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<?xml version="1.0" encoding="iso-8859-1"?>
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<html><head><title>QAbstractVideoBuffer Class Reference</title><style>h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm }
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</style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr /><td align="left" valign="top" width="32"><img align="left" border="0" height="32" src="images/rb-logo.png" width="32" /></td><td width="1">  </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a></td></table><h1 align="center">QAbstractVideoBuffer Class Reference<br /><sup><sup>[<a href="qtmultimedia.html">QtMultimedia</a> module]</sup></sup></h1><p>The QAbstractVideoBuffer class is an abstraction for video data.
<a href="#details">More...</a></p>
<h3>Types</h3><ul><li><div class="fn" />enum <b><a href="qabstractvideobuffer.html#HandleType-enum">HandleType</a></b> { NoHandle, GLTextureHandle, XvShmImageHandle, CoreImageHandle, QPixmapHandle, UserHandle }</li><li><div class="fn" />enum <b><a href="qabstractvideobuffer.html#MapMode-enum">MapMode</a></b> { NotMapped, ReadOnly, WriteOnly, ReadWrite }</li></ul><h3>Methods</h3><ul><li><div class="fn" /><b><a href="qabstractvideobuffer.html#QAbstractVideoBuffer">__init__</a></b> (<i>self</i>, HandleType <i>type</i>)</li><li><div class="fn" />QVariant <b><a href="qabstractvideobuffer.html#handle">handle</a></b> (<i>self</i>)</li><li><div class="fn" />HandleType <b><a href="qabstractvideobuffer.html#handleType">handleType</a></b> (<i>self</i>)</li><li><div class="fn" />(object, int <i>numBytes</i>, int <i>bytesPerLine</i>) <b><a href="qabstractvideobuffer.html#map">map</a></b> (<i>self</i>, MapMode <i>mode</i>)</li><li><div class="fn" />MapMode <b><a href="qabstractvideobuffer.html#mapMode">mapMode</a></b> (<i>self</i>)</li><li><div class="fn" /><b><a href="qabstractvideobuffer.html#unmap">unmap</a></b> (<i>self</i>)</li></ul><a name="details" /><hr /><h2>Detailed Description</h2><p>The QAbstractVideoBuffer class is an abstraction for video
data.</p>
<p>The <a href="qvideoframe.html">QVideoFrame</a> class makes use
of a QAbstractVideoBuffer internally to reference a buffer of video
data. Creating a subclass of QAbstractVideoBuffer will allow you to
construct video frames from preallocated or static buffers.</p>
<p>The contents of a buffer can be accessed by mapping the buffer
to memory using the <a href="qabstractvideobuffer.html#map">map</a>() function which returns a
pointer to memory containing the contents of the the video buffer.
The memory returned by <a href="qabstractvideobuffer.html#map">map</a>() is released by calling
the <a href="qabstractvideobuffer.html#unmap">unmap</a>()
function.</p>
<p>The <a href="qabstractvideobuffer.html#handle">handle</a>() of a
buffer may also be used to manipulate it's contents using type
specific APIs. The type of a buffer's handle is given by the
<a href="qabstractvideobuffer.html#handleType">handleType</a>()
function.</p>
<hr /><h2>Type Documentation</h2><h3 class="fn"><a name="HandleType-enum" />QAbstractVideoBuffer.HandleType</h3><p>Identifies the type of a video buffers handle.</p>
<table class="valuelist">
<tr class="odd" valign="top">
<th class="tblConst">Constant</th>
<th class="tblval">Value</th>
<th class="tbldscr">Description</th>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.NoHandle</tt></td>
<td class="topAlign"><tt>0</tt></td>
<td class="topAlign">The buffer has no handle, its data can only be
accessed by mapping the buffer.</td>
</tr>
<tr>
<td class="topAlign">
<tt>QAbstractVideoBuffer.GLTextureHandle</tt></td>
<td class="topAlign"><tt>1</tt></td>
<td class="topAlign">The handle of the buffer is an OpenGL texture
ID.</td>
</tr>
<tr>
<td class="topAlign">
<tt>QAbstractVideoBuffer.XvShmImageHandle</tt></td>
<td class="topAlign"><tt>2</tt></td>
<td class="topAlign">The handle contains pointer to shared memory
XVideo image.</td>
</tr>
<tr>
<td class="topAlign">
<tt>QAbstractVideoBuffer.CoreImageHandle</tt></td>
<td class="topAlign"><tt>3</tt></td>
<td class="topAlign">The handle contains pointer to Mac OS X
CIImage.</td>
</tr>
<tr>
<td class="topAlign">
<tt>QAbstractVideoBuffer.QPixmapHandle</tt></td>
<td class="topAlign"><tt>4</tt></td>
<td class="topAlign">The handle of the buffer is a <a href="qpixmap.html">QPixmap</a>.</td>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.UserHandle</tt></td>
<td class="topAlign"><tt>1000</tt></td>
<td class="topAlign">Start value for user defined handle
types.</td>
</tr>
</table>
<p><b>See also</b> <a href="qabstractvideobuffer.html#handleType">handleType</a>().</p>
<h3 class="fn"><a name="MapMode-enum" />QAbstractVideoBuffer.MapMode</h3><p>Enumerates how a video buffer's data is mapped to memory.</p>
<table class="valuelist">
<tr class="odd" valign="top">
<th class="tblConst">Constant</th>
<th class="tblval">Value</th>
<th class="tbldscr">Description</th>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.NotMapped</tt></td>
<td class="topAlign"><tt>0x00</tt></td>
<td class="topAlign">The video buffer has is not mapped to
memory.</td>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.ReadOnly</tt></td>
<td class="topAlign"><tt>0x01</tt></td>
<td class="topAlign">The mapped memory is populated with data from
the video buffer when mapped, but the content of the mapped memory
may be discarded when unmapped.</td>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.WriteOnly</tt></td>
<td class="topAlign"><tt>0x02</tt></td>
<td class="topAlign">The mapped memory is uninitialized when
mapped, and the content will be used to populate the video buffer
when unmapped.</td>
</tr>
<tr>
<td class="topAlign"><tt>QAbstractVideoBuffer.ReadWrite</tt></td>
<td class="topAlign"><tt>ReadOnly | WriteOnly</tt></td>
<td class="topAlign">The mapped memory is populated with data from
the video buffer, and the video buffer is repopulated with the
content of the mapped memory.</td>
</tr>
</table>
<p><b>See also</b> <a href="qabstractvideobuffer.html#mapMode">mapMode</a>() and <a href="qabstractvideobuffer.html#map">map</a>().</p>
<hr /><h2>Method Documentation</h2><h3 class="fn"><a name="QAbstractVideoBuffer" />QAbstractVideoBuffer.__init__ (<i>self</i>, <a href="qabstractvideobuffer.html#HandleType-enum">HandleType</a> <i>type</i>)</h3><p>Constructs an abstract video buffer of the given
<i>type</i>.</p>
<h3 class="fn"><a name="handle" />QVariant QAbstractVideoBuffer.handle (<i>self</i>)</h3><p>Returns a type specific handle to the data buffer.</p>
<p>The type of the handle is given by <a href="qabstractvideobuffer.html#handleType">handleType</a>()
function.</p>
<p><b>See also</b> <a href="qabstractvideobuffer.html#handleType">handleType</a>().</p>
<h3 class="fn"><a name="handleType" /><a href="qabstractvideobuffer.html#HandleType-enum">HandleType</a> QAbstractVideoBuffer.handleType (<i>self</i>)</h3><p>Returns the type of a video buffer's handle.</p>
<p><b>See also</b> <a href="qabstractvideobuffer.html#handle">handle</a>().</p>
<h3 class="fn"><a name="map" />(object, int <i>numBytes</i>, int <i>bytesPerLine</i>) QAbstractVideoBuffer.map (<i>self</i>, <a href="qabstractvideobuffer.html#MapMode-enum">MapMode</a> <i>mode</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Maps the contents of a video buffer to memory.</p>
<p>The map <i>mode</i> indicates whether the contents of the mapped
memory should be read from and/or written to the buffer. If the map
mode includes the <a href="qabstractvideobuffer.html#MapMode-enum">QAbstractVideoBuffer.ReadOnly</a>
flag the mapped memory will be populated with the content of the
video buffer when mapped. If the map mode includes the <a href="qabstractvideobuffer.html#MapMode-enum">QAbstractVideoBuffer.WriteOnly</a>
flag the content of the mapped memory will be persisted in the
buffer when unmapped.</p>
<p>When access to the data is no longer needed be sure to call the
<a href="qabstractvideobuffer.html#unmap">unmap</a>() function to
release the mapped memory.</p>
<p>Returns a pointer to the mapped memory region, or a null pointer
if the mapping failed. The size in bytes of the mapped memory
region is returned in <i>numBytes</i>, and the line stride in
<i>bytesPerLine</i>.</p>
<p>When access to the data is no longer needed be sure to <a href="qabstractvideobuffer.html#unmap">unmap</a>() the buffer.</p>
<p><b>Note:</b> Writing to memory that is mapped as read-only is
undefined, and may result in changes to shared data.</p>
<p><b>See also</b> <a href="qabstractvideobuffer.html#unmap">unmap</a>() and <a href="qabstractvideobuffer.html#mapMode">mapMode</a>().</p>
<h3 class="fn"><a name="mapMode" /><a href="qabstractvideobuffer.html#MapMode-enum">MapMode</a> QAbstractVideoBuffer.mapMode (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Returns the mode a video buffer is mapped in.</p>
<p><b>See also</b> <a href="qabstractvideobuffer.html#map">map</a>().</p>
<h3 class="fn"><a name="unmap" />QAbstractVideoBuffer.unmap (<i>self</i>)</h3><p>This method is abstract and should be reimplemented in any sub-class.</p><p>Releases the memory mapped by the <a href="qabstractvideobuffer.html#map">map</a>() function</p>
<p>If the <a href="qabstractvideobuffer.html#MapMode-enum">MapMode</a> included the
<a href="qabstractvideobuffer.html#MapMode-enum">QAbstractVideoBuffer.WriteOnly</a>
flag this will persist the current content of the mapped memory to
the video frame.</p>
<p><b>See also</b> <a href="qabstractvideobuffer.html#map">map</a>().</p>
<address><hr /><div align="center"><table border="0" cellspacing="0" width="100%"><tr class="address"><td align="left" width="25%">PyQt 4.12.1 for X11</td><td align="center" width="50%">Copyright © <a href="http://www.riverbankcomputing.com">Riverbank Computing Ltd</a> and <a href="http://www.qt.io">The Qt Company</a> 2015</td><td align="right" width="25%">Qt 4.8.7</td></tr></table></div></address></body></html>
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