eglSwapBuffers

Name

eglSwapBuffers — post EGL surface color buffer to a native window

C Specification

`EGLBoolean eglSwapBuffers(`	EGLDisplay `display`,
	EGLSurface `surface)`;

Parameters

display: Specifies the EGL display connection.
surface: Specifies the EGL drawing surface whose buffers are to be swapped.

Description

If surface is a window surface, eglSwapBuffers posts its color buffer to the associated native window.

The contents of ancillary buffers are always undefined after calling eglSwapBuffers. The contents of the color buffer are left unchanged if the value of the EGL_SWAP_BEHAVIOR attribute of surface is EGL_BUFFER_PRESERVED, and are undefined if the value is EGL_BUFFER_DESTROYED. The value of EGL_SWAP_BEHAVIOR can be set for some surfaces using eglSurfaceAttrib.

eglSwapBuffers performs an implicit flush operation on the context (glFlush for an OpenGL ES or OpenGL context, vgFlush for an OpenVG context) bound to surface before swapping. Subsequent client API commands may be issued on that context immediately after calling eglSwapBuffers, but are not executed until the buffer exchange is completed.

If surface is a pixel buffer or a pixmap, eglSwapBuffers has no effect, and no error is generated.

Notes

Attribute EGL_SWAP_BEHAVIOR 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 EGL_BUFFER_DESTROYED.

The EGL 1.4 specification was updated to acknowledge that ancillary buffers are not necessarily preserved after a swap, and that the EGL_SWAP_BEHAVIOR 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.

Errors

EGL_FALSE is returned if swapping of the surface buffers fails, EGL_TRUE otherwise.

EGL_BAD_DISPLAY is generated if display is not an EGL display connection.

EGL_NOT_INITIALIZED is generated if display has not been initialized.

EGL_BAD_SURFACE is generated if surface is not an EGL drawing surface.

EGL_CONTEXT_LOST 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.