[Merge] lp:~gerboland/qtubuntu/adopt-more-eglconvenience2 into lp:qtubuntu

[Gerry Boland]

The proposal to merge lp:~gerboland/qtubuntu/adopt-more-eglconvenience2 into lp:qtubuntu has been updated.

Commit Message changed to:

Convert UbuntuOpenGLContext to use QEGLPlatformContext, and allow clients to customize chosen GLConfig

Several things come of this change
1. Convert UbuntuOpenGLContext to use QEGLPlatformContext means we can use more built-in Qt code to configure and use the GL context, which should ensure that Qt-on-Mir applications behave more consistently with Qt-on-X apps.
2. Allow apps to configure the SurfaceFormat/GLConfig, as opposed to always overruling it to be ABGR8888. But choose ABGR8888 as the default if not specified by the app.
3. If app does not request alpha channel, but still gets a GLConfig with an alpha channel, communicate to Mir that the alpha channel is unused (aka XBGR8888), and thus compostor need not blend the surface.

For more details, see:
https://code.launchpad.net/~gerboland/qtubuntu/adopt-more-eglconvenience2/+merge/295248
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Your team Ubuntu Phablet Team is requested to review the proposed merge of lp:~gerboland/qtubuntu/adopt-more-eglconvenience2 into lp:qtubuntu.