1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" 3 "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> 4<refentry xml:base="" id="eglReleaseThread"> 5 <refentryinfo> 6 <copyright> 7 <year>2003-2014</year> 8 <holder>The Khronos Group Inc.</holder> 9 </copyright> 10 </refentryinfo> 11 <refmeta> 12 <refentrytitle>eglReleaseThread</refentrytitle> 13 <manvolnum>3G</manvolnum> 14 </refmeta> 15 <refnamediv> 16 <refname>eglReleaseThread</refname> 17 <refpurpose>Release EGL per-thread state</refpurpose> 18 </refnamediv> 19 <refsynopsisdiv><title>C Specification</title> 20 <funcsynopsis> 21 <funcprototype> 22 <funcdef>EGLBoolean <function>eglReleaseThread</function></funcdef> 23 <void/> 24 </funcprototype> 25 </funcsynopsis> 26 </refsynopsisdiv> 27 <refsect1 id="description"><title>Description</title> 28 <para> 29 <function>eglReleaseThread</function> returns the EGL to its 30 state at thread initialization, releasing all per-thread 31 state including the error status returned by 32 <command>eglGetError</command>, the currently bound 33 rendering API defined by <command>eglBindAPI</command>, and 34 the current contexts for each supported client API. The 35 overhead of maintaining this state may be objectionable in 36 applications which create and destroy many threads, but only 37 call EGL or client APIs in a few of those threads at any 38 given time. 39 </para> 40 <para> 41 <constant>EGL_TRUE</constant> is returned on success, and the 42 following actions are taken: 43 </para> 44 <itemizedlist> 45 <listitem> 46 <para> 47 For each client API supported by EGL, if there is a 48 currently bound context, that context is released. 49 This is equivalent to calling 50 <function>eglMakeCurrent</function> with ctx set to 51 <constant>EGL_NO_CONTEXT</constant> and both draw 52 and read set to <constant>EGL_NO_SURFACE</constant> 53 (see section 3.7.3). 54 </para> 55 </listitem> 56 <listitem> 57 <para> 58 The current rendering API is reset to its value at 59 thread initialization (see 60 <command>eglBindAPI</command>). 61 </para> 62 </listitem> 63 <listitem> 64 <para> 65 Any additional implementation-dependent per-thread 66 state maintained by EGL is marked for deletion as 67 soon as possible. 68 </para> 69 </listitem> 70 </itemizedlist> 71 <para> 72 <function>eglReleaseThread</function> may be called in any 73 thread at any time, and may be called more than once in a 74 single thread. The initialization status of EGL (see section 75 3.2) is not affected by releasing the thread; only 76 per-thread state is affected. 77 </para> 78 <para> 79 Resources explicitly allocated by calls to EGL, such as 80 contexts, surfaces, and configuration lists, are not 81 affected by <function>eglReleaseThread</function>. Such 82 resources belong not to the thread, but to the EGL 83 implementation as a whole. 84 </para> 85 </refsect1> 86 <refsect1 id="notes"><title>Notes</title> 87 <para> 88 <function>eglReleaseThread</function> is supported only if the 89 EGL version is 1.2 or greater. 90 </para> 91 <para> 92 Applications may call other EGL routines from a thread 93 following <function>eglReleaseThread</function>, but any 94 such call may reallocate the EGL state previously released. 95 In particular, calling <function>eglGetError</function> 96 immediately following a successful call to 97 <function>eglReleaseThread</function> will return 98 <constant>EGL_SUCCESS</constant>, but will also result in 99 reallocating per-thread state. 100 </para> 101 </refsect1> 102 <refsect1 id="errors"><title>Errors</title> 103 <para> 104 <constant>EGL_FALSE</constant> is returned on failure, 105 <constant>EGL_TRUE</constant> otherwise. There are no 106 defined conditions under which failure will occur. Even if 107 EGL is not initialized on any EGLDisplay, 108 <function>eglReleaseThread</function> should succeed. 109 </para> 110 <para> 111 However, platform-dependent failures may be signaled through 112 the value returned from <function>eglGetError</function>. 113 Unless the platform-dependent behavior is known, a failed 114 call to <function>eglReleaseThread</function> should be 115 assumed to leave the current rendering API, and the 116 currently bound contexts for each supported client API, in 117 an unknown state. 118 </para> 119 </refsect1> 120 <refsect1 id="seealso"><title>See Also</title> 121 <para> 122 <citerefentry><refentrytitle>eglBindAPI</refentrytitle></citerefentry>, 123 <citerefentry><refentrytitle>eglGetError</refentrytitle></citerefentry>, 124 <citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry> 125 </para> 126 </refsect1> 127 <refsect3 id="Copyright"><title></title> 128 <!-- Content included from copyright.inc.xsl --> 129 <imageobject> 130 <imagedata fileref="KhronosLogo.jpg" format="jpg" /> 131 </imageobject> 132 <para /> 133 </refsect3> 134</refentry> 135
