The case for a "SceneGraph"

[Alan Griffiths]

On 19/07/13 10:55, Michał Sawicz wrote:
> I'm sure it was discussed before, but can you guys please give me a
> summary why it's not possible to just keep the shell's scenegraph (in
> our case the Qt/QML one) in play? Or if there maybe is another way for
> shell's scenegraph to another process's surface for "internal" composition?

Mir components have a dependency on the scenegraph to provide them with
information. This dependency exists in several contexts - e.g. system
compositing and session compositing. There needs to be a better
abstraction of these needs within Mir than exists at present because we
are beginning to encounter issues like
https://code.launchpad.net/~robertcarr/mir/session-transactions/+merge/175669.

As to the suitability of the Qt scenegraph: the compositor, in
particular, needs fast response to its queries - so I'm doubtful about
implementing them across language boundaries. (I also suspect that it
would be hard to satisfy all the functional requirements in Mir this way.)