Add a QAudioBuffer class.

Prereq for probing or decoding.  The abstract API probably needs
to change.

Change-Id: Ie0bf796c1f581f34bbc0a8af2dffc387c513a330
Reviewed-by: Jonas Rabbe <jonas.rabbe@nokia.com>

src/multimedia/audio/qaudiobuffer.h

@@ -0,0 +1,158 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** 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, Nokia gives you certain additional
+** rights. These rights are described in the Nokia 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.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QAUDIOBUFFER_H
+#define QAUDIOBUFFER_H
+
+#include <QSharedDataPointer>
+
+#include <qtmultimediadefs.h>
+#include <qtmedianamespace.h>
+
+#include <qaudio.h>
+#include <qaudioformat.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Multimedia)
+
+class QAbstractAudioBuffer;
+class QAudioBufferPrivate;
+class Q_MULTIMEDIA_EXPORT QAudioBuffer
+{
+public:
+    QAudioBuffer();
+    QAudioBuffer(QAbstractAudioBuffer *provider);
+    QAudioBuffer(const QAudioBuffer &other);
+    QAudioBuffer(const QByteArray &data, const QAudioFormat &format);
+    QAudioBuffer(int numSamples, const QAudioFormat &format); // Initialized to empty
+
+    QAudioBuffer& operator=(const QAudioBuffer &other);
+
+    ~QAudioBuffer();
+
+    bool isValid() const;
+
+    QAudioFormat format() const;
+
+    int sampleCount() const;
+    int byteCount() const;
+
+    qint64 duration() const;
+    qint64 startTime() const;
+
+    // Data modification
+    // void clear();
+    // Other ideas
+    // operator *=
+    // operator += (need to be careful about different formats)
+
+    // Data access
+    const void* constData() const; // Does not detach, preferred
+    const void* data() const; // Does not detach
+    void *data(); // detaches
+
+    // Structures for easier access to stereo data
+    template <typename T> struct StereoSampleDefault { enum { Default = 0 }; };
+
+    template <typename T> struct StereoSample {
+
+        StereoSample()
+            : left(T(StereoSampleDefault<T>::Default))
+            , right(T(StereoSampleDefault<T>::Default))
+        {
+        }
+
+        StereoSample(T leftSample, T rightSample)
+            : left(leftSample)
+            , right(rightSample)
+        {
+        }
+
+        StereoSample& operator=(const StereoSample &other)
+        {
+            // Two straight assigns is probably
+            // cheaper than a conditional check on
+            // self assignment
+            left = other.left;
+            right = other.right;
+            return *this;
+        }
+
+        T left;
+        T right;
+
+        T average() const {return (left + right) / 2;}
+        void clear() {left = right = T(StereoSampleDefault<T>::Default);}
+    };
+
+    typedef StereoSample<unsigned char> S8U;
+    typedef StereoSample<signed char> S8S;
+    typedef StereoSample<unsigned short> S16U;
+    typedef StereoSample<signed short> S16S;
+    typedef StereoSample<float> S32F;
+
+    template <typename T> const T* constData() const {
+        return static_cast<const T*>(constData());
+    }
+    template <typename T> const T* data() const {
+        return static_cast<const T*>(data());
+    }
+    template <typename T> T* data() {
+        return static_cast<T*>(data());
+    }
+private:
+    QAudioBufferPrivate *d;
+};
+
+template <> struct QAudioBuffer::StereoSampleDefault<unsigned char> { enum { Default = 128 }; };
+template <> struct QAudioBuffer::StereoSampleDefault<unsigned short> { enum { Default = 32768 }; };
+
+
+QT_END_NAMESPACE
+
+Q_DECLARE_METATYPE(QAudioBuffer)
+
+QT_END_HEADER
+
+#endif // QAUDIOBUFFER_H