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https://github.com/openharmony/third_party_egl.git
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lizheng
271 lines
13 KiB
XML
271 lines
13 KiB
XML
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:base="" xml:id="eglCreatePlatformPixmapSurface">
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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>eglCreatePlatformPixmapSurface</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>eglCreatePlatformPixmapSurface</refname>
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<refpurpose>
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create a new <acronym>EGL</acronym> offscreen surface
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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>EGLSurface <function>eglCreatePlatformPixmapSurface</function></funcdef>
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<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
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<paramdef>EGLConfig <parameter>config</parameter></paramdef>
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<paramdef>void * <parameter>native_pixmap</parameter></paramdef>
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<paramdef>EGLint const * <parameter>attrib_list</parameter></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>display</parameter></term>
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<listitem><para>Specifies the EGL display connection.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>config</parameter></term>
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<listitem><para>
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Specifies the EGL frame buffer configuration that defines the
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frame buffer resource available to the surface.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>native_pixmap</parameter></term>
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<listitem><para>Specifies the native pixmap.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>attrib_list</parameter></term>
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<listitem><para>
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Specifies pixmap surface attributes.
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May be <constant>NULL</constant> or empty
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(first attribute is <constant>EGL_NONE</constant>).
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</para></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>eglCreatePlatformPixmapSurface</function> creates an
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off-screen <acronym>EGL</acronym> pixmap surface and returns
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a handle to it.
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</para>
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<para>
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If <function>eglCreatePlatformPixmapSurface</function> fails to
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create a pixmap surface, <constant>EGL_NO_SURFACE</constant> is
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returned.
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</para>
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<para>
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<parameter>native_pixmap</parameter> must belong to the same
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platform as <parameter>display</parameter>, and EGL considers
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the returned <type>EGLSurface</type> as belonging to that same
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platform. The EGL extension that defines the platform to which
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<parameter>display</parameter> belongs also defines the
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requirements for the <parameter>native_pixmap</parameter>
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parameter.
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</para>
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<para>
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Surface attributes are specified as a list of
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attribute-value pairs, terminated with
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<constant>EGL_NONE</constant>. Accepted attributes
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are:
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>EGL_GL_COLORSPACE</constant></term>
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<listitem>
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<para>
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Specifies the color space used by OpenGL and OpenGL ES
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when rendering to the surface. If its value is
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<constant>EGL_GL_COLORSPACE_SRGB</constant>, then a
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non-linear, perceptually uniform color space is assumed,
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with a corresponding
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<constant>GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING</constant>
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value of <constant>GL_SRGB</constant>. If its value is
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<constant>EGL_GL_COLORSPACE_LINEAR</constant>, then a
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linear color space is assumed, with a corresponding
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<constant>GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING</constant>
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value of <constant>GL_LINEAR</constant>. The default
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value of <constant>EGL_GL_COLORSPACE</constant> is
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<constant>EGL_GL_COLORSPACE_SRGB</constant>.
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</para>
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<para>
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Note that the <constant>EGL_GL_COLORSPACE</constant>
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attribute is used only by OpenGL and OpenGL ES contexts
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supporting sRGB framebuffers. EGL itself does not
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distinguish multiple colorspace models. Refer to the
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``sRGB Conversion'' sections of the OpenGL 4.6 and
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OpenGL ES 3.2 Specifications for more information.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_VG_ALPHA_FORMAT</constant></term>
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<listitem>
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<para>
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Specifies how alpha values are interpreted by OpenVG
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when rendering to the surface. If its value is
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<constant>EGL_VG_ALPHA_FORMAT_NONPRE</constant>,
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then alpha values are not premultipled. If its value
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is <constant>EGL_VG_ALPHA_FORMAT_PRE</constant>,
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then alpha values are premultiplied. The default
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value of <constant>EGL_VG_ALPHA_FORMAT</constant> is
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<constant>EGL_VG_ALPHA_FORMAT_NONPRE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EGL_VG_COLORSPACE</constant></term>
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<listitem>
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<para>
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Specifies the color space used by OpenVG when
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rendering to the surface. If its value is
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<constant>EGL_VG_COLORSPACE_sRGB</constant>, then a
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non-linear, perceptually uniform color space is
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assumed, with a corresponding
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<type>VGImageFormat</type> of form
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<constant>VG_s*</constant>. If its value is
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<constant>EGL_VG_COLORSPACE_LINEAR</constant>, then
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a linear color space is assumed, with a
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corresponding <type>VGImageFormat</type> of form
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<constant>VG_l*</constant>. The default value of
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<constant>EGL_VG_COLORSPACE</constant> is
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<constant>EGL_VG_COLORSPACE_sRGB</constant>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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Any EGL rendering context that was created with respect to
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<parameter>config</parameter> can be used to render into the
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surface. Use
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<citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry>
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to attach an EGL rendering context to the surface.
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</para>
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<para>
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Use
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<citerefentry><refentrytitle>eglQuerySurface</refentrytitle></citerefentry>
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to retrieve the ID of <parameter>config</parameter>.
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</para>
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<para>
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Use <citerefentry><refentrytitle>eglDestroySurface</refentrytitle></citerefentry>
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to destroy the surface.
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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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The <constant>EGL_MATCH_NATIVE_PIXMAP</constant> attribute
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of
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<citerefentry><refentrytitle>eglChooseConfig</refentrytitle></citerefentry>
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can be used to select a frame buffer configuration matching
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a specified native pixmap.
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</para>
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<para>
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Attribute <constant>EGL_GL_COLORSPACE</constant> is supported
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only if the EGL version is 1.5 or greater.
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</para>
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<para>
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Attributes
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<constant>EGL_VG_ALPHA_FORMAT</constant> and
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<constant>EGL_VG_COLORSPACE</constant>, and the
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corresponding attribute values, are supported only if the
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EGL version is 1.2 or greater.
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</para>
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<!-- Might want to mention aliasing of EGL_VG_* -> EGL_* that occurred in EGL 1.3 -->
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<para>
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The <constant>EGL_VG_ALPHA_FORMAT</constant> and
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<constant>EGL_VG_COLORSPACE</constant> attributes are used only
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by OpenVG and EGL itself. Refer to section 11.2 of the OpenVG
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1.0 specification for more information. The platform's use and
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interpretation of alpha values is outside the scope of EGL.
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However, the preferred behavior is for the window system to
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ignore the value of <constant>EGL_VG_ALPHA_FORMAT</constant>.
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</para>
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</refsect1>
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<refsect1 xml:id="errors"><title>Errors</title>
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<para>
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If <parameter>display</parameter> and
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<parameter>native_pixmap</parameter> do not belong to the same
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platform, then undefined behavior occurs.
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</para>
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<para>
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<constant>EGL_NO_SURFACE</constant> is returned if creation of
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the surface fails.
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</para>
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<para>
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<constant>EGL_BAD_DISPLAY</constant> is generated if
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<parameter>display</parameter> is not an EGL display connection.
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</para>
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<para>
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<constant>EGL_NOT_INITIALIZED</constant> is generated if
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<parameter>display</parameter> has not been initialized.
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</para>
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<para>
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<constant>EGL_BAD_CONFIG</constant> is generated if
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<parameter>config</parameter> is not an EGL config.
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</para>
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<para>
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<constant>EGL_BAD_NATIVE_PIXMAP</constant> may be generated if
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<parameter>native_pixmap</parameter> is not a valid native pixmap.
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</para>
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<para>
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<constant>EGL_BAD_ATTRIBUTE</constant> is generated if
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<parameter>attrib_list</parameter> contains an invalid pixmap attribute
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or if an attribute value is not recognized or out of range.
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</para>
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<para>
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<constant>EGL_BAD_ALLOC</constant> is generated if there is
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already an <type>EGLSurface</type> associated with
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<parameter>native_pixmap</parameter> (as a result of a previous
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<function>eglCreatePlatformPixmapSurface</function> call).
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</para>
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<para>
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<constant>EGL_BAD_ALLOC</constant> is generated if the
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implementation cannot allocate resources for the new EGL window.
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</para>
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<para>
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<constant>EGL_BAD_MATCH</constant> is generated if the attributes of
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<parameter>native_pixmap</parameter> do not correspond to
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<parameter>config</parameter> or if
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<parameter>config</parameter> does not support rendering to pixmaps
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(the <constant>EGL_SURFACE_TYPE</constant> attribute does not contain
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<constant>EGL_PIXMAP_BIT</constant>).
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</para>
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<para>
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<constant>EGL_BAD_MATCH</constant> is generated if
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<parameter>config</parameter> does not support the specified
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OpenVG alpha format attribute (the value of
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<constant>EGL_VG_ALPHA_FORMAT</constant> is
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<constant>EGL_VG_ALPHA_FORMAT_PRE</constant> and the
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<constant>EGL_VG_ALPHA_FORMAT_PRE_BIT</constant> is not set
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in the <constant>EGL_SURFACE_TYPE</constant> attribute of
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<parameter>config</parameter>) or colorspace attribute (the
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value of <constant>EGL_VG_COLORSPACE</constant> is
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<constant>EGL_VG_COLORSPACE_LINEAR</constant> and the
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<constant>EGL_VG_COLORSPACE_LINEAR_IT</constant> is not set
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in the <constant>EGL_SURFACE_TYPE</constant> attribute of
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<parameter>config</parameter>).
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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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<citerefentry><refentrytitle>eglDestroySurface</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>eglChooseConfig</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>eglGetConfigs</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>eglMakeCurrent</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>eglQuerySurface</refentrytitle></citerefentry>
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</para>
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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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