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Document the roles of MetaSurfaceActor and MetaWindowActor, and when their subclasses are used. (And this is actually the first real documentation under src/compositor/README!) https://gitlab.gnome.org/GNOME/mutter/merge_requests/368
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70 lines
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2.5 KiB
Text
Intro
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=====
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In general, the compositor splits the window from the contents of
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the window from the shape of the window. In other words, a window
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has contents, and the contents of the window have a shape. This is
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represented by the actor hierarchy:
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+--------------------------------------+
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| MetaWindowActor |
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| +----------------------------------+ |
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| | MetaSurfaceActor | |
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| | +------------------------------+ | |
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| | | MetaShapedTexture | | |
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| | +------------------------------+ | |
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| +----------------------------------+ |
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+--------------------------------------+
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Surfaces may also contain subsurfaces. The MetaWindowActor and
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MetaSurfaceActor subclasses that will be created depend on the client
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type, and the display server type.
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## Subsurfaces
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Additionally, there is also the case of subsurfaces: surfaces that
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are child of other surfaces. That is also represented in the actor
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hierarchy by having one or many MetaSurfaceActors (the subsurfaces)
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added as children of a parent MetaSurfaceActor. There are no limits
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to how many subsurfaces a surface may have. With subsurfaces, the
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actor hierarchy looks like this:
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MetaWindowActor
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↳ MetaSurfaceActor (surface)
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↳ MetaShapedTexture
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↳ MetaSurfaceActor (subsurface)
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↳ MetaShapedTexture
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↳ MetaSurfaceActor (sub-subsurface)
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↳ MetaShapedTexture
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↳ MetaSurfaceActor (subsurface)
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↳ MetaShapedTexture
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In this example, the main surface has 2 subsurfaces. One of these
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subsurfaces contains a subsurface as well.
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All MetaWindowActors contain at least one MetaSurfaceActor, and all
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MetaSurfaceActors contain a MetaShapedTexture.
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## Client and compositor
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MetaWindowActor and its subclasses represent the client window's
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type. A X11 client will have a MetaWindowActorX11 representing it,
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and a Wayland client will have a MetaWindowActorWayland.
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On the compositor side, the surface where the contents of the window
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are drawn into are represented by MetaSurfaceActor subclasses. On a
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Wayland session, windows are backed by a MetaSurfaceActorWayland
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surface, whereas on X11 sessions, by MetaSurfaceActorX11.
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XWayland windows are X11 client windows (MetaWindowActorX11) backed
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by Wayland surfaces (MetaWindowActorWayland).
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Env Vars
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========
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MUTTER_DISABLE_MIPMAPS - set to disable use of mipmaped windows. |