Struct runa_orbiter::shell::surface::roles::Subsurface

pub struct Subsurface<S: Shell> { /* private fields */ }

The wl_subsurface role.

Note about cache and pending states

A surface normally has a pending and a current state. Changes are applied to the pending state first, then commited to the current state when wl_surface.commit is called.

Subsurfaces has one more state - the cached state. This state exists if the subsurface is in synchronized mode. In sync mode, commit applies pending state to a cached state, and the cached state is applied to current state when the parent calls commit, if the partent is desynced; otherwise the cached state becomes part of the parent’s cached state.

We can see this as a tree of surface states, rooted at a “top-level” surface, such as a surface with the xdg_toplevel role. The root’s current state references the children’s current states, and the children’s current states in turn reference the grand-children’s, so on and so forth. When a synced child commits, its current state updates, but it doesn’t update its parent’s reference to its current state. So the parent still references the previous state, until the parent also commits.

A complication is when a child is destroyed, either by destroying the surface or deactivating its role, it’s immediately removed, without going through the pending or the cached state. We can detect this by checking if the role object is active, while going through the tree of surfaces.

Implementations

impl<S: Shell> Subsurface<S>

pub fn attach( parent: Rc<Surface<S>>, surface: Rc<Surface<S>>, shell: &mut S ) -> bool

Attach a surface to a parent surface, and add the subsurface role to id.

pub fn parent(&self) -> &Weak<Surface<S>>

Returns a weak reference to the parent surface.

Trait Implementations

impl<S: Shell> Clone for Subsurface<S>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<S> Debug for Subsurface<S>where S: Debug + Shell,

fn fmt(&self, __f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<S: Shell> Role<S> for Subsurface<S>

fn name(&self) -> &'static str

The name of the interface of this role.

fn is_active(&self) -> bool

Returns true if the role is active.

fn deactivate(&mut self, shell: &mut S)

Deactivate the role.

fn provide<'a>(&'a self, demand: &mut Demand<'a>)

Provides type based access to member variables of this role.

fn provide_mut<'a>(&'a mut self, demand: &mut Demand<'a>)

Provides type based access to member variables of this role.

fn post_commit(&mut self, shell: &mut S, surface: &Surface<S>)

Called after the pending state becomes the current state, in Surface::commit

fn pre_commit( &mut self, _shell: &mut S, _surfacee: &Surface<S> ) -> Result<(), &'static str>

Called before the pending state becomes the current state, in Surface::commit. If an error is returned, the commit will be stopped.