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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry xml:base="" id="eglCreateWindowSurface">
<refentryinfo>
<copyright>
<year>2003-2014</year>
<holder>The Khronos Group Inc.</holder>
</copyright>
</refentryinfo>
<refmeta>
<refentrytitle>eglCreateWindowSurface</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>eglCreateWindowSurface</refname>
<refpurpose>
create a new <acronym>EGL</acronym> window surface
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>EGLSurface <function>eglCreateWindowSurface</function></funcdef>
<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
<paramdef>EGLConfig <parameter>config</parameter></paramdef>
<paramdef>NativeWindowType <parameter>native_window</parameter></paramdef>
<paramdef>EGLint const * <parameter>attrib_list</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 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>config</parameter></term>
<listitem>
<para>Specifies the EGL frame buffer configuration that defines the
frame buffer resource available to the surface.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>native_window</parameter></term>
<listitem><para>Specifies the native window.</para></listitem>
</varlistentry>
<varlistentry>
<term><parameter>attrib_list</parameter></term>
<listitem><para>
Specifies window surface attributes.
May be <constant>NULL</constant> or empty
(first attribute is <constant>EGL_NONE</constant>).
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>eglCreateWindowSurface</function> creates an EGL
window surface and returns its handle. If
<function>eglCreateWindowSurface</function> fails to create
a window surface, <constant>EGL_NO_SURFACE</constant> is
returned.
</para>
<para>
Surface attributes are specified as a list of
attribute-value pairs, terminated with
<constant>EGL_NONE</constant>. Accepted attributes
are:
</para>
<variablelist>
<varlistentry>
<term><constant>EGL_RENDER_BUFFER</constant></term>
<listitem>
<para>
Specifies which buffer should be used for client API
rendering to the window. If its value is
<constant>EGL_SINGLE_BUFFER</constant>, then client
APIs should render directly into the visible window.
If its value is
<constant>EGL_BACK_BUFFER</constant>, then client
APIs should render into the back buffer. The default
value of <constant>EGL_RENDER_BUFFER</constant> is
<constant>EGL_BACK_BUFFER</constant>.
</para>
<para>
Client APIs may not be able to respect the requested
rendering buffer. To determine the actual buffer
being rendered to by a context, call
<citerefentry><refentrytitle>eglQueryContext</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_VG_ALPHA_FORMAT</constant></term>
<listitem>
<para>
Specifies how alpha values are interpreted by OpenVG
when rendering to the surface. If its value is
<constant>EGL_VG_ALPHA_FORMAT_NONPRE</constant>,
then alpha values are not premultipled. If its value
is <constant>EGL_VG_ALPHA_FORMAT_PRE</constant>,
then alpha values are premultiplied. The default
value of <constant>EGL_VG_ALPHA_FORMAT</constant> is
<constant>EGL_VG_ALPHA_FORMAT_NONPRE</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>EGL_VG_COLORSPACE</constant></term>
<listitem>
<para>
Specifies the color space used by OpenVG when
rendering to the surface. If its value is
<constant>EGL_VG_COLORSPACE_sRGB</constant>, then a
non-linear, perceptually uniform color space is
assumed, with a corresponding
<type>VGImageFormat</type> of form
<constant>VG_s*</constant>. If its value is
<constant>EGL_VG_COLORSPACE_LINEAR</constant>, then
a linear color space is assumed, with a
corresponding <type>VGImageFormat</type> of form
<constant>VG_l*</constant>. The default value of
<constant>EGL_VG_COLORSPACE</constant> is
<constant>EGL_VG_COLORSPACE_sRGB</constant>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Any EGL rendering context that was created with respect to
<parameter>config</parameter> can be used to render into the
surface. Use
<citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry>
to attach an EGL rendering context to the surface.
</para>
<para>
Use
<citerefentry><refentrytitle>eglQuerySurface</refentrytitle></citerefentry>
to retrieve the ID of <parameter>config</parameter>.
</para>
<para>
Use
<citerefentry><refentrytitle>eglDestroySurface</refentrytitle></citerefentry>
to destroy the surface.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
Attributes <constant>EGL_RENDER_BUFFER</constant>,
<constant>EGL_VG_ALPHA_FORMAT</constant>, and
<constant>EGL_VG_COLORSPACE</constant>, and the
corresponding attribute values, are supported only if the
EGL version is 1.2 or greater.
</para>
<!-- Might want to mention aliasing of EGL_VG_* -> EGL_* that occurred in EGL 1.3 -->
<para>
The <constant>EGL_VG_ALPHA_FORMAT</constant> and
<constant>EGL_VG_COLORSPACE</constant> attributes are used
only by OpenVG. EGL itself, and other client APIs such as
OpenGL and OpenGL ES , do not distinguish multiple
colorspace models. Refer to section 11.2 of the OpenVG 1.0
specification for more information. The native window
system's use and interpretation of alpha values is outside
the scope of EGL, although the preferred behavior is for the
window system to ignore the value of
<constant>EGL_VG_ALPHA_FORMAT</constant> when compositing
window surfaces.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>EGL_NO_SURFACE</constant> is returned if creation of
the context fails.
</para>
<para>
<constant>EGL_BAD_DISPLAY</constant> is generated if
<parameter>display</parameter> is not an EGL display connection.
</para>
<para>
<constant>EGL_NOT_INITIALIZED</constant> is generated if
<parameter>display</parameter> has not been initialized.
</para>
<para>
<constant>EGL_BAD_CONFIG</constant> is generated if
<parameter>config</parameter> is not an EGL frame buffer configuration.
</para>
<para>
<constant>EGL_BAD_NATIVE_WINDOW</constant> may be generated if
<parameter>native_window</parameter> is not a valid native window.
</para>
<para>
<constant>EGL_BAD_ATTRIBUTE</constant> is generated if
<parameter>attrib_list</parameter> contains an invalid window attribute
or if an attribute value is not recognized or is out of range.
</para>
<para>
<constant>EGL_BAD_ALLOC</constant> is generated if there are not
enough resources to allocate the new surface.
</para>
<para>
<constant>EGL_BAD_MATCH</constant> is generated if the attributes of
<parameter>native_window</parameter> do not correspond to
<parameter>config</parameter> or if
<parameter>config</parameter> does not support rendering to windows
(the <constant>EGL_SURFACE_TYPE</constant> attribute does not contain
<constant>EGL_WINDOW_BIT</constant>).
</para>
<para>
<constant>EGL_BAD_MATCH</constant> is generated if
<parameter>config</parameter> does not support the specified
OpenVG alpha format attribute (the value of
<constant>EGL_VG_ALPHA_FORMAT</constant> is
<constant>EGL_VG_ALPHA_FORMAT_PRE</constant> and the
<constant>EGL_VG_ALPHA_FORMAT_PRE_BIT</constant> is not set
in the <constant>EGL_SURFACE_TYPE</constant> attribute of
<parameter>config</parameter>) or colorspace attribute (the
value of <constant>EGL_VG_COLORSPACE</constant> is
<constant>EGL_VG_COLORSPACE_LINEAR</constant> and the
<constant>EGL_VG_COLORSPACE_LINEAR_IT</constant> is not set
in the <constant>EGL_SURFACE_TYPE</constant> attribute of
<parameter>config</parameter>).
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>eglDestroySurface</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglChooseConfig</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglGetConfigs</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>eglQuerySurface</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect3 id="Copyright"><title></title>
<!-- Content included from copyright.inc.xsl -->
<imageobject>
<imagedata fileref="KhronosLogo.jpg" format="jpg" />
</imageobject>
<para />
</refsect3>
</refentry>
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