DemoRenderer: GL_BLEND is really always enabled even when not required (also causes RGBX discolouration in mir_proving_server)

Trevinho reports RGBX surfaces are getting blended incorrectly. I think that would be this bug.

On the other hand, that could also be related to: bug 1424909

Yeah, basically using sdl1.2, a both using an A*_8888 format and an X*_8888 format surface is blended anyway (here's what I mean http://i.imgur.com/VgM6Uyu.png).

By writing the alpha channel to 0xff by hand (with something like http://pastebin.ubuntu.com/10394442/), problem is fixed.

I'm not sure OpenGL has any support for uploading RGBX/XRGB pixel data (extensions?). It only seems to support RGBA/ARGB etc. So for that reason we might have to drop support (or warn and deprecate) for software surfaces with 32-bit RGBX/XRGB.

We do indeed need to populate the alpha channel by hand. And I suggest that's better done in the client than a hack in Mir. So you should probably switch to RGBA/ARGB etc now.

Ordinarily there should be zero overhead to setting the alpha channel to 0xff because you're usually writing your pixels in at least 32-bit chunks (or should be).

So I suggest looking at your source pixel data. Switch that to RGBA and you can remove the CPU-intensive hack.

This is still a problem, now for Xmir. Xmir prefers RGBX_8888 type pixel formats, however when on screen the colours are weird with odd transparency. That's probably because mir_proving_server is using the X byte as alpha A, but X is uninitialized.

Fix committed into lp:mir at revision None, scheduled for release in mir, milestone 0.18.0

This bug was fixed in the package mir - 0.18.0+16.04.20151216.1-0ubuntu1

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mir (0.18.0+16.04.20151216.1-0ubuntu1) xenial; urgency=medium

  [ Kevin DuBois ]
  * New upstream release 0.18.0 (https://launchpad.net/mir/+milestone/0.18.0)
    - ABI summary: Only servers need rebuilding;
      . Mirclient ABI unchanged at 9
      . Mirserver ABI bumped to 36
      . Mircommon ABI unchanged at 5
      . Mirplatform ABI unchanged at 11
      . Mirprotobuf ABI unchanged at 3
      . Mirplatformgraphics ABI bumped to 7
      . Mirclientplatform ABI unchanged at 3
      . Mirinputplatform ABI added. Current version is 4
    - Enhancements:
      . Use libinput by default, and remove the android input stack
      . Add x11 input probing
      . Add alternative buffer swapping mechanism internally, available with
        --nbuffers 0
      . Automatic searching and selection of input platforms
      . Better support for themed cursors
      . Add demo client that uses multiple buffer streams in one surface
      . Improve fingerpaint demo to use touch pressure
      . Allow for configuring cursor acceleration, scroll speed and left or
        right handed mice
      . Allow for setting a base display configuration via client api
      . Various nested server multimonitor fixes and stability improvements
      . Remove DepthId from the SurfaceStack
    - Bug fixes:
      . Unit test failures in Display.* on Android (LP: #1519276)
      . Build failure due to missing dependency of client rpc code on mir
        protobuf (LP: #1518372)
      . Test failure in
        NestedServer.display_configuration_reset_when_application_exits
        (LP: #1517990)
      . CI test failures in various NesterServer tests (LP: #1517781)
      . FTBFS with -DMIR_PLATFORM=android (LP: #1517532)
      . Nesting Mir servers with assorted display configs causes lockup
        (LP: #1516670)
      . [testsfail] RaiseSurfaces.motion_events_dont_prevent_raise
        (LP: #1515931)
      . CI test failures in GLMark2Test (LP: #1515660)
      . Shells that inject user input events need to agree with the system
        compositor on the clock to use (LP: #1515515)
      . mircookie-dev is missing nettle-dev dependency (LP: #1514391)
      . Segmentation fault on server shutdown with mesa-kms (LP: #1513901)
      . mircookie requires nettle but libmircookie-dev doesn't depend on it
        (LP: #1513792)
      . libmircookie1 package does not list libnettle as dependency
        (LP: #1513225)
      . display configuration not reset when application exits (LP: #1511798)
      . unplugging external monitor causes nested server to throttle client
        (LP: #1511723)
      . 1/2 screen on external monitor (LP: #1511538)
      . unity-system-compositor crash, no interaction on windowed mode
        (LP: #1511095)
      . [regression] arm64/powerpc cross compile doesn't build any more
        (LP: #1510778)
      . mir_connection_get_egl_pixel_format() crashes if libEGL is loaded
        RTLD_LAZY (LP: #1510218)
      . [multimonitor] nested server surface positioning incorrect
        (LP: #1506846)
      . unity-system-compositor fails to build against lp:mir r3027
   ...