[Mesa-dev] [Bug 67676] Transparent windows no longer work

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=67676

Chad Versace <chad.versace at intel.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|mesa-dev at lists.freedesktop. |jonny.lamb at collabora.co.uk
                   |org                         |

--- Comment #14 from Chad Versace <chad.versace at intel.com> ---
n reply to Jonny Lamb from comment #13)
> Created attachment 113563 [details]
> version three

Comments:

- Good call on specifying pre-multiplied alpha.

- I think you should remove the paragraph

    To determine if the EGL implementation supports this extension, clients
    should query the EGL_EXTENSIONS string of the current active display.

  because that's the normal way of querying extensions and needs no
  explanation. I found that paragraph confusing because it made me ask "Why is
  the extension telling me this? Is there some magic in this extension that
I've
  failed to see that warrants this explanation?". The platform extension
  specification that you used as a template explicitly describes how to perform
  the extension query because its query mechanism differs from 95% of existing
  EGL extensions.

- You should remove the "New Behavior" section. Normally, the fine details of
  an extension specification are defined in the "Additions to the EGL x.y
  specification" section as a diff against the EGL x.y spec. This extension is
no
  different. A few, special extensions, though, define behavior that should
*not*
  be added to the EGL spec, such as the platform extensions. That's what the
"New
  Behavior" section should be used for, and this alpha extension defines no
such
  "outside-of-the-spec" behavior.

- The paragraph

    To obtain an EGL window surface with a meaningful alpha channel, use an
    EGLConfig with EGL_TRANSPARENT_TYPE set to EGL_TRANSPARENT_ALPHA_MESA.

  is still valuable, despite belonging in the "New Behavior" section. The
  proper location for it is the "Overview" section.

- Regarding issue #1:

    RESOLUTION: Yes. Non-window surfaces created with
    EGL_TRANSPARENT_TYPE set to EGL_TRANSPARENT_ALPHA_MESA will
    generate an error.

  What error does it generate? If we refer to this paragraph of Section 3.5.1
as precedent,

    If config does not support rendering to windows (the EGL_SURFACE_TYPE
    attribute does not contain EGL_WINDOW_BIT ), an EGL_BAD_MATCH error is
    generated.

  then the resolution text can be clarified as:

    RESOLUTION: Attempting to create a non-window surface with a config in
    which EGL_TRANSPARENT_TYPE is EGL_TRANSPARENT_ALPHA_MESA, then an
    EGL_BAD_MATCH error is generated.


- Other than the above (mostly sylistic) issues, the extension looks good to
  me.  Thanks for writing it! When you submit to mesa-dev, please CC me.

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