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| <header/> |
| <div class="refentry" id="eglMakeCurrent"> |
| <div class="titlepage"/> |
| <div class="refnamediv"> |
| <h2>Name</h2> |
| <p>eglMakeCurrent — |
| attach an EGL rendering context to EGL surfaces |
| </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">eglMakeCurrent</strong>(</code> |
| </td> |
| <td>EGLDisplay <var class="pdparam">display</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLSurface <var class="pdparam">draw</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLSurface <var class="pdparam">read</var>, </td> |
| </tr> |
| <tr> |
| <td> </td> |
| <td>EGLContext <var class="pdparam">context</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 <abbr class="acronym">EGL</abbr> display connection.</p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>draw</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p>Specifies the <abbr class="acronym">EGL</abbr> draw surface.</p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>read</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p>Specifies the <abbr class="acronym">EGL</abbr> read surface.</p> |
| </dd> |
| <dt> |
| <span class="term"> |
| <em class="parameter"> |
| <code>context</code> |
| </em> |
| </span> |
| </dt> |
| <dd> |
| <p>Specifies the <abbr class="acronym">EGL</abbr> rendering context |
| to be attached to the surfaces. |
| </p> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="refsect1" id="description"> |
| <h2>Description</h2> |
| <p> |
| <code class="function">eglMakeCurrent</code> binds <em class="parameter"><code>context</code></em> |
| to the current rendering thread and to the <em class="parameter"><code>draw</code></em> |
| and <em class="parameter"><code>read</code></em> surfaces. |
| </p> |
| <p> |
| For an OpenGL or OpenGL ES context, <em class="parameter"><code>draw</code></em> |
| is used for all operations except for any pixel data read back or copied |
| (<a class="citerefentry" href="glReadPixels.xhtml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>, |
| <a class="citerefentry" href="glCopyTexImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>, and |
| <a class="citerefentry" href="glCopyTexSubImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>), |
| which is taken from the frame buffer values of |
| <em class="parameter"><code>read</code></em>. Note that the same |
| <span class="type">EGLSurface</span> may be specified for both draw and read. |
| </p> |
| <p> |
| For an OpenVG context, the same <span class="type">EGLSurface</span> must be |
| specified for both <em class="parameter"><code>draw</code></em> and |
| <em class="parameter"><code>read</code></em>. |
| </p> |
| <p> |
| If the calling thread has already a current rendering context of |
| the same client API type as <em class="parameter"><code>context</code></em>, then |
| that context is flushed and marked as no longer current. |
| <em class="parameter"><code>context</code></em> is then made the current context |
| for the calling thread. For purposes of |
| <code class="function">eglMakeCurrent</code>, the client API type of all |
| OpenGL ES and OpenGL contexts is considered the same. In other |
| words, if any OpenGL ES context is currently bound and |
| <em class="parameter"><code>context</code></em> is an OpenGL context, or if any |
| OpenGL context is currently bound and |
| <em class="parameter"><code>context</code></em> is an OpenGL ES context, the |
| currently bound context will be made no longer current and |
| <em class="parameter"><code>context</code></em> will be made current. |
| </p> |
| <p> |
| OpenGL and OpenGL ES buffer mappings created by e.g. |
| <code class="function">glMapBuffer</code> are not affected by |
| <code class="function">eglMakeCurrent</code>; they persist whether the |
| context owning the buffer is current or not. |
| </p> |
| <p> |
| If <em class="parameter"><code>draw</code></em> is destroyed after |
| <code class="function">eglMakeCurrent</code> is called, then subsequent |
| rendering commands will be processed and the context state will |
| be updated, but the surface contents become undefined. If |
| <em class="parameter"><code>read</code></em> is destroyed after |
| <code class="function">eglMakeCurrent</code> then pixel values |
| <em class="parameter"><code>read</code></em> from the framebuffer (e.g., as |
| result of calling glReadPixels) are undefined. If a native |
| window or pixmap underlying the <em class="parameter"><code>draw</code></em> or |
| <em class="parameter"><code>read</code></em> surfaces is destroyed, rendering and |
| <em class="parameter"><code>read</code></em>back are handled as above. |
| </p> |
| <p> |
| To release the current context without assigning a new one, set |
| <em class="parameter"><code>context</code></em> to |
| <code class="constant">EGL_NO_CONTEXT</code> and set |
| <em class="parameter"><code>draw</code></em> and <em class="parameter"><code>read</code></em> to |
| <code class="constant">EGL_NO_SURFACE</code> . The currently bound |
| context for the client API specified by the current rendering |
| API is flushed and marked as no longer current, and there will |
| be no current context for that client API after |
| <code class="function">eglMakeCurrent</code> returns. This is the only |
| case in which <code class="function">eglMakeCurrent</code> respects the |
| current rendering API. In all other cases, the client API |
| affected is determined by <em class="parameter"><code>context</code></em>. This |
| is the only case where an uninitialized display may be passed to |
| <code class="function">eglMakeCurrent</code>. |
| </p> |
| <p> |
| If ctx is not <code class="constant">EGL_NO_CONTEXT</code>, then both |
| <em class="parameter"><code>draw</code></em> and <em class="parameter"><code>read</code></em> must |
| not be <code class="constant">EGL_NO_SURFACE</code> unless |
| <em class="parameter"><code>context</code></em> is a context which supports being |
| bound without read and draw surfaces. In this case the context |
| is made current without a default framebuffer. The meaning of |
| this is defined by the client API of the supporting context (see |
| chapter 4 of the OpenGL 3.0 Specification, and the |
| <code class="constant">GL_OES_surfaceless_context</code> OpenGL ES |
| extension.). |
| </p> |
| <p> |
| The first time a OpenGL or OpenGL ES context is made current the |
| viewport and scissor dimensions are set to the size of the |
| <em class="parameter"><code>draw</code></em> surface (as though |
| <code class="function">glViewport</code>(0,0,w,h) and |
| <code class="function">glScissor</code>(0,0,<em class="parameter"><code>w</code></em>,<em class="parameter"><code>h</code></em>) |
| were called, where <em class="parameter"><code>w</code></em> and |
| <em class="parameter"><code>h</code></em> are the width and height of the |
| surface, respectively). However, the viewport and scissor |
| dimensions are not modified when <em class="parameter"><code>context</code></em> |
| is subsequently made current. The client is responsible for |
| resetting the viewport and scissor in this case. |
| </p> |
| <p> |
| The first time <em class="parameter"><code>context</code></em> is made current, |
| if it is without a default framebuffer (e.g. both |
| <em class="parameter"><code>draw</code></em> and <em class="parameter"><code>read</code></em> are |
| <code class="constant">EGL_NO_SURFACE</code> ), then the viewport and |
| scissor regions are set as though |
| <code class="function">glViewport</code>(0,0,0,0) and |
| <code class="function">glScissor</code>(0,0,0,0) were called. |
| </p> |
| <p> |
| Implementations may delay allocation of auxiliary buffers for a |
| surface until they are required by a context (which may result |
| in the <code class="constant">EGL_BAD_ALLOC</code> error described |
| above). Once allocated, however, auxiliary buffers and their |
| contents persist until a surface is deleted. |
| </p> |
| <p> |
| Use |
| <a class="citerefentry" href="eglGetCurrentContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentContext</span></span></a>, |
| <a class="citerefentry" href="eglGetCurrentDisplay.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentDisplay</span></span></a>, and |
| <a class="citerefentry" href="eglGetCurrentSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentSurface</span></span></a> |
| to query the current rendering context and associated display connection and surfaces. |
| </p> |
| </div> |
| <div class="refsect1" id="errors"> |
| <h2>Errors</h2> |
| <p> |
| If <em class="parameter"><code>draw</code></em> or <em class="parameter"><code>read</code></em> |
| are not compatible with <em class="parameter"><code>context</code></em>, then an |
| <code class="constant">EGL_BAD_MATCH</code> error is generated. |
| </p> |
| <p> |
| If <em class="parameter"><code>context</code></em> is current to some other |
| thread, or if either <em class="parameter"><code>draw</code></em> or |
| <em class="parameter"><code>read</code></em> are bound to contexts in another |
| thread, an <code class="constant">EGL_BAD_ACCESS</code> error is |
| generated. |
| </p> |
| <p> |
| If binding <em class="parameter"><code>context</code></em> would exceed the |
| number of current contexts of that client API type supported by |
| the implementation, an <code class="constant">EGL_BAD_ACCESS</code> error |
| is generated. |
| </p> |
| <p> |
| If either <em class="parameter"><code>draw</code></em> or |
| <em class="parameter"><code>read</code></em> are pbuffers created with |
| <code class="function">eglCreatePbufferFromClientBuffer</code>, and the |
| underlying bound client API buffers are in use by the client API |
| that created them, an <code class="constant">EGL_BAD_ACCESS</code> error |
| is generated. |
| </p> |
| <p> |
| If <em class="parameter"><code>context</code></em> is not a valid context and is |
| not <code class="constant">EGL_NO_CONTEXT</code>, an |
| <code class="constant">EGL_BAD_CONTEXT</code> error is generated. |
| </p> |
| <p> |
| If either <em class="parameter"><code>draw</code></em> or |
| <em class="parameter"><code>read</code></em> are not valid EGL surfaces and are |
| not <code class="constant">EGL_NO_SURFACE</code>, an |
| <code class="constant">EGL_BAD_SURFACE</code> error is generated. |
| </p> |
| <p> |
| If <em class="parameter"><code>context</code></em> is |
| <code class="constant">EGL_NO_CONTEXT</code> and either |
| <em class="parameter"><code>draw</code></em> or <em class="parameter"><code>read</code></em> are |
| not <code class="constant">EGL_NO_SURFACE</code>, an |
| <code class="constant">EGL_BAD_MATCH</code> error is generated. |
| </p> |
| <p> |
| If either of <em class="parameter"><code>draw</code></em> or |
| <em class="parameter"><code>read</code></em> is a valid surface and the other is |
| <code class="constant">EGL_NO_SURFACE</code>, an |
| <code class="constant">EGL_BAD_MATCH</code> error is generated. |
| </p> |
| <p> |
| If <em class="parameter"><code>context</code></em> does not support being bound |
| without <em class="parameter"><code>read</code></em> and |
| <em class="parameter"><code>draw</code></em> surfaces, and both |
| <em class="parameter"><code>draw</code></em> and <em class="parameter"><code>read</code></em> are |
| <code class="constant">EGL_NO_SURFACE</code>, an |
| <code class="constant">EGL_BAD_MATCH</code> error is generated. |
| </p> |
| <p> |
| If a native window underlying either <em class="parameter"><code>draw</code></em> |
| or <em class="parameter"><code>read</code></em> is no longer valid, an |
| <code class="constant">EGL_BAD_NATIVE_WINDOW</code> error is generated. |
| </p> |
| <p> |
| If <em class="parameter"><code>draw</code></em> and <em class="parameter"><code>read</code></em> |
| cannot fit into graphics memory simultaneously, an |
| <code class="constant">EGL_BAD_MATCH</code> error is generated. |
| </p> |
| <p> |
| If the previous context of the calling thread has unflushed |
| commands, and the previous surface is no longer valid, an |
| <code class="constant">EGL_BAD_CURRENT_SURFACE</code> error is generated. |
| </p> |
| <p> |
| If the ancillary buffers for <em class="parameter"><code>draw</code></em> and |
| <em class="parameter"><code>read</code></em> cannot be allocated, an |
| <code class="constant">EGL_BAD_ALLOC</code> error is generated. |
| </p> |
| <p> |
| If a power management event has occurred, an |
| <code class="constant">EGL_CONTEXT_LOST</code> error is generated. |
| </p> |
| <p> |
| If any of the following are true: |
| |
| </p> |
| <div class="itemizedlist"> |
| <ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem"> |
| <p> |
| <em class="parameter"><code>context</code></em> is not |
| <code class="constant">EGL_NO_CONTEXT</code> |
| </p> |
| </li> |
| <li class="listitem"> |
| <p> |
| <em class="parameter"><code>read</code></em> is not |
| <code class="constant">EGL_NO_SURFACE</code> |
| </p> |
| </li> |
| <li class="listitem"> |
| <p> |
| <em class="parameter"><code>draw</code></em> is not |
| <code class="constant">EGL_NO_SURFACE</code> |
| </p> |
| </li> |
| </ul> |
| </div> |
| <p> |
| |
| then an <code class="constant">EGL_NOT_INITIALIZED</code> error is |
| generated if <em class="parameter"><code>display</code></em> is a valid but |
| uninitialized display. |
| </p> |
| <p> |
| As with other commands taking <span class="type">EGLDisplay</span> |
| parameters, if <em class="parameter"><code>display</code></em> is not a valid |
| <span class="type">EGLDisplay</span> handle, an |
| <code class="constant">EGL_BAD_DISPLAY</code> error is generated. (Some |
| implementations have chosen to allow |
| <code class="constant">EGL_NO_DISPLAY</code> as a valid |
| <em class="parameter"><code>display</code></em> parameter for |
| <code class="function">eglMakeCurrent</code>. This behavior is not |
| portable to all EGL implementations, and should be considered as |
| an undocumented vendor extension). |
| </p> |
| </div> |
| <div class="refsect1" id="seealso"> |
| <h2>See Also</h2> |
| <p> |
| <a class="citerefentry" href="glReadPixels.xhtml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>, |
| <a class="citerefentry" href="glCopyTexImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>, |
| <a class="citerefentry" href="glCopyTexSubImage2D.xhtml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>, |
| <a class="citerefentry" href="eglCreateContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreateContext</span></span></a>, |
| <a class="citerefentry" href="eglCreatePbufferSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreatePbufferSurface</span></span></a>, |
| <a class="citerefentry" href="eglCreatePixmapSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreatePixmapSurface</span></span></a>, |
| <a class="citerefentry" href="eglCreateWindowSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreateWindowSurface</span></span></a>, |
| <a class="citerefentry" href="eglGetCurrentContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentContext</span></span></a>, |
| <a class="citerefentry" href="eglGetCurrentDisplay.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentDisplay</span></span></a>, |
| <a class="citerefentry" href="eglGetCurrentSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentSurface</span></span></a>, |
| <a class="citerefentry" href="eglGetDisplay.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetDisplay</span></span></a>, |
| <a class="citerefentry" href="eglInitialize.xhtml"><span class="citerefentry"><span class="refentrytitle">eglInitialize</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. |
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