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#ifndef WAVEFORM_H

#define WAVEFORM_H

#include <QWidget>

#include <QtMultimedia/QAudioFormat>

#include <QPixmap>

#include <QScopedPointer>

QT_FORWARD_DECLARE_CLASS(QByteArray)

/**

 * Widget which displays a section of the audio waveform.

 *

 * The waveform is rendered on a set of QPixmaps which form a group of tiles

 * whose extent covers the widget.  As the audio position is updated, these

 * tiles are scrolled from left to right; when the left-most tile scrolls

 * outside the widget, it is moved to the right end of the tile array and

 * painted with the next section of the waveform.

 */

class Waveform : public QWidget {

    Q_OBJECT

public:

    Waveform(const QByteArray &buffer, QWidget *parent = 0);

    ~Waveform();

    // QWidget

    void paintEvent(QPaintEvent *event);

    void resizeEvent(QResizeEvent *event);

    void initialize(const QAudioFormat &format, qint64 audioBufferSize, qint64 windowDurationUs);

    void reset();

    void setAutoUpdatePosition(bool enabled);

public slots:

    void dataLengthChanged(qint64 length);

    void positionChanged(qint64 position);

private:

    static const int NullIndex = -1;

    void deletePixmaps();

    /*

     * (Re)create all pixmaps, repaint and update the display.

     * Triggers an update();

     */

    void createPixmaps(const QSize &newSize);

    /*

     * Update window position.

     * Triggers an update().

     */

    void setWindowPosition(qint64 position);

    /*

     * Base position of tile

     */

    qint64 tilePosition(int index) const;

    /*

     * Structure which identifies a point within a given

     * tile.

     */

    struct TilePoint

    {

        TilePoint(int idx = 0, qint64 pos = 0, qint64 pix = 0)

        :   index(idx), positionOffset(pos), pixelOffset(pix)

        { }

        // Index of tile

        int     index;

        // Number of bytes from start of tile

        qint64  positionOffset;

        // Number of pixels from left of corresponding pixmap

        int     pixelOffset;

    };

    /*

     * Convert position in m_buffer into a tile index and an offset in pixels

     * into the corresponding pixmap.

     *

     * \param position  Offset into m_buffer, in bytes

     * If position is outside the tile array, index is NullIndex and

     * offset is zero.

     */

    TilePoint tilePoint(qint64 position) const;

    /*

     * Convert offset in bytes into a tile into an offset in pixels

     * within that tile.

     */

    int tilePixelOffset(qint64 positionOffset) const;

    /*

     * Convert offset in bytes into the window into an offset in pixels

     * within the widget rect().

     */

    int windowPixelOffset(qint64 positionOffset) const;

    /*

     * Paint all tiles which can be painted.

     * \return true iff update() was called

     */

    bool paintTiles();

    /*

     * Paint the specified tile

     *

     * \pre Sufficient data is available to completely paint the tile, i.e.

     *      m_dataLength is greater than the upper bound of the tile.

     */

    void paintTile(int index);

    /*

     * Move the first n tiles to the end of the array, and mark them as not

     * painted.

     */

    void shuffleTiles(int n);

    /*

     * Reset tile array

     */

    void resetTiles(qint64 newStartPos);

private:

    const QByteArray&       m_buffer;

    qint64                  m_dataLength;

    qint64                  m_position;

    QAudioFormat            m_format;

    bool                    m_active;

    QSize                   m_pixmapSize;

    QVector<QPixmap*>       m_pixmaps;

    struct Tile {

        // Pointer into parent m_pixmaps array

        QPixmap*            pixmap;

        // Flag indicating whether this tile has been painted

        bool                painted;

    };

    QVector<Tile>           m_tiles;

    // Length of audio data in bytes depicted by each tile

    qint64                  m_tileLength;

    // Position in bytes of the first tile, relative to m_buffer

    qint64                  m_tileArrayStart;

    qint64                  m_windowPosition;

    qint64                  m_windowLength;

};

#endif // WAVEFORM_H