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https://github.com/openharmony/third_party_egl.git
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lizheng
99 lines
4.4 KiB
XML
Executable File
99 lines
4.4 KiB
XML
Executable File
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglGetProcAddress">
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<info>
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<copyright>
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<year>2003-2018</year>
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<holder>The Khronos Group Inc.</holder>
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</copyright>
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</info>
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<refmeta>
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<refentrytitle>eglGetProcAddress</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>eglGetProcAddress</refname>
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<refpurpose>
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return a <acronym>GL</acronym> or an <acronym>EGL</acronym>
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extension function
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</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void (* <function>eglGetProcAddress</function></funcdef>
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<paramdef>char const * <parameter>procname</parameter>))(void</paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 xml:id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>procname</parameter></term>
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<listitem>
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<para>
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Specifies the name of the function to return.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 xml:id="description"><title>Description</title>
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<para>
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<function>eglGetProcAddress</function> returns the address of
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the client API or EGL function named by
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<parameter>procname</parameter>. <parameter>procname</parameter>
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must be a null-terminated string. The pointer returned should be
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cast to a function pointer matching the function's definition in
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the corresponding API or extension specification. A return value
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of <constant>NULL</constant> indicates that the specific
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function does not exist for the implementation.
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</para>
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<para>
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A non-<constant>NULL</constant> return value does not guarantee
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that an extension function is actually supported at runtime. The
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client must also make a corresponding query, such as
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<function>glGetString</function>(<constant>GL_EXTENSIONS</constant>)
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for OpenGL and OpenGL ES extensions;
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<function>vgGetString</function>(<constant>VG_EXTENSIONS</constant>)
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for OpenVG extensions;
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<function>eglQueryString</function>(<parameter>display</parameter>,
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<constant>EGL_EXTENSIONS</constant>); or query the EGL or client
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API version for non-extension functions, to determine if a
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function is supported by EGL or a specific client API context.
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</para>
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<para>
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Client API function pointers returned by
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<function>eglGetProcAddress</function> are independent of the
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display and the currently bound client API context, and may be
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used by any client API context which supports the function.
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</para>
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<para>
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<function>eglGetProcAddress</function> may be queried for all
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EGL and client API functions supported by the implementation
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(whether those functions are extensions or not, and whether they
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are supported by the current client API context or not).
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</para>
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<para>
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For functions that are queryable with
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<function>eglGetProcAddress</function>, implementations may
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choose to also export those functions statically from the object
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libraries implementing those functions. However, portable
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clients cannot rely on this behavior.
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</para>
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</refsect1>
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<refsect1 xml:id="notes"><title>Notes</title>
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<para>
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If the EGL version is not 1.5 or greater, only queries of EGL
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and client API <emphasis>extension</emphasis> functions will
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succeed.
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</para>
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</refsect1>
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<refsect1 xml:id="seealso"><title>See Also</title>
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<para>
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<function>glGetString</function>
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<citerefentry><refentrytitle>eglQueryString</refentrytitle></citerefentry> </para>
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<function>vgGetString</function>
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</refsect1>
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<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="copyright.xml"/>
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</refentry>
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