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| <header/> |
| <div class="refentry" id="eglQueryContext"> |
| <div class="titlepage"/> |
| <div class="refnamediv"> |
| <h2>Name</h2> |
| <p>eglQueryContext — |
| return <abbr class="acronym">EGL</abbr> rendering context information |
| </p> |
| </div> |
| <div class="refsynopsisdiv"> |
| <h2>C Specification</h2> |
| <div class="funcsynopsis"> |
| <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table"> |
| <tr> |
| <td> |
| <code class="funcdef">EGLBoolean <strong class="fsfunc">eglQueryContext</strong>(</code> |
| </td> |
| <td>EGLDisplay <var class="pdparam">display</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLContext <var class="pdparam">context</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLint <var class="pdparam">attribute</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLint * <var class="pdparam">value</var><code>)</code>;</td> |
| </tr> |
| </table> |
| <div class="funcprototype-spacer"> </div> |
| </div> |
| </div> |
| <div class="refsect1" id="parameters"> |
| <h2>Parameters</h2> |
| <div class="variablelist"> |
| <dl class="variablelist"> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>display</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Specifies the EGL display connection. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>context</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Specifies the EGL rendering context to query. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>attribute</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Specifies the EGL rendering context attribute to be returned. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>value</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Returns the requested value. |
| </p> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="refsect1" id="description"> |
| <h2>Description</h2> |
| <p> |
| <code class="function">eglQueryContext</code> returns in |
| <em class="parameter"><code>value</code></em> the value of |
| <em class="parameter"><code>attribute</code></em> for <em class="parameter"><code>context</code></em>. |
| <em class="parameter"><code>attribute</code></em> can be one of the following: |
| </p> |
| <div class="variablelist"> |
| <dl class="variablelist"> |
| <dt> |
| <span class="term"> |
| <code class="constant">EGL_CONFIG_ID</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Returns the ID of the EGL frame buffer configuration |
| with respect to which the context was created. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="constant">EGL_CONTEXT_CLIENT_TYPE</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Returns the type of client API which the context |
| supports (one of |
| <code class="constant">EGL_OPENGL_API</code>, |
| <code class="constant">EGL_OPENGL_ES_API</code>, or |
| <code class="constant">EGL_OPENVG_API</code>). |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="constant">EGL_CONTEXT_CLIENT_VERSION</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Returns the version of the client API which the |
| context supports, as specified at context creation |
| time. The resulting value is only meaningful for an |
| OpenGL ES context. |
| </p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <code class="constant">EGL_RENDER_BUFFER</code> |
| </span> |
| </dt> |
| <dd> |
| <p> |
| Returns the buffer which client API rendering |
| via the context will use. The value returned |
| depends on properties of both the context, and |
| the surface to which the context is bound: |
| </p> |
| <div class="itemizedlist"> |
| <ul style="list-style-type: disc; " class="itemizedlist"> |
| <li class="listitem"> |
| <p> |
| If the context is bound to a pixmap surface, |
| then <code class="constant">EGL_SINGLE_BUFFER</code> will |
| be returned. |
| </p> |
| </li> |
| <li class="listitem"> |
| <p> |
| If the context is bound to a pbuffer surface, |
| then <code class="constant">EGL_BACK_BUFFER</code> will |
| be returned. |
| </p> |
| </li> |
| <li class="listitem"> |
| <p> |
| If the context is bound to a window surface, |
| then either <code class="constant">EGL_BACK_BUFFER</code> |
| or <code class="constant">EGL_SINGLE_BUFFER</code> may be |
| returned. The value returned depends on both the |
| buffer requested by the setting of the |
| <code class="constant">EGL_RENDER_BUFFER</code> property |
| of the surface (which may be queried by calling |
| <code class="function">eglQuerySurface</code>), and on |
| the client API (not all client APIs support |
| single-buffer rendering to window surfaces). |
| </p> |
| </li> |
| <li class="listitem"> |
| <p> |
| If the context is not bound to a surface, such |
| as an OpenGL ES context bound to a framebuffer |
| object, then <code class="constant">EGL_NONE</code> will |
| be returned. |
| </p> |
| </li> |
| </ul> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="refsect1" id="notes"> |
| <h2>Notes</h2> |
| <p> |
| Attributes <code class="constant">EGL_CONTEXT_CLIENT_TYPE</code> and |
| <code class="constant">EGL_RENDER_BUFFER</code> are supported only if |
| the EGL version is 1.2 or greater. |
| </p> |
| <p> |
| Attribute <code class="constant">EGL_CONTEXT_CLIENT_VERSION</code> is |
| supported only if the EGL version is 1.3 or greater. |
| </p> |
| </div> |
| <div class="refsect1" id="errors"> |
| <h2>Errors</h2> |
| <p> |
| <code class="constant">EGL_FALSE</code> is returned on failure, |
| <code class="constant">EGL_TRUE</code> otherwise. |
| <em class="parameter"><code>value</code></em> is not modified when |
| <code class="constant">EGL_FALSE</code> is returned. |
| </p> |
| <p> |
| <code class="constant">EGL_BAD_DISPLAY</code> is generated if |
| <em class="parameter"><code>display</code></em> is not an EGL display connection. |
| </p> |
| <p> |
| <code class="constant">EGL_NOT_INITIALIZED</code> is generated if |
| <em class="parameter"><code>display</code></em> has not been initialized. |
| </p> |
| <p> |
| <code class="constant">EGL_BAD_CONTEXT</code> is generated if |
| <em class="parameter"><code>context</code></em> is not an EGL rendering context. |
| </p> |
| <p> |
| <code class="constant">EGL_BAD_ATTRIBUTE</code> is generated if |
| <em class="parameter"><code>attribute</code></em> is not a valid context attribute. |
| </p> |
| </div> |
| <div class="refsect1" id="seealso"> |
| <h2>See Also</h2> |
| <p> |
| <a class="citerefentry" href="eglCreateContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreateContext</span></span></a> |
| </p> |
| </div> |
| <p> |
| </p> |
| <div class="refsect3" id="copyright"> |
| <img src="KhronosLogo.jpg"/> |
| <p> |
| Copyright © 2003-2014 The Khronos Group Inc. |
| Permission is hereby granted, free of charge, to any person obtaining a |
| copy of this software and/or associated documentation files (the |
| "Materials"), to deal in the Materials without restriction, including |
| without limitation the rights to use, copy, modify, merge, publish, |
| distribute, sublicense, and/or sell copies of the Materials, and to |
| permit persons to whom the Materials are furnished to do so, subject to |
| the condition that this copyright notice and permission notice shall be included |
| in all copies or substantial portions of the Materials. |
| </p> |
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