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<?xml version="1.0" encoding="UTF-8"?>
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<!-- qabstractvideosurface.cpp -->
  <title>Qt 4.8: QAbstractVideoSurface Class Reference</title>
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    <a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
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<div class="toc">
<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#public-types">Public Types</a></li>
<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#signals">Signals</a></li>
<li class="level1"><a href="#protected-functions">Protected Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QAbstractVideoSurface Class Reference</h1>
<!-- $$$QAbstractVideoSurface-brief -->
<p>The QAbstractVideoSurface class is a base class for video presentation surfaces. <a href="#details">More...</a></p>
<!-- @@@QAbstractVideoSurface -->
<pre class="cpp"> <span class="preprocessor">#include &lt;QAbstractVideoSurface&gt;</span></pre><p><b>Inherits: </b><a href="qobject.html">QObject</a>.</p>
<p>This class was introduced in Qt 4.6.</p>
<ul>
<li><a href="qabstractvideosurface-members.html">List of all members, including inherited members</a></li>
</ul>
<a name="public-types"></a>
<h2>Public Types</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> enum </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#Error-enum">Error</a></b> { NoError, UnsupportedFormatError, IncorrectFormatError, StoppedError, ResourceError }</td></tr>
</table>
<a name="public-functions"></a>
<h2>Public Functions</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#QAbstractVideoSurface">QAbstractVideoSurface</a></b> ( QObject * <i>parent</i> = 0 )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#dtor.QAbstractVideoSurface">~QAbstractVideoSurface</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> Error </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#error">error</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#isActive">isActive</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#isFormatSupported">isFormatSupported</a></b> ( const QVideoSurfaceFormat &amp; <i>format</i> ) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QVideoSurfaceFormat </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#nearestFormat">nearestFormat</a></b> ( const QVideoSurfaceFormat &amp; <i>format</i> ) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#present">present</a></b> ( const QVideoFrame &amp; <i>frame</i> ) = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual bool </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#start">start</a></b> ( const QVideoSurfaceFormat &amp; <i>format</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#stop">stop</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QList&lt;QVideoFrame::PixelFormat&gt; </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#supportedPixelFormats">supportedPixelFormats</a></b> ( QAbstractVideoBuffer::HandleType <i>type</i> = QAbstractVideoBuffer::NoHandle ) const = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> QVideoSurfaceFormat </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#surfaceFormat">surfaceFormat</a></b> () const</td></tr>
</table>
<ul>
<li class="fn">29 public functions inherited from <a href="qobject.html#public-functions">QObject</a></li>
</ul>
<a name="signals"></a>
<h2>Signals</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#activeChanged">activeChanged</a></b> ( bool <i>active</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#supportedFormatsChanged">supportedFormatsChanged</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#surfaceFormatChanged">surfaceFormatChanged</a></b> ( const QVideoSurfaceFormat &amp; <i>format</i> )</td></tr>
</table>
<ul>
<li class="fn">1 signal inherited from <a href="qobject.html#signals">QObject</a></li>
</ul>
<a name="protected-functions"></a>
<h2>Protected Functions</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qabstractvideosurface.html#setError">setError</a></b> ( Error <i>error</i> )</td></tr>
</table>
<ul>
<li class="fn">8 protected functions inherited from <a href="qobject.html#protected-functions">QObject</a></li>
</ul>
<h3>Additional Inherited Members</h3>
<ul>
<li class="fn">1 property inherited from <a href="qobject.html#properties">QObject</a></li>
<li class="fn">1 public slot inherited from <a href="qobject.html#public-slots">QObject</a></li>
<li class="fn">7 static public members inherited from <a href="qobject.html#static-public-members">QObject</a></li>
</ul>
<a name="details"></a>
<!-- $$$QAbstractVideoSurface-description -->
<div class="descr">
<h2>Detailed Description</h2>
<p>The QAbstractVideoSurface class is a base class for video presentation surfaces.</p>
<p>The QAbstractVideoSurface class defines the standard interface that video producers use to inter-operate with video presentation surfaces. It is not supposed to be instantiated directly. Instead, you should subclass it to create new video surfaces.</p>
<p>A video surface presents a continuous stream of identically formatted frames, where the format of each frame is compatible with a stream format supplied when starting a presentation.</p>
<p>A list of pixel formats a surface can present is given by the <a href="qabstractvideosurface.html#supportedPixelFormats">supportedPixelFormats</a>() function, and the <a href="qabstractvideosurface.html#isFormatSupported">isFormatSupported</a>() function will test if a video surface format is supported. If a format is not supported the <a href="qabstractvideosurface.html#nearestFormat">nearestFormat</a>() function may be able to suggest a similar format. For example if a surface supports fixed set of resolutions it may suggest the smallest supported resolution that contains the proposed resolution.</p>
<p>The <a href="qabstractvideosurface.html#start">start</a>() function takes a supported format and enables a video surface. Once started a surface will begin displaying the frames it receives in the <a href="qabstractvideosurface.html#present">present</a>() function. Surfaces may hold a reference to the buffer of a presented video frame until a new frame is presented or streaming is stopped. The <a href="qabstractvideosurface.html#stop">stop</a>() function will disable a surface and a release any video buffers it holds references to.</p>
</div>
<!-- @@@QAbstractVideoSurface -->
<div class="types">
<h2>Member Type Documentation</h2>
<!-- $$$Error$$$NoError$$$UnsupportedFormatError$$$IncorrectFormatError$$$StoppedError$$$ResourceError -->
<h3 class="fn"><a name="Error-enum"></a>enum QAbstractVideoSurface::<span class="name">Error</span></h3>
<p>This enum describes the errors that may be returned by the <a href="qabstractvideosurface.html#error">error</a>() function.</p>
<table class="valuelist"><tr valign="top" class="odd"><th class="tblConst">Constant</th><th class="tblval">Value</th><th class="tbldscr">Description</th></tr>
<tr><td class="topAlign"><tt>QAbstractVideoSurface::NoError</tt></td><td class="topAlign"><tt>0</tt></td><td class="topAlign">No error occurred.</td></tr>
<tr><td class="topAlign"><tt>QAbstractVideoSurface::UnsupportedFormatError</tt></td><td class="topAlign"><tt>1</tt></td><td class="topAlign">A video format was not supported.</td></tr>
<tr><td class="topAlign"><tt>QAbstractVideoSurface::IncorrectFormatError</tt></td><td class="topAlign"><tt>2</tt></td><td class="topAlign">A video frame was not compatible with the format of the surface.</td></tr>
<tr><td class="topAlign"><tt>QAbstractVideoSurface::StoppedError</tt></td><td class="topAlign"><tt>3</tt></td><td class="topAlign">The surface has not been started.</td></tr>
<tr><td class="topAlign"><tt>QAbstractVideoSurface::ResourceError</tt></td><td class="topAlign"><tt>4</tt></td><td class="topAlign">The surface could not allocate some resource.</td></tr>
</table>
<!-- @@@Error -->
</div>
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$QAbstractVideoSurface[overload1]$$$QAbstractVideoSurfaceQObject* -->
<h3 class="fn"><a name="QAbstractVideoSurface"></a>QAbstractVideoSurface::<span class="name">QAbstractVideoSurface</span> ( <span class="type"><a href="qobject.html">QObject</a></span> * <i>parent</i> = 0 )</h3>
<p>Constructs a video surface with the given <i>parent</i>.</p>
<!-- @@@QAbstractVideoSurface -->
<!-- $$$~QAbstractVideoSurface[overload1]$$$~QAbstractVideoSurface -->
<h3 class="fn"><a name="dtor.QAbstractVideoSurface"></a>QAbstractVideoSurface::<span class="name">~QAbstractVideoSurface</span> ()</h3>
<p>Destroys a video surface.</p>
<!-- @@@~QAbstractVideoSurface -->
<!-- $$$activeChanged[overload1]$$$activeChangedbool -->
<h3 class="fn"><a name="activeChanged"></a><span class="type">void</span> QAbstractVideoSurface::<span class="name">activeChanged</span> ( <span class="type">bool</span> <i>active</i> )<tt> [signal]</tt></h3>
<p>Signals that the <i>active</i> state of a video surface has changed.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#isActive">isActive</a>(), <a href="qabstractvideosurface.html#start">start</a>(), and <a href="qabstractvideosurface.html#stop">stop</a>().</p>
<!-- @@@activeChanged -->
<!-- $$$error[overload1]$$$error -->
<h3 class="fn"><a name="error"></a><span class="type"><a href="qabstractvideosurface.html#Error-enum">Error</a></span> QAbstractVideoSurface::<span class="name">error</span> () const</h3>
<p>Returns the last error that occurred.</p>
<p>If a surface fails to <a href="qabstractvideosurface.html#start">start</a>(), or stops unexpectedly this function can be called to discover what error occurred.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#setError">setError</a>().</p>
<!-- @@@error -->
<!-- $$$isActive[overload1]$$$isActive -->
<h3 class="fn"><a name="isActive"></a><span class="type">bool</span> QAbstractVideoSurface::<span class="name">isActive</span> () const</h3>
<p>Indicates whether a video surface has been started.</p>
<p>Returns true if the surface has been started, and false otherwise.</p>
<!-- @@@isActive -->
<!-- $$$isFormatSupported[overload1]$$$isFormatSupportedconstQVideoSurfaceFormat& -->
<h3 class="fn"><a name="isFormatSupported"></a><span class="type">bool</span> QAbstractVideoSurface::<span class="name">isFormatSupported</span> ( const <span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> &amp; <i>format</i> ) const<tt> [virtual]</tt></h3>
<p>Tests a video surface <i>format</i> to determine if a surface can accept it.</p>
<p>Returns true if the format is supported by the surface, and false otherwise.</p>
<!-- @@@isFormatSupported -->
<!-- $$$nearestFormat[overload1]$$$nearestFormatconstQVideoSurfaceFormat& -->
<h3 class="fn"><a name="nearestFormat"></a><span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> QAbstractVideoSurface::<span class="name">nearestFormat</span> ( const <span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> &amp; <i>format</i> ) const<tt> [virtual]</tt></h3>
<p>Returns a supported video surface format that is similar to <i>format</i>.</p>
<p>A similar surface format is one that has the same <a href="qvideosurfaceformat.html#pixelFormat">pixel format</a> and <a href="qvideosurfaceformat.html#handleType">handle type</a> but differs in some of the other properties. For example if there are restrictions on the <a href="qvideosurfaceformat.html#frameSize">frame sizes</a> a video surface can accept it may suggest a format with a larger frame size and a <a href="qvideosurfaceformat.html#viewport">viewport</a> the size of the original frame size.</p>
<p>If the format is already supported it will be returned unchanged, or if there is no similar supported format an invalid format will be returned.</p>
<!-- @@@nearestFormat -->
<!-- $$$present[overload1]$$$presentconstQVideoFrame& -->
<h3 class="fn"><a name="present"></a><span class="type">bool</span> QAbstractVideoSurface::<span class="name">present</span> ( const <span class="type"><a href="qvideoframe.html">QVideoFrame</a></span> &amp; <i>frame</i> )<tt> [pure virtual]</tt></h3>
<p>Presents a video <i>frame</i>.</p>
<p>Returns true if the frame was presented, and false if an error occurred.</p>
<p>Not all surfaces will block until the presentation of a frame has completed. Calling present() on a non-blocking surface may fail if called before the presentation of a previous frame has completed. In such cases the surface may not return to a ready state until it's had an opportunity to process events.</p>
<p>If present() fails for any other reason the surface will immediately enter the stopped state and an <a href="qabstractvideosurface.html#error">error</a>() value will be set.</p>
<p>A video surface must be in the started state for present() to succeed, and the format of the video frame must be compatible with the current video surface format.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#error">error</a>().</p>
<!-- @@@present -->
<!-- $$$setError[overload1]$$$setErrorError -->
<h3 class="fn"><a name="setError"></a><span class="type">void</span> QAbstractVideoSurface::<span class="name">setError</span> ( <span class="type"><a href="qabstractvideosurface.html#Error-enum">Error</a></span> <i>error</i> )<tt> [protected]</tt></h3>
<p>Sets the value of <a href="qabstractvideosurface.html#error">error</a>() to <i>error</i>.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#error">error</a>().</p>
<!-- @@@setError -->
<!-- $$$start[overload1]$$$startconstQVideoSurfaceFormat& -->
<h3 class="fn"><a name="start"></a><span class="type">bool</span> QAbstractVideoSurface::<span class="name">start</span> ( const <span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> &amp; <i>format</i> )<tt> [virtual]</tt></h3>
<p>Starts a video surface presenting <i>format</i> frames.</p>
<p>Returns true if the surface was started, and false if an error occurred.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#isActive">isActive</a>() and <a href="qabstractvideosurface.html#stop">stop</a>().</p>
<!-- @@@start -->
<!-- $$$stop[overload1]$$$stop -->
<h3 class="fn"><a name="stop"></a><span class="type">void</span> QAbstractVideoSurface::<span class="name">stop</span> ()<tt> [virtual]</tt></h3>
<p>Stops a video surface presenting frames and releases any resources acquired in <a href="qabstractvideosurface.html#start">start</a>().</p>
<p><b>See also </b><a href="qabstractvideosurface.html#isActive">isActive</a>() and <a href="qabstractvideosurface.html#start">start</a>().</p>
<!-- @@@stop -->
<!-- $$$supportedFormatsChanged[overload1]$$$supportedFormatsChanged -->
<h3 class="fn"><a name="supportedFormatsChanged"></a><span class="type">void</span> QAbstractVideoSurface::<span class="name">supportedFormatsChanged</span> ()<tt> [signal]</tt></h3>
<p>Signals that the set of formats supported by a video surface has changed.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#supportedPixelFormats">supportedPixelFormats</a>() and <a href="qabstractvideosurface.html#isFormatSupported">isFormatSupported</a>().</p>
<!-- @@@supportedFormatsChanged -->
<!-- $$$supportedPixelFormats[overload1]$$$supportedPixelFormatsQAbstractVideoBuffer::HandleType -->
<h3 class="fn"><a name="supportedPixelFormats"></a><span class="type"><a href="qlist.html">QList</a></span>&lt;<span class="type"><a href="qvideoframe.html#PixelFormat-enum">QVideoFrame::PixelFormat</a></span>&gt; QAbstractVideoSurface::<span class="name">supportedPixelFormats</span> ( <span class="type"><a href="qabstractvideobuffer.html#HandleType-enum">QAbstractVideoBuffer::HandleType</a></span> <i>type</i> = QAbstractVideoBuffer::NoHandle ) const<tt> [pure virtual]</tt></h3>
<p>Returns a list of pixel formats a video surface can present for a given handle <i>type</i>.</p>
<p>The pixel formats returned for the <a href="qabstractvideobuffer.html#HandleType-enum">QAbstractVideoBuffer::NoHandle</a> type are valid for any buffer that can be mapped in read-only mode.</p>
<p>Types that are first in the list can be assumed to be faster to render.</p>
<!-- @@@supportedPixelFormats -->
<!-- $$$surfaceFormat[overload1]$$$surfaceFormat -->
<h3 class="fn"><a name="surfaceFormat"></a><span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> QAbstractVideoSurface::<span class="name">surfaceFormat</span> () const</h3>
<p>Returns the format of a video surface.</p>
<!-- @@@surfaceFormat -->
<!-- $$$surfaceFormatChanged[overload1]$$$surfaceFormatChangedconstQVideoSurfaceFormat& -->
<h3 class="fn"><a name="surfaceFormatChanged"></a><span class="type">void</span> QAbstractVideoSurface::<span class="name">surfaceFormatChanged</span> ( const <span class="type"><a href="qvideosurfaceformat.html">QVideoSurfaceFormat</a></span> &amp; <i>format</i> )<tt> [signal]</tt></h3>
<p>Signals that the configured <i>format</i> of a video surface has changed.</p>
<p><b>See also </b><a href="qabstractvideosurface.html#surfaceFormat">surfaceFormat</a>() and <a href="qabstractvideosurface.html#start">start</a>().</p>
<!-- @@@surfaceFormatChanged -->
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