<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>