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<td >Qt 5.9</td><td ><a href="qtplatformheaders-index.html">Qt Platform Headers</a></td><td ><a href="qtplatformheaders-module.html">C++ Classes</a></td><td >QWGLNativeContext</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QWGLNativeContext Class</h1>
<!-- $$$QWGLNativeContext-brief -->
<p>A class encapsulating a WGL context on Windows with desktop OpenGL (opengl32.dll) <a href="#details">More...</a></p>
<!-- @@@QWGLNativeContext -->
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<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QWGLNativeContext></span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Since:</td><td class="memItemRight bottomAlign"> Qt 5.4</td></tr></table></div><ul>
<li><a href="qwglnativecontext-members.html">List of all members, including inherited members</a></li>
</ul>
<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qwglnativecontext.html#QWGLNativeContext">QWGLNativeContext</a></b>()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qwglnativecontext.html#QWGLNativeContext-1">QWGLNativeContext</a></b>(HGLRC <i>ctx</i>, HWND <i>wnd</i>)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> HGLRC </td><td class="memItemRight bottomAlign"><b><a href="qwglnativecontext.html#context">context</a></b>() const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> HWND </td><td class="memItemRight bottomAlign"><b><a href="qwglnativecontext.html#window">window</a></b>() const</td></tr>
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<!-- $$$QWGLNativeContext-description -->
<div class="descr">
<h2 id="details">Detailed Description</h2>
<p>A class encapsulating a WGL context on Windows with desktop OpenGL (opengl32.dll)</p>
<p><b>Note: </b>There is no binary compatibility guarantee for this class, meaning that an application using it is only guaranteed to work with the Qt version it was developed against.</p><p><a href="qwglnativecontext.html">QWGLNativeContext</a> is a value class that can be passed to <a href="../qtgui/qopenglcontext.html#setNativeHandle">QOpenGLContext::setNativeHandle</a>(). When creating a <a href="../qtgui/qopenglcontext.html">QOpenGLContext</a> with the native handle set, no new context will get created. Instead, the provided handles are used, without taking ownership. This allows wrapping a context created by an external framework or rendering engine. The typical usage will be similar to the following snippet:</p>
<pre class="cpp">
<span class="preprocessor">#include <QtPlatformSupport/QWGLNativeContext></span>
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>create and retrieve the WGL context and the corresponding window<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
<span class="type"><a href="../qtgui/qopenglcontext.html">QOpenGLContext</a></span> <span class="operator">*</span>context <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="../qtgui/qopenglcontext.html">QOpenGLContext</a></span>;
<span class="type"><a href="qwglnativecontext.html#QWGLNativeContext">QWGLNativeContext</a></span> nativeContext(hglrc<span class="operator">,</span> hwnd);
context<span class="operator">-</span><span class="operator">></span>setNativeHandle(<span class="type"><a href="../qtcore/qvariant.html">QVariant</a></span><span class="operator">::</span>fromValue(nativeContext));
context<span class="operator">-</span><span class="operator">></span>create();
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
</pre>
<p>The window is needed because the its pixel format will be queried. When the adoption is successful, <a href="../qtgui/qopenglcontext.html#format">QOpenGLContext::format</a>() will return a <a href="../qtgui/qsurfaceformat.html">QSurfaceFormat</a> describing this pixel format.</p>
<p>It is recommended to restrict the usage of QOpenGLContexts created this way. Various platform-specific behavior and issues may prevent such contexts to be made current with windows (surfaces) created by Qt due to non-matching pixel formats for example. A potentially safer solution is to use the wrapped context only to set up sharing and perform Qt-based rendering offscreen, using a separate, dedicated <a href="../qtgui/qopenglcontext.html">QOpenGLContext</a>. The resulting textures are then accessible in the foreign context too.</p>
<pre class="cpp">
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>like above<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
<span class="type"><a href="../qtgui/qopenglcontext.html">QOpenGLContext</a></span> <span class="operator">*</span>qtcontext <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="../qtgui/qopenglcontext.html">QOpenGLContext</a></span>;
qtcontext<span class="operator">-</span><span class="operator">></span>setShareContext(context);
qtcontext<span class="operator">-</span><span class="operator">></span>setFormat(context<span class="operator">-</span><span class="operator">></span>format());
qtcontext<span class="operator">-</span><span class="operator">></span>create();
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>use qtcontext <span class="keyword">for</span> rendering with <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
</pre>
<p>In addition to being used with <a href="../qtgui/qopenglcontext.html#setNativeHandle">QOpenGLContext::setNativeHandle</a>(), this class is used also to retrieve the native context handle, that is, a HGLRC value, from a <a href="../qtgui/qopenglcontext.html">QOpenGLContext</a>. Calling <a href="../qtgui/qopenglcontext.html#nativeHandle">QOpenGLContext::nativeHandle</a>() returns a <a href="../qtcore/qvariant.html">QVariant</a> which, on Windows with opengl32.dll at least, will contain a <a href="qwglnativecontext.html">QWGLNativeContext</a>:</p>
<pre class="cpp">
<span class="type"><a href="../qtcore/qvariant.html">QVariant</a></span> nativeHandle <span class="operator">=</span> context<span class="operator">-</span><span class="operator">></span>nativeHandle();
<span class="keyword">if</span> (<span class="operator">!</span>nativeHandle<span class="operator">.</span>isNull() <span class="operator">&</span><span class="operator">&</span> nativeHandle<span class="operator">.</span>canConvert<span class="operator"><</span><span class="type"><a href="qwglnativecontext.html#QWGLNativeContext">QWGLNativeContext</a></span><span class="operator">></span>()) {
<span class="type"><a href="qwglnativecontext.html#QWGLNativeContext">QWGLNativeContext</a></span> nativeContext <span class="operator">=</span> nativeHandle<span class="operator">.</span>value<span class="operator"><</span><span class="type"><a href="qwglnativecontext.html#QWGLNativeContext">QWGLNativeContext</a></span><span class="operator">></span>();
HGLRC hglrc <span class="operator">=</span> nativeContext<span class="operator">.</span>context();
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
}
</pre>
</div>
<p><b>See also </b><a href="../qtgui/qopenglcontext.html#setNativeHandle">QOpenGLContext::setNativeHandle</a>() and <a href="../qtgui/qopenglcontext.html#nativeHandle">QOpenGLContext::nativeHandle</a>().</p>
<!-- @@@QWGLNativeContext -->
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$QWGLNativeContext[overload1]$$$QWGLNativeContext -->
<h3 class="fn" id="QWGLNativeContext"><a name="QWGLNativeContext"></a>QWGLNativeContext::<span class="name">QWGLNativeContext</span>()</h3>
<p>Construct a new instance with no handles.</p>
<!-- @@@QWGLNativeContext -->
<!-- $$$QWGLNativeContext$$$QWGLNativeContextHGLRCHWND -->
<h3 class="fn" id="QWGLNativeContext-1"><a name="QWGLNativeContext-1"></a>QWGLNativeContext::<span class="name">QWGLNativeContext</span>(<span class="type">HGLRC</span> <i>ctx</i>, <span class="type">HWND</span> <i>wnd</i>)</h3>
<p>Constructs a new instance with the provided <i>ctx</i> context handle and <i>wnd</i> window handle.</p>
<p><b>Note: </b>The window specified by <i>wnd</i> must have its pixel format set to a format compatible with the context's. If no SetPixelFormat() call was made on any device context belonging to the window, adopting the context will fail.</p><!-- @@@QWGLNativeContext -->
<!-- $$$context[overload1]$$$context -->
<h3 class="fn" id="context"><a name="context"></a><span class="type">HGLRC</span> QWGLNativeContext::<span class="name">context</span>() const</h3>
<p>Returns the WGL context.</p>
<!-- @@@context -->
<!-- $$$window[overload1]$$$window -->
<h3 class="fn" id="window"><a name="window"></a><span class="type">HWND</span> QWGLNativeContext::<span class="name">window</span>() const</h3>
<p><b>Note: </b>The window handle is not available when the <a href="qwglnativecontext.html">QWGLNativeContext</a> is queried from a regular, non-adopted <a href="../qtgui/qopenglcontext.html">QOpenGLContext</a> using <a href="../qtgui/qopenglcontext.html#nativeHandle">QOpenGLContext::nativeHandle</a>(). This is because the <i>windows</i> platform plugin creates WGL contexts using a dummy window that is not available afterwards. Instead, the native window handle (HWND) is queriable from a <a href="../qtgui/qwindow.html">QWindow</a> via <a href="../qtgui/qplatformnativeinterface.html#nativeResourceForWindow">QPlatformNativeInterface::nativeResourceForWindow</a>() using the <i>"handle"</i> resource key. Note however that the window will not have its pixel format set until it is first associated with a context via <a href="../qtgui/qopenglcontext.html#makeCurrent">QOpenGLContext::makeCurrent</a>().</p><p>Returns handle for the window for which the context was created.</p>
<!-- @@@window -->
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