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<refentry xml:base="" id="eglSwapBuffers">
<holder>The Khronos Group Inc.</holder>
post <acronym>EGL</acronym> surface color buffer to a native window
<title>C Specification</title>
<funcdef>EGLBoolean <function>eglSwapBuffers</function></funcdef>
<paramdef>EGLDisplay <parameter>display</parameter></paramdef>
<paramdef>EGLSurface <parameter>surface</parameter></paramdef>
<refsect1 id="parameters"><title>Parameters</title>
Specifies the EGL display connection.
Specifies the EGL drawing surface whose buffers are to be swapped.
<refsect1 id="description"><title>Description</title>
If <parameter>surface</parameter> is a window surface,
<function>eglSwapBuffers</function> posts its color buffer
to the associated native window.
The contents of ancillary buffers are always undefined after
calling <function>eglSwapBuffers</function>. The contents of
the color buffer are left unchanged if the value of the
<constant>EGL_SWAP_BEHAVIOR</constant> attribute of
<parameter>surface</parameter> is
<constant>EGL_BUFFER_PRESERVED</constant>, and are undefined
if the value is <constant>EGL_BUFFER_DESTROYED</constant>.
The value of <constant>EGL_SWAP_BEHAVIOR</constant> can be
set for some surfaces using
<function>eglSwapBuffers</function> performs an implicit
flush operation on the context (<function>glFlush</function>
for an OpenGL ES or OpenGL context,
<function>vgFlush</function> for an OpenVG context) bound to
<parameter>surface</parameter> before swapping. Subsequent
client API commands may be issued on that context
immediately after calling
<function>eglSwapBuffers</function>, but are not executed
until the buffer exchange is completed.
If <parameter>surface</parameter> is a pixel buffer or a pixmap,
has no effect, and no error is generated.
<refsect1 id="notes"><title>Notes</title>
Attribute <constant>EGL_SWAP_BEHAVIOR</constant> is
supported only if the EGL version is 1.2 or greater. In
earlier versions, behavior is as though the attribute
exists, and always has the value
The EGL 1.4 specification was updated to acknowledge that
ancillary buffers are not necessarily preserved after a
swap, and that the <constant>EGL_SWAP_BEHAVIOR</constant>
attribute applies only to the color buffer. This change in
the specification acknowledged the behavior of many shipping
implementations, and is not intended to result in behavior
changes in any existing implementation. Applications which
require preservation of ancillary buffers across a swap
should be aware that not all implementations can preserve
them, and that EGL 1.4 has no way to query whether or not
they are preserved.
<refsect1 id="errors"><title>Errors</title>
<constant>EGL_FALSE</constant> is returned if swapping of the
surface buffers fails, <constant>EGL_TRUE</constant> otherwise.
<constant>EGL_BAD_DISPLAY</constant> is generated if
<parameter>display</parameter> is not an EGL display connection.
<constant>EGL_NOT_INITIALIZED</constant> is generated if
<parameter>display</parameter> has not been initialized.
<constant>EGL_BAD_SURFACE</constant> is generated if
<parameter>surface</parameter> is not an EGL drawing surface.
<constant>EGL_CONTEXT_LOST</constant> is generated if a power management
event has occurred. The application must destroy all contexts and
reinitialise OpenGL ES state and objects to continue rendering.
<refsect1 id="seealso"><title>See Also</title>
<refsect3 id="Copyright"><title></title>
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