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/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.
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+** 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