src/multimedia/video/qabstractvideobuffer.cpp
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
       
     4 ** All rights reserved.
       
     5 ** Contact: Nokia Corporation (qt-info@nokia.com)
       
     6 **
       
     7 ** This file is part of the QtMultimedia module of the Qt Toolkit.
       
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     9 ** $QT_BEGIN_LICENSE:LGPL$
       
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    16 ** GNU Lesser General Public License Usage
       
    17 ** Alternatively, this file may be used under the terms of the GNU Lesser
       
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    29 ** Nokia at qt-info@nokia.com.
       
    30 **
       
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    32 **
       
    33 **
       
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    35 **
       
    36 **
       
    37 **
       
    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 #include "qabstractvideobuffer_p.h"
       
    43 
       
    44 #include <qvariant.h>
       
    45 
       
    46 QT_BEGIN_NAMESPACE
       
    47 
       
    48 /*!
       
    49     \class QAbstractVideoBuffer
       
    50     \brief The QAbstractVideoBuffer class is an abstraction for video data.
       
    51     \preliminary
       
    52     \since 4.6
       
    53 
       
    54     The QVideoFrame class makes use of a QAbstractVideoBuffer internally to reference a buffer of
       
    55     video data.  Creating a subclass of QAbstractVideoBuffer will allow you to construct video
       
    56     frames from preallocated or static buffers.
       
    57 
       
    58     The contents of a buffer can be accessed by mapping the buffer to memory using the map()
       
    59     function which returns a pointer to memory containing the contents of the the video buffer.
       
    60     The memory returned by map() is released by calling the unmap() function.
       
    61 
       
    62     The handle() of a buffer may also be used to manipulate it's contents using type specific APIs.
       
    63     The type of a buffer's handle is given by the handleType() function.
       
    64 
       
    65     \sa QVideoFrame
       
    66 */
       
    67 
       
    68 /*!
       
    69     \enum QAbstractVideoBuffer::HandleType
       
    70 
       
    71     Identifies the type of a video buffers handle.
       
    72 
       
    73     \value NoHandle The buffer has no handle, its data can only be accessed by mapping the buffer.
       
    74     \value GLTextureHandle The handle of the buffer is an OpenGL texture ID.
       
    75     \value UserHandle Start value for user defined handle types.
       
    76 
       
    77     \sa handleType()
       
    78 */
       
    79 
       
    80 /*!
       
    81     \enum QAbstractVideoBuffer::MapMode
       
    82 
       
    83     Enumerates how a video buffer's data is mapped to memory.
       
    84 
       
    85     \value NotMapped The video buffer has is not mapped to memory.
       
    86     \value ReadOnly The mapped memory is populated with data from the video buffer when mapped, but
       
    87     the content of the mapped memory may be discarded when unmapped.
       
    88     \value WriteOnly The mapped memory in unitialized when mapped, and the content will be used to
       
    89     populate the video buffer when unmapped.
       
    90     \value ReadWrite The mapped memory is populated with data from the video buffer, and the
       
    91     video buffer is repopulated with the content of the mapped memory.
       
    92 
       
    93     \sa mapMode(), map()
       
    94 */
       
    95 
       
    96 /*!
       
    97     Constructs an abstract video buffer of the given \a type.
       
    98 */
       
    99 
       
   100 QAbstractVideoBuffer::QAbstractVideoBuffer(HandleType type)
       
   101     : d_ptr(new QAbstractVideoBufferPrivate)
       
   102 {
       
   103     Q_D(QAbstractVideoBuffer);
       
   104 
       
   105     d->handleType = type;
       
   106 }
       
   107 
       
   108 /*!
       
   109     \internal
       
   110 */
       
   111 
       
   112 QAbstractVideoBuffer::QAbstractVideoBuffer(QAbstractVideoBufferPrivate &dd, HandleType type)
       
   113     : d_ptr(&dd)
       
   114 {
       
   115     Q_D(QAbstractVideoBuffer);
       
   116 
       
   117     d->handleType = type;
       
   118 }
       
   119 
       
   120 /*!
       
   121     Destroys an abstract video buffer.
       
   122 */
       
   123 
       
   124 QAbstractVideoBuffer::~QAbstractVideoBuffer()
       
   125 {
       
   126     delete d_ptr;
       
   127 }
       
   128 
       
   129 /*!
       
   130     Returns the type of a video buffer's handle.
       
   131 
       
   132     \sa handle()
       
   133 */
       
   134 
       
   135 QAbstractVideoBuffer::HandleType QAbstractVideoBuffer::handleType() const
       
   136 {
       
   137     return d_func()->handleType;
       
   138 }
       
   139 
       
   140 /*!
       
   141     \fn QAbstractVideoBuffer::mapMode() const
       
   142 
       
   143     Returns the mode a video buffer is mapped in.
       
   144 
       
   145     \sa map()
       
   146 */
       
   147 
       
   148 /*!
       
   149     \fn QAbstractVideoBuffer::map(MapMode mode, int *numBytes, int *bytesPerLine)
       
   150 
       
   151     Maps the contents of a video buffer to memory.
       
   152 
       
   153     The map \a mode indicates whether the contents of the mapped memory should be read from and/or
       
   154     written to the buffer.  If the map mode includes the QAbstractVideoBuffer::ReadOnly flag the
       
   155     mapped memory will be populated with the content of the video buffer when mapped.  If the map
       
   156     mode includes the QAbstractVideoBuffer::WriteOnly flag the content of the mapped memory will be
       
   157     persisted in the buffer when unmapped.
       
   158 
       
   159     When access to the data is no longer needed be sure to call the unmap() function to release the
       
   160     mapped memory.
       
   161 
       
   162     Returns a pointer to the mapped memory region, or a null pointer if the mapping failed.  The
       
   163     size in bytes of the mapped memory region is returned in \a numBytes, and the line stride in \a
       
   164     bytesPerLine.
       
   165 
       
   166     When access to the data is no longer needed be sure to unmap() the buffer.
       
   167 
       
   168     \note Writing to memory that is mapped as read-only is undefined, and may result in changes
       
   169     to shared data.
       
   170 
       
   171     \sa unmap(), mapMode()
       
   172 */
       
   173 
       
   174 /*!
       
   175     \fn QAbstractVideoBuffer::unmap()
       
   176 
       
   177     Releases the memory mapped by the map() function
       
   178 
       
   179     If the \l {QAbstractVideoBuffer::MapMode}{MapMode} included the QAbstractVideoBuffer::WriteOnly
       
   180     flag this will persist the current content of the mapped memory to the video frame.
       
   181 
       
   182     \sa map()
       
   183 */
       
   184 
       
   185 /*!
       
   186     Returns a type specific handle to the data buffer.
       
   187 
       
   188     The type of the handle is given by handleType() function.
       
   189 
       
   190     \sa handleType()
       
   191 */
       
   192 
       
   193 QVariant QAbstractVideoBuffer::handle() const
       
   194 {
       
   195     return QVariant();
       
   196 }
       
   197 
       
   198 
       
   199 QT_END_NAMESPACE