angle/extensions/EGL_ANGLE_x11_visual.txt

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Name
ANGLE_x11_visual
Name Strings
EGL_ANGLE_x11_visual
Contributors
Corentin Wallez, Google
Shannon Woods, Google
Jamie Madill, Google
Geoff Lang, Google
Contacts
Corentin Wallez, Google (cwallez 'at' chromium 'dot' org)
Status
Draft
Version
Version 1, 2015-11-13
Number
EGL Extension XXX
Extension Type
EGL client extension
Dependencies
Requires EGL_EXT_client_extensions to query its existence without
a display.
Requires EGL_EXT_platform_base.
This extension is written against the wording of version 9 of the
EGL_EXT_platform_base specification.
Written based on the wording of the EGL 1.5 Specification
(August 7 2014).
Overview
This extension allows passing the X11 visual ID used by the native
EGL surface types at display creation time. This will restrict
EGLSurfaces to be created from native types with this visual ID,
which may allow the created display to be more compatible and
performant.
New Types
None
New Procedures and Functions
None
New Tokens
Accepted as an attribute name in the <attrib_list> argument of
eglGetPlatformDisplayEXT:
EGL_X11_VISUAL_ID_ANGLE 0x33A3
Additions to the EGL Specification
Modify section 3.5.1 (Creating On-Screen Rendering Surfaces), p. 34
Append the following to the errors of CreateWindowSurface:
"If an X11 visual was specified at display creation time using
EGL_ANGLE_X11_VISUAL_ID that is not equal to the ID of the
native_window's visual, an EGL_BAD_MATCH error is generated and
EGL_NO_SURFACE is returned."
New Behavior
To request a display created with a X11 visual ID, the value of
EGL_ANGLE_X11_VISUAL_ID should be set to a valid X11 visual ID. If
present, this ID will be used during display creation to make a
display that is more compatible and potentially more performant when
used with EGLsurfaces created from native types with this ID. If the
visual ID passed isn't a valid visual ID, eglGetPlatformDisplay will
return EGL_NO_DISPLAY and generate an EGL_NOT_INITIALIZED error.
Issues
1) When the hint is present, should EGLsurface creation functions
only accept native types with the hint's visual ID?
RESOLVED: Yes, generate an error when the visual of the native
surface doesn't match. This will avoid having hidden performance
or compatibility losses when using this extension.
Revision History
Version 1, 2015-11-13 (Corentin Wallez)
- Initial draft