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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglQueryString">
<info>
<copyright>
<year>2003-2018</year>
<holder>The Khronos Group Inc.</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>eglQueryString</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>eglQueryString</refname>
<refpurpose>
return a string describing properties of the EGL client or of an
<acronym>EGL</acronym> display connection
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>char const * <function>eglQueryString</function></funcdef>
<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
<paramdef>EGLint <parameter>name</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>display</parameter></term>
<listitem>
<para>
Specifies the EGL display connection.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>name</parameter></term>
<listitem>
<para>
Specifies a symbolic constant, one of
<constant>EGL_CLIENT_APIS</constant>,
<constant>EGL_VENDOR</constant>,
<constant>EGL_VERSION</constant>, or
<constant>EGL_EXTENSIONS</constant>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>eglQueryString</function> returns a pointer to a
static, zero-terminated string describing properties of the EGL
client or of an EGL display connection.
<parameter>name</parameter> may be one of the following:
</para>
<variablelist>
<varlistentry>
<term><constant>EGL_CLIENT_APIS</constant></term>
<listitem><para>
Returns a string describing which client rendering
APIs are supported. The string contains a
space-separated list of API names. The list must
include at least one of <code>OpenGL</code>,
<code>OpenGL_ES</code>, or <code>OpenVG</code>.
These strings correspond respectively to values
<constant>EGL_OPENGL_API</constant>,
<constant>EGL_OPENGL_ES_API</constant>, and
<constant>EGL_OPENVG_API</constant> of the
<citerefentry><refentrytitle>eglBindAPI</refentrytitle></citerefentry>,
<parameter>api</parameter> argument.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_VENDOR</constant></term>
<listitem><para>
Returns the name of the vendor responsible for this EGL
implementation. The format and contents of the string
are implementation-dependent.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_VERSION</constant></term>
<listitem>
<para>
Returns a version or release number. The
<constant>EGL_VERSION</constant> string is laid out
as follows:
</para>
<para>
<replaceable>major_version</replaceable>.<replaceable>minor_version</replaceable>
space
<replaceable>vendor_specific_info</replaceable>
</para>
<para>
Both the major and minor portions of the version
number are numeric. Their values must match the
<parameter>major</parameter> and
<parameter>minor</parameter> values returned by
<citerefentry><refentrytitle>eglInitialize</refentrytitle></citerefentry>.
</para>
<para>
The vendor-specific information is optional; if
present, its format and contents are
implementation-specific.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_EXTENSIONS</constant></term>
<listitem>
<para>
Returns a space separated list of supported
extensions to EGL. If there are no extensions, then
the empty string is returned.
</para>
<para>
If <parameter>display</parameter> is
<constant>EGL_NO_DISPLAY</constant>, then the
<constant>EGL_EXTENSIONS</constant> string describes
the set of supported <firstterm>client
extensions</firstterm>. If
<parameter>display</parameter> is a valid,
initialized display, then the
<constant>EGL_EXTENSIONS</constant> string describes
the set of <firstterm>display extensions</firstterm>
supported by that display. The set of supported
client extensions is disjoint from the set of
extensions supported by any given display.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="notes"><title>Notes</title>
<para>
<constant>EGL_CLIENT_APIS</constant> is supported only if
the EGL version is 1.2 or greater.
</para>
<para>
A <parameter>display</parameter> of
<constant>EGL_NO_DISPLAY</constant> is supported only if the EGL
version is 1.5 or greater.
</para>
</refsect1>
<refsect1 xml:id="errors"><title>Errors</title>
<para>
<constant>NULL</constant> is returned on failure.
</para>
<para>
<constant>EGL_BAD_DISPLAY</constant> is generated if
<parameter>display</parameter> is not an EGL display connection,
unless <parameter>display</parameter> is
<constant>EGL_NO_DISPLAY</constant> and
<parameter>name</parameter> is
<constant>EGL_EXTENSIONS</constant>.
</para>
<para>
<constant>EGL_NOT_INITIALIZED</constant> is generated if
<parameter>display</parameter> is a valid but uninitialized
EGLDisplay.
</para>
<para>
<constant>EGL_BAD_PARAMETER</constant> is generated if
<parameter>name</parameter> is not an accepted value.
</para>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>eglBindAPI</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglGetDisplay</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglInitialize</refentrytitle></citerefentry>
</para>
</refsect1>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="copyright.xml"/>
</refentry>