;
-        dest += width;
-    }
-
-    source = buffer->framebuf + buffer->framedesc.nv12.uv_offset;
-    for (uint row = 0; row < height/2; ++row) {
-        memcpy(dest, source, width);
-        source += buffer->framedesc.nv12.uv_stride;
-        dest += width;
-    }
-
-    QImage image(width, height, QImage::Format_RGB32);
-
-    unsigned char *dataPtr = data;
-    unsigned char *uvDataPtr = 0;
-    unsigned int uv_base_offset = width*height;
-    int yValue = 0;
-    int uValue = 0;
-    int vValue = 0;
-    int bValue = 0;
-    int gValue = 0;
-    int rValue = 0;
-    unsigned char *rowStart = 0;
-
-    unsigned char *imageDest = 0;
-    for (unsigned int y = 0; y < height; ++y) {
-        imageDest = const_cast<unsigned char*>(image.constScanLine(y));
-        rowStart = data + (uv_base_offset + (width*qFloor(y/2.0)));
-        for (unsigned int x = 0; x < width; ++x) {
-            uvDataPtr = rowStart + (qFloor(x/2)*2);
-
-            yValue = ((*dataPtr++) - 16) * 1.164;
-            uValue = ((*uvDataPtr++) - 128);
-            vValue = ((*uvDataPtr) - 128);
-
-            bValue = yValue + 2.018 * uValue;
-            gValue = yValue - 0.813 * vValue - 0.391 * uValue;
-            rValue = yValue + 1.596 * vValue;
-
-            *imageDest = qBound(0, bValue, 255);
-            imageDest++;
-            *imageDest = qBound(0, gValue, 255);
-            imageDest++;
-            *imageDest = qBound(0, rValue, 255);
-            imageDest++;
-            *imageDest = 255;
-            imageDest++;
-        }
-    }
-
-    delete [] data;
-
-    return image;
-}
-
-void BbCameraSession::handlePhotoViewFinderData(camera_buffer_t *buffer)
-{
-    QTransform transform;
-
-    transform.rotate(m_nativeCameraOrientation);
-
-    const QImage frame = convertFrameToImage(buffer).transformed(transform);
-
-    QMutexLocker locker(&m_surfaceMutex);
-    if (m_surface) {
-        if (frame.size() != m_surface->surfaceFormat().frameSize()) {
-            m_surface->stop();
-            m_surface->start(QVideoSurfaceFormat(frame.size(), QVideoFrame::Format_RGB32));
-        }
-
-        QVideoFrame videoFrame(frame);
-
-        m_surface->present(videoFrame);
-    }
-}
-
-
-void BbCameraSession::handleVideoViewFinderData(camera_buffer_t *buffer)
-{
-    QTransform transform;
-
-    transform.rotate(m_nativeCameraOrientation);
-
-    const QImage frame = convertFrameToImage(buffer).transformed(transform);
-
-    QMutexLocker locker(&m_surfaceMutex);
-    if (m_surface) {
-        if (frame.size() != m_surface->surfaceFormat().frameSize()) {
-            m_surface->stop();
-            m_surface->start(QVideoSurfaceFormat(frame.size(), QVideoFrame::Format_RGB32));
-        }
-
-        QVideoFrame videoFrame(frame);
-
-        m_surface->present(videoFrame);
-    }
-}
-
 void BbCameraSession::updateReadyForCapture()
 {
     emit readyForCaptureChanged(isReadyForCapture());
@@ -981,6 +873,27 @@ void BbCameraSession::handleCameraPowerUp()
     startViewFinder();
 }
 
+void BbCameraSession::viewfinderFrameGrabbed(const QImage &image)
+{
+    QTransform transform;
+
+    transform.rotate(m_nativeCameraOrientation);
+
+    const QImage frame = image.copy().transformed(transform);
+
+    QMutexLocker locker(&m_surfaceMutex);
+    if (m_surface) {
+        if (frame.size() != m_surface->surfaceFormat().frameSize()) {
+            m_surface->stop();
+            m_surface->start(QVideoSurfaceFormat(frame.size(), QVideoFrame::Format_ARGB32));
+        }
+
+        QVideoFrame videoFrame(frame);
+
+        m_surface->present(videoFrame);
+    }
+}
+
 bool BbCameraSession::openCamera()
 {
     if (m_handle != CAMERA_HANDLE_INVALID) // camera is already open
@@ -1047,22 +960,6 @@ void BbCameraSession::closeCamera()
     emit statusChanged(m_status);
 }
 
-static void photoViewFinderDataCallback(camera_handle_t handle, camera_buffer_t *buffer, void *context)
-{
-    Q_UNUSED(handle)
-
-    BbCameraSession *session = static_cast<BbCameraSession*>(context);
-    session->handlePhotoViewFinderData(buffer);
-}
-
-static void videoViewFinderDataCallback(camera_handle_t handle, camera_buffer_t *buffer, void *context)
-{
-    Q_UNUSED(handle)
-
-    BbCameraSession *session = static_cast<BbCameraSession*>(context);
-    session->handleVideoViewFinderData(buffer);
-}
-
 static void viewFinderStatusCallback(camera_handle_t handle, camera_devstatus_t status, uint16_t value, void *context)
 {
     Q_UNUSED(handle)
@@ -1084,10 +981,10 @@ bool BbCameraSession::startViewFinder()
     QSize viewfinderResolution;
     camera_error_t result = CAMERA_EOK;
     if (m_captureMode & QCamera::CaptureStillImage) {
-        result = camera_start_photo_viewfinder(m_handle, photoViewFinderDataCallback, viewFinderStatusCallback, this);
+        result = camera_start_photo_viewfinder(m_handle, 0, viewFinderStatusCallback, this);
         viewfinderResolution = currentViewfinderResolution(QCamera::CaptureStillImage);
     } else if (m_captureMode & QCamera::CaptureVideo) {
-        result = camera_start_video_viewfinder(m_handle, videoViewFinderDataCallback, viewFinderStatusCallback, this);
+        result = camera_start_video_viewfinder(m_handle, 0, viewFinderStatusCallback, this);
         viewfinderResolution = currentViewfinderResolution(QCamera::CaptureVideo);
     }
 
@@ -1125,7 +1022,7 @@ bool BbCameraSession::startViewFinder()
 
     m_surfaceMutex.lock();
     if (m_surface) {
-        const bool ok = m_surface->start(QVideoSurfaceFormat(rotatedSize, QVideoFrame::Format_RGB32));
+        const bool ok = m_surface->start(QVideoSurfaceFormat(rotatedSize, QVideoFrame::Format_ARGB32));
         if (!ok)
             qWarning() << "Unable to start camera viewfinder surface";
     }
@@ -1139,6 +1036,8 @@ bool BbCameraSession::startViewFinder()
 
 void BbCameraSession::stopViewFinder()
 {
+    m_windowGrabber->stop();
+
     m_status = QCamera::StoppingStatus;
     emit statusChanged(m_status);
 
@@ -1188,7 +1087,14 @@ void BbCameraSession::applyConfiguration()
 
         Q_ASSERT(viewfinderResolution.isValid());
 
+        const QByteArray windowId = QString().sprintf("qcamera_vf_%p", this).toLatin1();
+        m_windowGrabber->setWindowId(windowId);
+
+        const QByteArray windowGroupId = m_windowGrabber->windowGroupId();
+
         camera_error_t result = camera_set_photovf_property(m_handle,
+                                                            CAMERA_IMGPROP_WIN_GROUPID, windowGroupId.data(),
+                                                            CAMERA_IMGPROP_WIN_ID, windowId.data(),
                                                             CAMERA_IMGPROP_WIDTH, viewfinderResolution.width(),
                                                             CAMERA_IMGPROP_HEIGHT, viewfinderResolution.height(),
                                                             CAMERA_IMGPROP_FORMAT, CAMERA_FRAMETYPE_NV12,

src/plugins/blackberry/camera/bbcamerasession.h

@@ -57,6 +57,7 @@
 QT_BEGIN_NAMESPACE
 
 class BbCameraOrientationHandler;
+class WindowGrabber;
 
 class BbCameraSession : public QObject
 {
@@ -137,10 +138,6 @@ public:
     QAudioEncoderSettings audioSettings() const;
     void setAudioSettings(const QAudioEncoderSettings &settings);
 
-    // methods invoked from BB10 camera API callbacks in separated thread
-    void handlePhotoViewFinderData(camera_buffer_t*);
-    void handleVideoViewFinderData(camera_buffer_t*);
-
 Q_SIGNALS:
     // camera control
     void statusChanged(QCamera::Status);
@@ -178,6 +175,7 @@ private slots:
     void handleVideoRecordingResumed();
     void deviceOrientationChanged(int);
     void handleCameraPowerUp();
+    void viewfinderFrameGrabbed(const QImage &image);
 
 private:
     bool openCamera();
@@ -227,6 +225,8 @@ private:
     BbMediaStorageLocation m_mediaStorageLocation;
 
     camera_handle_t m_handle;
+
+    WindowGrabber* m_windowGrabber;
 };
 
 QDebug operator<<(QDebug debug, camera_error_t error);

src/plugins/blackberry/common/common.pri

@@ -0,0 +1,7 @@
+INCLUDEPATH += $$PWD
+
+HEADERS += \
+    $$PWD/windowgrabber.h
+
+SOURCES += \
+    $$PWD/windowgrabber.cpp

src/plugins/blackberry/common/windowgrabber.cpp

@@ -0,0 +1,291 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Research In Motion
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part 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 "windowgrabber.h"
+
+#include <QAbstractEventDispatcher>
+#include <QDebug>
+#include <QGuiApplication>
+#include <QImage>
+#include <qpa/qplatformnativeinterface.h>
+
+#include <bps/screen.h>
+#include <errno.h>
+
+QT_BEGIN_NAMESPACE
+
+WindowGrabber::WindowGrabber(QObject *parent)
+    : QObject(parent),
+      m_screenBuffer(0),
+      m_active(false),
+      m_screenContextInitialized(false),
+      m_screenPixmapInitialized(false),
+      m_screenPixmapBufferInitialized(false)
+{
+    // grab the window frame with 60 frames per second
+    m_timer.setInterval(1000/60);
+
+    connect(&m_timer, SIGNAL(timeout()), SLOT(grab()));
+
+    QCoreApplication::eventDispatcher()->installNativeEventFilter(this);
+}
+
+WindowGrabber::~WindowGrabber()
+{
+    QCoreApplication::eventDispatcher()->removeNativeEventFilter(this);
+}
+
+void WindowGrabber::setFrameRate(int frameRate)
+{
+    m_timer.setInterval(1000/frameRate);
+}
+
+void WindowGrabber::setWindowId(const QByteArray &windowId)
+{
+    m_windowId = windowId;
+}
+
+void WindowGrabber::start()
+{
+    int result = 0;
+
+    result = screen_create_context(&m_screenContext, SCREEN_APPLICATION_CONTEXT);
+    if (result != 0) {
+        qWarning() << "WindowGrabber: cannot create screen context:" << strerror(errno);
+        return;
+    } else {
+        m_screenContextInitialized = true;
+    }
+
+    result = screen_create_pixmap(&m_screenPixmap, m_screenContext);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot create pixmap:" << strerror(errno);
+        return;
+    } else {
+        m_screenPixmapInitialized = true;
+    }
+
+    const int usage = SCREEN_USAGE_READ | SCREEN_USAGE_NATIVE;
+    result = screen_set_pixmap_property_iv(m_screenPixmap, SCREEN_PROPERTY_USAGE, &usage);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot set pixmap usage:" << strerror(errno);
+        return;
+    }
+
+    const int format = SCREEN_FORMAT_RGBA8888;
+    result = screen_set_pixmap_property_iv(m_screenPixmap, SCREEN_PROPERTY_FORMAT, &format);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot set pixmap format:" << strerror(errno);
+        return;
+    }
+
+    int size[2] = { 0, 0 };
+    result = screen_get_window_property_iv(m_window, SCREEN_PROPERTY_SIZE, size);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot get window size:" << strerror(errno);
+        return;
+    }
+
+    m_screenBufferWidth = size[0];
+    m_screenBufferHeight = size[1];
+
+    result = screen_set_pixmap_property_iv(m_screenPixmap, SCREEN_PROPERTY_BUFFER_SIZE, size);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot set pixmap size:" << strerror(errno);
+        return;
+    }
+
+    result = screen_create_pixmap_buffer(m_screenPixmap);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot create pixmap buffer:" << strerror(errno);
+        return;
+    }
+
+    result = screen_get_pixmap_property_pv(m_screenPixmap, SCREEN_PROPERTY_RENDER_BUFFERS, (void**)&m_screenPixmapBuffer);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot get pixmap buffer:" << strerror(errno);
+        return;
+    } else {
+        m_screenPixmapBufferInitialized = true;
+    }
+
+    result = screen_get_buffer_property_pv(m_screenPixmapBuffer, SCREEN_PROPERTY_POINTER, (void**)&m_screenBuffer);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot get pixmap buffer pointer:" << strerror(errno);
+        return;
+    }
+
+    result = screen_get_buffer_property_iv(m_screenPixmapBuffer, SCREEN_PROPERTY_STRIDE, &m_screenBufferStride);
+    if (result != 0) {
+        cleanup();
+        qWarning() << "WindowGrabber: cannot get pixmap buffer stride:" << strerror(errno);
+        return;
+    }
+
+    m_timer.start();
+
+    m_active = true;
+}
+
+void WindowGrabber::stop()
+{
+    if (!m_active)
+        return;
+
+    cleanup();
+
+    m_timer.stop();
+
+    m_active = false;
+}
+
+void WindowGrabber::pause()
+{
+    m_timer.stop();
+}
+
+void WindowGrabber::resume()
+{
+    if (!m_active)
+        return;
+
+    m_timer.start();
+}
+
+bool WindowGrabber::nativeEventFilter(const QByteArray&, void *message, long*)
+{
+    bps_event_t * const event = static_cast<bps_event_t *>(message);
+
+    if (event && bps_event_get_domain(event) == screen_get_domain()) {
+        const screen_event_t screen_event = screen_event_get_event(event);
+
+        int eventType;
+        if (screen_get_event_property_iv(screen_event, SCREEN_PROPERTY_TYPE, &eventType) != 0) {
+            qWarning() << "WindowGrabber: Failed to query screen event type";
+            return false;
+        }
+
+        if (eventType != SCREEN_EVENT_CREATE)
+            return false;
+
+        screen_window_t window = 0;
+        if (screen_get_event_property_pv(screen_event, SCREEN_PROPERTY_WINDOW, (void**)&window) != 0) {
+            qWarning() << "WindowGrabber: Failed to query window property";
+            return false;
+        }
+
+        const int maxIdStrLength = 128;
+        char idString[maxIdStrLength];
+        if (screen_get_window_property_cv(window, SCREEN_PROPERTY_ID_STRING, maxIdStrLength, idString) != 0) {
+            qWarning() << "WindowGrabber: Failed to query window ID string";
+            return false;
+        }
+
+        if (m_windowId == idString) {
+            m_window = window;
+            start();
+        }
+    }
+
+    return false;
+}
+
+QByteArray WindowGrabber::windowGroupId() const
+{
+    QWindow *window = QGuiApplication::allWindows().isEmpty() ? 0 : QGuiApplication::allWindows().first();
+    if (!window)
+        return QByteArray();
+
+    QPlatformNativeInterface * const nativeInterface = QGuiApplication::platformNativeInterface();
+    if (!nativeInterface) {
+        qWarning() << "WindowGrabber: Unable to get platform native interface";
+        return QByteArray();
+    }
+
+    const char * const groupIdData = static_cast<const char *>(
+        nativeInterface->nativeResourceForWindow("windowGroup", window));
+    if (!groupIdData) {
+        qWarning() << "WindowGrabber: Unable to find window group for window" << window;
+        return QByteArray();
+    }
+
+    return QByteArray(groupIdData);
+}
+
+void WindowGrabber::grab()
+{
+    const int result = screen_read_window(m_window, m_screenPixmapBuffer, 0, 0, 0);
+    if (result != 0)
+        return;
+
+    const QImage frame((unsigned char*)m_screenBuffer, m_screenBufferWidth, m_screenBufferHeight,
+                       m_screenBufferStride, QImage::Format_ARGB32);
+
+    emit frameGrabbed(frame);
+}
+
+void WindowGrabber::cleanup()
+{
+    if (m_screenPixmapBufferInitialized) {
+        screen_destroy_buffer(m_screenPixmapBuffer);
+        m_screenPixmapBufferInitialized = false;
+    }
+
+    if (m_screenPixmapInitialized) {
+        screen_destroy_pixmap(m_screenPixmap);
+        m_screenPixmapInitialized = false;
+    }
+
+    if (m_screenContextInitialized) {
+        screen_destroy_context(m_screenContext);
+        m_screenContextInitialized = false;
+    }
+}
+
+QT_END_NAMESPACE

src/plugins/blackberry/common/windowgrabber.h

@@ -0,0 +1,106 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Research In Motion
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part 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 WINDOWGRABBER_H
+#define WINDOWGRABBER_H
+
+#include <QAbstractNativeEventFilter>
+#include <QObject>
+#include <QTimer>
+
+#include <screen/screen.h>
+
+QT_BEGIN_NAMESPACE
+
+class WindowGrabber : public QObject, public QAbstractNativeEventFilter
+{
+    Q_OBJECT
+
+public:
+    explicit WindowGrabber(QObject *parent = 0);
+    ~WindowGrabber();
+
+    void setFrameRate(int frameRate);
+
+    void setWindowId(const QByteArray &windowId);
+
+    void start();
+    void stop();
+
+    void pause();
+    void resume();
+
+    bool nativeEventFilter(const QByteArray &eventType, void *message, long *result) Q_DECL_OVERRIDE;
+
+    QByteArray windowGroupId() const;
+
+signals:
+    void frameGrabbed(const QImage &frame);
+
+private slots:
+    void grab();
+
+private:
+    void cleanup();
+
+    QTimer m_timer;
+
+    QByteArray m_windowId;
+
+    screen_window_t m_window;
+    screen_context_t m_screenContext;
+    screen_pixmap_t m_screenPixmap;
+    screen_buffer_t m_screenPixmapBuffer;
+
+    char* m_screenBuffer;
+
+    int m_screenBufferWidth;
+    int m_screenBufferHeight;
+    int m_screenBufferStride;
+
+    bool m_active : 1;
+    bool m_screenContextInitialized : 1;
+    bool m_screenPixmapInitialized : 1;
+    bool m_screenPixmapBufferInitialized : 1;
+};
+
+QT_END_NAMESPACE
+
+#endif