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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title xmlns:xlink="http://www.w3.org/1999/xlink">eglQuerySurface - EGL Reference Pages</title>
<link rel="stylesheet" type="text/css" href="khronos-man.css"/>
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"/>
</head>
<body>
<header/>
<div class="refentry" id="eglQuerySurface">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>eglQuerySurface —
return <abbr class="acronym">EGL</abbr> surface 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">eglQuerySurface</strong>(</code>
</td>
<td>EGLDisplay <var class="pdparam">display</var>, </td>
</tr>
<tr>
<td> </td>
<td>EGLSurface <var class="pdparam">surface</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>surface</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies the EGL surface to query.
</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>attribute</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies the EGL surface 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">eglQuerySurface</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>surface</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 surface was created.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_GL_COLORSPACE</code>
</span>
</dt>
<dd>
<p>
Returns the color space used by OpenGL and OpenGL ES
when rendering to the surface, either
<code class="constant">EGL_GL_COLORSPACE_SRGB</code> or
<code class="constant">EGL_GL_COLORSPACE_LINEAR</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_HEIGHT</code>
</span>
</dt>
<dd>
<p>
Returns the height of the surface in pixels.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_HORIZONTAL_RESOLUTION</code>
</span>
</dt>
<dd>
<p>
Returns the horizontal dot pitch of the display on
which a window surface is visible. The value
returned is equal to the actual dot pitch, in
pixels/meter, multiplied by the constant value
<code class="constant">EGL_DISPLAY_SCALING</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_LARGEST_PBUFFER</code>
</span>
</dt>
<dd>
<p>
Returns the same attribute value specified when the
surface was created with
<a class="citerefentry" href="eglCreatePbufferSurface.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreatePbufferSurface</span></span></a>.
For a window or pixmap surface,
<em class="parameter"><code>value</code></em> is not modified.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_MIPMAP_LEVEL</code>
</span>
</dt>
<dd>
<p>
Returns which level of the mipmap to render to, if
texture has mipmaps.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_MIPMAP_TEXTURE</code>
</span>
</dt>
<dd>
<p>
Returns <code class="constant">EGL_TRUE</code> if texture has
mipmaps, <code class="constant">EGL_FALSE</code> otherwise.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_MULTISAMPLE_RESOLVE</code>
</span>
</dt>
<dd>
<p>
Returns the filter used when resolving the
multisample buffer. The filter may be either
<code class="constant">EGL_MULTISAMPLE_RESOLVE_DEFAULT</code>
or <code class="constant">EGL_MULTISAMPLE_RESOLVE_BOX</code>,
as described for
<a class="citerefentry" href="eglSurfaceAttrib.xhtml"><span class="citerefentry"><span class="refentrytitle">eglSurfaceAttrib</span></span></a>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_PIXEL_ASPECT_RATIO</code>
</span>
</dt>
<dd>
<p>
Returns the aspect ratio of an individual pixel (the
ratio of a pixel's width to its height). The value
returned is equal to the actual aspect ratio
multiplied by the constant value
<code class="constant">EGL_DISPLAY_SCALING</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_RENDER_BUFFER</code>
</span>
</dt>
<dd>
<p>
Returns the buffer which client API rendering is
requested to use. For a window surface, this is the
same attribute value specified when the surface was
created. For a pbuffer surface, it is always
<code class="constant">EGL_BACK_BUFFER</code>. For a pixmap
surface, it is always
<code class="constant">EGL_SINGLE_BUFFER</code>. To determine
the actual buffer being rendered to by a context,
call
<a class="citerefentry" href="eglQueryContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglQueryContext</span></span></a>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_SWAP_BEHAVIOR</code>
</span>
</dt>
<dd>
<p>
Returns the effect on the color buffer when posting
a surface with
<a class="citerefentry" href="eglSwapBuffers.xhtml"><span class="citerefentry"><span class="refentrytitle">eglSwapBuffers</span></span></a>.
Swap behavior may be either
<code class="constant">EGL_BUFFER_PRESERVED</code> or
<code class="constant">EGL_BUFFER_DESTROYED</code>, as
described for
<a class="citerefentry" href="eglSurfaceAttrib.xhtml"><span class="citerefentry"><span class="refentrytitle">eglSurfaceAttrib</span></span></a>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_TEXTURE_FORMAT</code>
</span>
</dt>
<dd>
<p>
Returns format of texture. Possible values are
<code class="constant">EGL_NO_TEXTURE</code>,
<code class="constant">EGL_TEXTURE_RGB</code>, and
<code class="constant">EGL_TEXTURE_RGBA</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_TEXTURE_TARGET</code>
</span>
</dt>
<dd>
<p>
Returns type of texture. Possible values are
<code class="constant">EGL_NO_TEXTURE</code>, or
<code class="constant">EGL_TEXTURE_2D</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_VERTICAL_RESOLUTION</code>
</span>
</dt>
<dd>
<p>
Returns the vertical dot pitch of the display on
which a window surface is visible. The value
returned is equal to the actual dot pitch, in
pixels/meter, multiplied by the constant value
<code class="constant">EGL_DISPLAY_SCALING</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_VG_ALPHA_FORMAT</code>
</span>
</dt>
<dd>
<p>
Returns the interpretation of alpha values used by
OpenVG when rendering to the surface, either
<code class="constant">EGL_VG_ALPHA_FORMAT_NONPRE</code> or
<code class="constant">EGL_VG_ALPHA_FORMAT_PRE</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_VG_COLORSPACE</code>
</span>
</dt>
<dd>
<p>
Returns the color space used by OpenVG when rendering to
the surface, either
<code class="constant">EGL_VG_COLORSPACE_sRGB</code> or
<code class="constant">EGL_VG_COLORSPACE_LINEAR</code>.
</p>
</dd>
<dt>
<span class="term">
<code class="constant">EGL_WIDTH</code>
</span>
</dt>
<dd>
<p>
Returns the width of the surface in pixels.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="notes">
<h2>Notes</h2>
<p>
Attribute <code class="constant">EGL_GL_COLORSPACE</code> is supported
only if the EGL version is 1.5 or greater.
</p>
<p>
Attribute <code class="constant">EGL_MULTISAMPLE_RESOLVE</code> is
supported only if the EGL version is 1.4 or greater.
</p>
<p>
Attributes <code class="constant">EGL_DISPLAY_SCALING</code>.
<code class="constant">EGL_HORIZONTAL_RESOLUTION</code>,
<code class="constant">EGL_PIXEL_ASPECT_RATIO</code>,
<code class="constant">EGL_RENDER_BUFFER</code>,
<code class="constant">EGL_SWAP_BEHAVIOR</code>, and
<code class="constant">EGL_VERTICAL_RESOLUTION</code> are supported
only if the EGL version is 1.2 or greater.
</p>
<p>
Querying attributes <code class="constant">EGL_TEXTURE_FORMAT</code>,
<code class="constant">EGL_TEXTURE_TARGET</code>,
<code class="constant">EGL_MIPMAP_TEXTURE</code>, or
<code class="constant">EGL_MIPMAP_LEVEL</code> for a non-pbuffer
surface is not an error, but <em class="parameter"><code>value</code></em> is
not modified.
</p>
<p>
<code class="constant">EGL_DISPLAY_SCALING</code> is the constant
value 10000. Floating-point values such as resolution and
pixel aspect ratio are scaled by this value before being
returned as integers so that sufficient precision to be
meaningful will be retained in the returned value.
</p>
<p>
For an offscreen (pbuffer or pixmap) surface, or a surface
whose pixel dot pitch or aspect ratio are unknown, querying
<code class="constant">EGL_HORIZONTAL_RESOLUTION</code>,
<code class="constant">EGL_PIXEL_ASPECT_RATIO</code>, or
<code class="constant">EGL_VERTICAL_RESOLUTION</code> will return the
constant value <code class="constant">EGL_UNKNOWN</code> (-1).
</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_SURFACE</code> is generated if
<em class="parameter"><code>surface</code></em> is not an EGL surface.
</p>
<p>
<code class="constant">EGL_BAD_ATTRIBUTE</code> is generated if
<em class="parameter"><code>attribute</code></em> is not a valid surface attribute.
</p>
</div>
<div class="refsect1" id="seealso">
<h2>See Also</h2>
<p>
<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="eglSurfaceAttrib.xhtml"><span class="citerefentry"><span class="refentrytitle">eglSurfaceAttrib</span></span></a>,
<a class="citerefentry" href="eglSwapBuffers.xhtml"><span class="citerefentry"><span class="refentrytitle">eglSwapBuffers</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>
</div>
<p>
</p>
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