KHR_vg_parent_image

EGL_KHR_vg_parent_image

Ignacio Llamas
Gary King
Chris Wynn

Gary King, NVIDIA Corporation (gking 'at' nvidia.com)

Copyright (c) 2006-2013 The Khronos Group Inc. Copyright terms at
    http://www.khronos.org/registry/speccopyright.html

Complete.
Approved by the Khronos Board of Promoters on February 11, 2008.

Version 5, October 8, 2008

EGL Extension #4

This extension requires EGL 1.2 and the EGL_KHR_image extension,
and an OpenVG implementation

This specification is written against the wording of the EGL Image
(EGL_KHR_image) specification.

This extension provides a mechanism for creating EGLImage objects
from OpenVG VGImage API resources.  For an overview of EGLImage
operation, please see the EGL_KHR_image specification.

None

None

      EGL_VG_PARENT_IMAGE_KHR                       0x30BA

Add the following to Table aaa (Legal values for CreateImageKHR
<target> parameter), Section 2.5.1 (EGLImage Specification)

  +--------------------------+--------------------------------------------+
  |  <target>                |  Notes                                     |
  +--------------------------+--------------------------------------------+
  |  EGL_VG_PARENT_IMAGE_KHR     |  Used for OpenVG VGImage objects           |
  +--------------------------+--------------------------------------------+

Insert the following text after paragraph 3 ("If <target> is
NATIVE_PIXMAP_KHR...") of Section 2.5.1 (EGLImage Specification):

"If <target> is EGL_VG_PARENT_IMAGE_KHR, <dpy> must be a valid EGLDisplay,
<ctx> must be a valid OpenVG API context on that display, and <buffer>
must be a handle of a VGImage object valid in the specified context, cast
into the type EGLClientBuffer.  Furthermore, the specified VGImage
<buffer> must not be a child image (i.e. the value returned by
vgGetParent(<buffer>) must be <buffer>).  If the specified VGImage
<buffer> has any child images (i.e., vgChildImage has been previously
called with the parent parameter set to <buffer>), all child images will
be treated as EGLImage siblings after CreateImageKHR returns.  Any values
specified in <attr_list> are ignored."

Add the following errors to the end of the list in Section 2.5.1 (EGLImage
Specification):

"   * If <target> is EGL_VG_PARENT_IMAGE_KHR, and <dpy> is not a
      valid EGLDisplay, the error EGL_BAD_DISPLAY is generated.

    * If <target> is EGL_VG_PARENT_IMAGE_KHR and <ctx> is not a
      valid EGLContext, the error EGL_BAD_CONTEXT is generated.

    * If <target> is EGL_VG_PARENT_IMAGE_KHR and <ctx> is not a valid
      OpenVG context, the error EGL_BAD_MATCH is returned.

    * If <target> is EGL_VG_PARENT_IMAGE_KHR and <buffer> is not a handle
      to a VGImage object in the specified API context <ctx>, the error
      EGL_BAD_PARAMETER is generated.

    * If <target> is EGL_VG_PARENT_IMAGE_KHR, and the VGImage specified by
      <buffer> is a child image (i.e., vgGetParent(<buffer>) returns
      a different handle), the error EGL_BAD_ACCESS is generated."

1.  Should this specification allow the creation of EGLImages
    from OpenVG child images?

    RESOLVED:  No.  It is believed that properly addressing the
    interaction of hardware restrictions (e.g., memory alignment),
    arbitrary image subrectangles, scissor rectangles and viewport
    rectangles may create an undue burden on implementers.  In the
    interest of providing a useful spec in a timely fashion, this
    functionality has been disallowed, with the possibility of
    providing it (if necessary) through a future layered extension.

    This restriction is shared with eglCreatePbufferFromClientBuffer;
    however, this specification allows EGL Images to be created
    from VGImages which have child images, functionality not
    previously available.